the dslr field guide: the essential guide to getting the most from your camera

THEDSLRFIELDGUIDE

MichaelFreeman

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INTRODUCTION

Intheirinfancy,digitalSLRswerethepreserveofaselectgroupofprofessionalphotographers, or exceptionally wealthy enthusiasts. While 35mm SLRs hadreachedapoint in theirdevelopmentwhere therewassomethingforeveryone,regardless of their skill level or budget, the transition to sensor-based digitalcapturecamewithaprice-tagthatmadeitprohibitivelyexpensiveforthephotoenthusiast. To enjoy the benefits of photographywith an interchangeable lensdigital camerameant investing heavily in a technology thatwas evolving at aphenomenalrate,withmanufacturersturningoutsignificantlysuperiorcamerasonanalarminglyregularandbrieftimescale;adoublingofcameraresolutioninaslittleas12monthswascommon.

Today, however, the frenetic pace of DSLR development and the leaps in

technological“breakthroughs”haveslowed,althoughthatisn’ttosaytheyhaveceasedaltogether.Sensorresolutionscontinuetocreepupward,albeitinsmallerincrements,andnewtechnologiescontinuetobesqueezedintothecamerabodytoenhancethephotographer’sexperience;built-inanti-shakesystemstocombat

camera shake, in-camera dust-removal, liveLCD screens, andvideo recordingareallincreasinglycommon,forexample.ButitisnotthematuringtechnologythathasexpandedtheDSLRmarkettothepointthat35mmSLRsarenownear-obsolete,itisafarmorematerialaspect:price.Whileheftypricesexcludedmostnon-professionalphotographers(andmanypros) from“goingdigital”adecadeago,thelow-costofmodernDSLRsisnolongerabarrier.

YetwhilebuyingaDSLRno longer requires the same financial sacrifice, it

still demands an investment in time if you want to make the most of it.Fundamental photographic concepts such as aperture, shutter speed, and ISOmay not have changed since the day photographywas born as amedium, buttheirimplementationinthedigitalage,toacertainextent,has.Inaddition,thereareallof thenecessarydigital technologies thatneed tobemasteredor,at thevery least, understood.While some photographersmay be happy setting theircamerato“automatic”andallowingittodeterminethemanyandvariedpicture-takingparameters,touseaDSLRtoitsfullestpotentialthereisagreatdealtolearn.Thatispreciselywhyyouhaveboughtthisbook.WhatIaimtodohereistorevealhowyoucangettheverybestfromyourcamera,andshowhowdigitalcapturecan,andshould,changethewayyouthinkaboutshooting,regardlessofwhetherthisisyourfirstDSLRornot.

THE D IGITAL ENVIRONMENT PART I

There’s no doubt that if you’re already familiar with the basic controls of aconventionalfilmSLR—bywhichwemeantheaperture,shutterspeed,shootingmodes,andsoon—thentheswitchtoaDSLRshouldberelativelypainless. Ifyou’removingupfromadigitalpoint-and-shoot,youmayhavemoretolearnintermsoftechnique,butyou’llbefamiliarwithmuchofthe“vocabulary”thatisusedindigitalphotography.

The world of digital SLRs (DSLRs) is a rapidly evolving environment. It

seems almost inconceivable that it was only in 2000 that Canon launched itsflagshipDSLR, theD30,which featured a 3.1-megapixel sensor—a resolutionnowfoundonmanycameraphones.

However, thespeedof technologicalchangecanmakelifeexpensivefor the

photographyenthusiast,asimprovementstendtobemuchgreaterasnewcamera

modelsarelaunched.Onthefaceofit,thisissimplyamatterofbuyingadigitalbodytousewithexistinglensesandaccessories,andinonesenseitisnomorecomplicated than that. Nevertheless, exploiting the enormous capabilities ofdigital cameras and software to their fullest means immersing yourself in adifferentworld,and,after this initialchapter, starting toshoot intuitively.Thismeansnotfollowingthemanual—butitwillstillhelptohavereaditfirst.

DSLRs

TheDSLRoffersanexcellentcompromisebetweenimagequality,affordability,flexibility,andconvenience.Whiletherearemediumformatcamerasthatoffergreaterdynamicrange, lessnoise,and theultimate in imagequality, theirhighcostputsthemfirmlyintheprofessionalcategory.

AswithfilmSLRs,thebigdrawofDSLRsis thatyoucanseeexactlywhat

youareabout toshoot,fromframingtofocusanddepthoffield, thanksto theuseofaprismandflip-upmirrorthatdeliveranexactviewofthescenethatisabout tobecaptured.Youmayargue thatdigitalpoint-and-shootcameraswiththeir electronic, non-mechanical shutters also offer this, but it’s at the cost ofloadingmorecircuitryonto thesensor,withacorresponding reduction in theirimage-gatheringability.

SLRs also have interchangeable lenses, which vastly broadens their

capabilities.Indeed,allthemajorcameramanufacturershaveinvestedtheirbestefforts in image quality and operational perfection into SLR bodies—in otherwords,SLRsarewherethegoodstuffresides.

PentaxDSLR

DespiteenjoyingonlyarelativelysmallshareoftheDSLRmarket,Pentaxis

producinghigh-specificationcamerasthathavealoyalfollowing.

Ergonomically, 35mmSLRdesigns became highly refined over the past 70years, andwhile point-and-shoot cameras have produced a chaotic number ofstyles,DSLRshavefollowedtheirfilmpredecessors.But,althoughtheprinciplemaybe the sameas a filmcamera, the innerworkingsof adigital camera arequite different. For a start, the imaging is being performed by a silicon-basedchipsensor—eitheraCCD(charge-coupleddevice)orCMOS(complementarymetal-oxide semiconductor) containingmillions of light-sensitive photodiodes.Each photodiode converts light from the scene being photographed into avoltage that is proportional to the brightness. The charge is amplified, thentransferredtoanADC(analog-to-digitalconverter)thattranslatesthepatternofchargesrecordedbythesensorintodiscretebinarycode.ThiscodeissenttoaDSP (digital signal processor) that performs a varietyof operationsdependingontheneedsoftheimageandthesettingschosenbytheuser:reducingnoiseandadjustingbrightness,color,contrast,andsharpness, forexample.Finally,allofthedigitalinformationthatdefinestheimageissavedontothestoragemedium—amemorycardofonekindoranother.

Nikonvs.Canon

NikonandCanonremainthe“bigtwo”whenitcomestoDSLRcameras,

sharingaround80percentoftheoverallmarket.

sharingaround80percentoftheoverallmarket.

Thistechnologyhasimportantstructuralimplications.Therearenochambers

forafilmcassetteor take-up,andnomechanicallycomplexfilmtransport,butthespace that issavedisneededfor theprocessor,sensor,andtheirassociatedcircuitry, as well as the removable memory card. This all fits, just, and bycoincidence, the volume of a former 35mm SLR is approximately what isneeded for a digitalmodel.Manymechanical parts remain the same—mirror,lensconnection,pentaprism,andshuttermechanism.Thelast,incidentally,takesthe place of the all-electronic shutter found in some point-and-shoot models(whichenablesavideofeed);onlyrecentlyhavethemajorityofDSLRsalloweda real-time preview of the scene on the LCD screen, enablingDSLR users tocompose using the LCD screen as well as shoot video. The screen itself isalways a compromise on a handheld camera, and is necessarily inadequate insizefordetailedviewing.Digitalbackson“medium-format”camerascanhavemore sensible LCD screens, but on mainstream SLRs, the screen is for verybasic checking; judging color and image quality by appearance alone is

pointless.

Interestingly,onthesubjectofdigitalbacks,theolddivisionsbetweenformats

(35mm, rollfilm, and so on) are now becoming thoroughly blurred. The onlyreasonswhysomedifferencessurvivearehistorical.Mostbacksaredesignedtofit the standard range of rollfilm cameras (645 and 6x6cm in particular) andtheseofcoursehavetheirownstylesofdesignandergonomics.

Point-and-shoot

Althoughaffordable,entry-levelDSLRsaremaking in-roads, thevastmajorityofcamerasboughttodayarepoint-and-shoot.Themainfeaturethatdistinguisheshigh-endmodels,whichselltothe“prosumer”(high-endconsumer)sector,fromprofessionalSLRsisthattheyhaveafixedzoomlensinsteadofinterchangeablelenses.Sensorresolutionisnotnecessarilydifferent,andasmostdeliveratleasttheninemegapixelsnecessaryfornormalfull-pageprintreproduction,theyhavetheir uses for professional photography. Being light and small they can becarriedandusedunobtrusively,andsoareconvenienttohavearoundontheoff-chanceofapictureopportunity.Buildquality,however,isusuallynotashighasforSLRs,andtheirsmallersensorsmeanpoint-and-shootcamerascanstrugglewithpicturequality,particularlyinhighcontrastorlow-lightconditions.

OlympusPen

Despiteitspoint-and-shootstyledesign,theOlympusPeniscomparabletoaDSLRinjustabouteveryotherway;itfeaturesalargesensor,thelensesareinterchangeable,andimagequalityisonaparwithDSLRsofasimilarprice.

MicroFourThirds

A relatively new format that looks set to become popular with the prosumermarket is the new range of what are loosely described as “mirrorlessinterchangeablelenscameras”thatutilizetheMicroFourThirdssystem.

The Four Thirds system was developed by a collective of camera

manufacturers looking to produce a universal, cross-manufacturer range ofDSLRsdesignedspecificallyfordigitalphotography,asopposedtoDSLRsthatreliedon existing film-based technologies.As the systemwasdeveloped fromtheground-up,thecamerasandlensescouldbeoptimizedforoneanother,whilethesmallersensorsizeallowedcameramanufacturerstoproducesmallerDSLRcamerabodiesandlenses.

Micro Four Thirds is an extension of this, which dispenses with the reflex

mirror and prism of a traditional SLR, resulting in a very small body—oftenwithoutaviewfinder—whereimagecompositiontakesplaceusingtherearLCDscreen.Suchcamerassitbetweencompactsandfully-fledgeddigitalSLRs;theyarecomparable insize to largecompacts,butshareanSLR’sability tochangelenses,fromwide-angletotelephoto.

DSLRControls

TheDigitalSensor

ThesensorliesattheheartofallDSLRs.Itisanintegralpartofthecamerathatfeeds,or isservedby,almostallof thecamerafunctions.Asthetechnologyisstill evolving, gradual improvements in dynamic range capture and noisereductionareongoing,althoughincreasesinresolutionarenotasfrequentorasdramaticastheyoncewere.

This inevitablymeans new cameras, as there is no question at this point of

simplyupgradingasensor.Italsomeansthatifthesensorissometimesexposedtotheenvironment,asinanSLR,itneedsparticularcareandattentiontoavoidparticlesonthesurfaceanddamage.

Asensorisanarrayofphotoreceptorsembeddedonamicrochip,alongwith

the circuitry andcomponentsnecessary to record the lightvalues.Thecircuitsare etched into the wafer by repeating the photolithographic process of lightexposure andchemical treatment,with extremeprecision.Thewidthof circuitlinesistypicallylessthan4µm(4microns).Asanindicationofthecomplexity,Canon’s11.1-megapixelCMOSsensorhasapproximately700feet(200meters)of circuitry.The individual unit of a sensor is the photosite, aminusculewellthat is occupied principally, though not exclusively, by a photodiode. Thephotodiode converts the photons of light striking it into a charge—the morephotons,thehigherthecharge.Thechargeisthenreadout,convertedtoadigitalrecord, and processed.Each signal from each photosite becomes the light andcolorvalueforonepixel—whichisthebasicunitofadigitalimage.

Photodiodes record light rather than color, so this has to be added by

interpolation in the vast majority of sensor designs. The usual method is tooverlaythesensorarraywithatransparentcolormosaicofred,blue,andgreen.Asincolorfilmandcolormonitors,thesethreecolorsallowalmostallotherstobeconstructed.Thedifferencehere,however,isthatthecolorresolutionisone-third that of the luminance resolution. Oddly, perhaps, this doesn’t matter asmuchasthisfiguresuggests.Interpolationisusedtopredictthecolorforallthepixels,andperceptuallyitworkswell.Aswe’llseelaterinthisbookinthecolormanagement and optimization sections, color is a complex issue,psychologicallyaswellasphysically.Theultimateaiminphotographyisforthecolortolookright,andthisisheavilyjudgmental.

Sensordevelopment

All sensor manufacturers are seeking to improve the performance of theirparticular sensors—and attention is often focused on reducing the size ofphotosites or increasing the size of the sensors. There are special technicalchallenges for each, and resolution is not the only thing affected. A largerreceptor(suchas8 µm–8 microns,or0.008 mm)isslowertofillup,andthisisclaimedtogiveabetterdynamicrange,asisthecasefordeeperreceptors.

Capturingcolor

Photositesarenotabletodistinguishbetweendifferentwavelengthsoflight,andassuchareunable to recordvariations incolor;color isaddedby filtering thelight.TheentiresensoriscoveredwithaColorFilterArray(CFA)—amosaicofred,green,andbluefilters,oneforeachphotosite.Thecamera’sprocessortheninterpolatesthemissingtwo-thirdsofthecolorinformationfromthesurroundingpixels—at least theneighboringblockofeight.TheCFApattern,as illustratedhere, is not an even distribution of the three wavelengths. In order to bettercorrespondwithhumanvision,whichismostsensitivetogreen-yellow,thereareusuallytwiceasmanygreenfiltersasredandblue.

Photosites

Photositescreateanelectricalchargewhenstruckbylight.Anabsenceoflightmeans no electrical charge, resulting in black. On the other hand, if lightcontinues tostrikeaphotositebeyond its“holdingcapacity” the result ispure,featurelesswhite.Thisaccountsforthelinearresponseofdigitalsensorstolightrather than the subtle fall-off that allows film to capture a relatively widedynamicrange.

Sensortypes

Digitalcamerasutilizeoneoftwomaintypesofsensor—CCD(charge-coupleddevice, shown right) or CMOS (complementary metal oxide semiconductor).Chipsofallkindsaremade inwafer foundries,butasCCDsarea specializedvariety,theyaremorecostlytoproduce.CMOSfoundries,however,canbeusedto manufacture computer processors and memory, and so CMOS sensors cantake advantage of economies of scale. This makes them much cheaper thanCCDstoproduce,althoughsomeofthissavingisoffsetbytheneedtoovercomesome performance problems, notably noise, which means additional onboardprocessing.Inotherwords,CCDsareinherentlybetterforhigh-qualityimaging,

but once data processing has been factored in there is little to choose inperformance at the top end ofDSLRs. In factmost high-endDSLRsnowuseCMOSchips.

CMOSchipsareproducedaspartofasiliconwafer,likeothercomputerchips,andarecutintoindividualchipsusingadiamond-edgedsaw.Oncecutintoseparatepieces,thechipscanbeplacedontocircuitslikeanyothercomputer

chip.

Theproblemofmoiré

Theproblemofmoiré

Lightfromcertainsubjects,suchasfabricsormaterialswithatightweave,canoccasionally only activate certain rows of the sensor’s pixels, leavingneighboringrowsinactive,or“dark.”Thisresults inaneffectknownasmoiré,which usually manifests itself as wavy patterns, and is an interference effectcaused by the overlapping of tight, fine patterns. In digital photography, thisspecialkindofartifactingisparticularlycommonbecauseofthegridpatternofphotositesonthesensor.Ifasecondpatternwithasimilarspacingisshot,suchasatextileweave,itcaninteracttocreateamoirépattern,asshownhere.Thecamera’s low-pass filter helps to reduce the effect, although only to a certaindegree as strong correction softens the image overall. The lenses, sensor, andsoftware in aDSLR system are all designed for high sharpness and accuracy,andthismakesmoirémorelikely.

Toavoidorreducemoiré:

•Changethecameraangleorposition.

• Change the point of focus and/or aperture. (Moiré is afunctionofsharpfocusandhighdetail.)

•Varythelensfocallength.

Removewithimage-editingsoftware.

Warning:alwaysinspectformoiréat100%magnification.Atsmallermagnificationsyoucanoftenseeafalsemoiré,whichistheinteractionoftheimagewiththepixelsinacamera’sLCDscreenoracomputermonitor.

Picturesufferingfrommoiré

Combatingmoiré

To combat moiré, light is passed through a low-pass filter that effectivelyspreads light by the width of a pixel, both horizontally and vertically. Thisresults inmore accurate data separation. The filter illustrated here is Canon’sthree-layerfilter,inwhichaphaseplate—whichconvertslinearlypolarizedlightintocircularlypolarized light—issandwichedbetween two layers that separateimagedataintohorizontalandverticaldirections.Anothersubstratecutsinfraredwavelengths by a combination of reflection and absorption to further improvecoloraccuracy.

DataTransfer

Oncethesensorhascapturedthelightfromthesubjectandgeneratedacharge,

the data has to be transferred in a readable form to the camera’s processor asquicklyandasaccuratelyaspossible,andtherearedifferentwaysofachievingthis.

Theoriginalmethod,whichgavetheCCD(charge-coupleddevice)itsname,

reliesonreadingoutthechargesrowbyrow,linkingtheendofonerowtothebeginningofthenext.Inthisway,thechargesare“coupled.”

Improvingspeed

Oneofthekeyissuesisthespeedatwhichtheimagedatacanbemovedoffthesensorsothatitisreadyforthenextexposure.Thisdecidestheshootingspeed—animportantfactorforsportsandnewsphotographersinparticular—andthebaseline that most professionals have become used to is the eight‑frames persecondcommonamonghigh-endcameras.

At themoment, there are threemethodsusedby sensors—interline transfer,

fullframetransfer,orX-Yaddressing—ofwhichinterlinetransfer,readingonecolumn at a time, is the traditional method. All have advantages anddisadvantages, anddifferentmanufacturers favoroneor theother according tohowtheychoosetosolveinherentproblems.Thelessonhereforphotographersisthatthereisnosteadyprogressionofsensorimprovement,butamorechaoticworldofinnovationandsecretiveindependentengineering—problemsthatonceseemedintractablecansuddenlyhaveasolution.

Datareadout

Improving the speed and efficiency of data transfer is a critical area ofdevelopment.Currentlytherearethreemethodsoftransferringthedatafromanexposedsensor:

Interlinetransfer

Inthisbasic,originalmethod(whichgaveCCDstheirname)thedatafromthephotositesisshuntedtoonesideofthesensorsothattherowscanbereadoneata time, with the end of one linked to the start of the next. The readout istherefore sequential.Originally developed for video, its disadvantages for stilldigital capture are the time it takes to shunt the data across the array, and theneed for transfer channels adjacent to the photodiodes, which reduces theapertureratioatthephotosite.

X-Yaddressing

Eachphotositeisreadindividually,whichcutsdownthetransfertimeandofferspotential processing advantages. It requires individual switches for each site,which potentially reduces the area available for the photodiode, reducing theapertureratio.ThismethodisusedinCMOSsensorsandsomeothers(suchastheNikonLBCAST,whichusesburiedchannels).

Full-frametransfer

Allofthedataismovedatoncedownontoanareathesamesizeasthesensor.This adds another layer of the same area as the sensor, but as the transferchannelscanbeunderneaththephotosites,thephotodiodescanoccupyalargerarea.Italsoaddressestheissueoftransferspeed.

1Lightstrikestheactiveareaofthephotodiode.

2Thephotodiodeconvertsthequantityoflightintoan

accumulatedcharge.

3Thechargeismovedoffthesensor(withalltheothercharges

fromotherphotosites)throughtransferchannelstoanamplifier.

4TheamplifiedchargeismovedtotheADC(analog-to-digital

converter).

5ThesignalisprocessedbytheADCintodigitaldata.

6Theimagingengineprocessestheimageinanumberofways,

includingapplyingusersettings,compressing,andreducingnoise.

7Thedataistransferredtothememorycardordirecttothe

computer’sharddrive(ifthecameraisconnected).

THE D IGITAL ENVIRONMENT PART II

TheImagingProcessor

ADSLR’simagingprocessorworksbehindthescenes,turningthedatareceivedfromthesensor intoaviewabledigital image.Assuch, it isresponsibleforallthe computation of the data from the sensor, from the signal received by theADC(Analog-to-DigitalConverter)tothetransferofacompletedimagetothememorycard.

Thereisagreatdealofhiddenworkgoingonhere,notonlybecauseyouhave

no direct access to it (other than through themenu settings), but because theproprietaryalgorithms thatareat theheartof theprocessorarekeptsecret.Aswith software applications used on desktop computers, algorithms are themathematical procedures for performing actions, and those for imaging arecomplex. Not only that, but there are differences in the quality of theprogramming—whichcanonlybejudgedintheappearanceofthefinal image.There is more to do with image quality, in all its aspects, than the simplespecificationsofthesensor.

Inhigh-endcameras,thedesignofthesensorandtheimagingengineproceed

in tandem. Major camera manufacturers develop their own sensors andprocessors,andthisalonehelpstoimproveimagingperformance.Forexample,Canon,andmorerecentlysomeNikoncameras,currentlyuseCMOSsensorsfortheiradvantagesinspeed,powerconsumption,andcost,andaddresstheknownhigher noise level in twoways: through on-chip noise-reduction circuitry, andthroughnoise-reducingalgorithmsintheprocessor.Inanotherexample,Nikon’shigh-endmodelsuse theprocessor tocarry someof theburdenof suppressingcolor aliasing (false coloration),which is normally the job of the optical low-passfilterimmediatelyinfrontofthesensor.Increasingthebirefringentindexofthisfiltersuppressesthecolorartifactsbetter,butitalsolowersresolution.TheNikonfilterhasalowerbirefringentindexbecausetheimagingenginetakesonsomeofthetask.

A great deal of sensor technology involves compromise, and the imaging

enginecansolvemanyof theproblems.Youcanexperiencesomethingof this(inamuchmore limitedway)byshooting inRawformatandoptimizingyourimages later. It’s important not to try to make comparisons between DSLRsbased on the specifications that are usually published. Properly designed, asensorandprocessorcombinationwithamodestmegapixelsizecanultimatelyproduceimagesthathaveahigherresolutionandbettersharpnessthanalarger,moreprimitivesensor.

Theprocessorisprimarilyresponsibleforthefollowingtasks:

Thememorybuffer

Asframesarecaptured theyaremoved immediately to thebuffer, fromwheretheyaretransferredoneatatimeforprocessing.Buffersizehasanimpactontheshootingspeed(capturerate).

Creatingcolor

Pixels are sampled in relation to their neighbors, taking into account the colorarraypattern,tofillinthemissingcolorinformation.Colorgradationacrosstheimage needs to be smoothed, and color artifacts (false colors and fringing)removed.

Resolutionandsharpness

Anumber of aspects affect sharpness and resolution, including noise, aliasing(jaggies),andcolorartifacts.

Reducingnoise

Anextremelyimportantoperation,asthevariouskindsofnoiseareobstaclestocapturingacleanimagefromasensor.

Usersettings

Applyingthechoicesofferedinthemenutotheimage.

Imagecreation

Combiningallofthesensordataandprocessingtoproduceareadableimageinoneofseveralformats.

Compression

InthecaseofJPEGandsomeRawimages,applyingcompressionalgorithms.

Aprocessorengine

Aprocessorengine

Yourcamera’sonboardelectronicscanmakedecisionsforyou,shouldyouchoose,butitwillonlyeverbeabletoseethescenefromthepointofviewof

“averages”or“mostpeople.”

Updatingfirmware

Firmware is the termused todescribevariousprogramsalreadyencoded in thecamera, and itwill occasionally need updating as themanufacturermakes newversionsavailable.Therewillbeanoptioninthecameramenuthatletsyoucheckthefirmwareversioninstalled;makeanoteof thisandeveryfewmonthscheckthemanufacturer’swebsitetoseeif thereareupdates.Ifso,youmaybeabletoperform the operation yourself, depending on the make of your camera (withsome makes this must be done by an authorized service center). With user-installedupdates,paycarefulattention to the instructionsas this isanoperationthatcandamagetheprocessorifitgoeswrong.Inprinciple,thesequenceis:

1Downloadthefirmwareupdateinstallertoyourcomputerfrom

themanufacturer’swebsite.

2Copytheinstallertoablankmemorycard,usingeitheracardreaderorthecamera.

3Runtheinstalloperationfromthememorycard.Thistakes

severalminutes,andduringthistimethecameramustundernocircumstancesbepowereddown.

4Erasetheinstallerfromthememorycard.

CameraMenus

Becauseadigitalcameracanbesetupwithanoftenbewilderingnumberofuserpreferences, from significant shooting settings such as ISO sensitivity toconvenience options such as how files are numbered, all cameras need acomprehensivemenu.

Theoptionsaregroupedmoreorlesslogically,andatypicaldivisionisinto

set up, shooting, and playback,with an extra sub-menu for custom settings insomeinstances.

Some of the settings can be accessed via dial and button controls on the

camerabodyforeaseandspeedofoperation—thismaybeinsteadofbeingonthemenuor inaddition.Themenustructurevariesfrombrandtobrand,but islikelytocoverthefollowing:

StandardOptions

SetUp(MaybeSubdivided) Shooting Playback

LCDBrightness,timeon Fileformat Imagesizeonscreen

LCDBrightness,timeon Fileformat Imagesizeonscreen

Dateandtime Imagesize Datadisplayed

Language Whitebalance Zoom

Foldercreation,assignment ISO Delete

Addinformation Contrast Imageprotection

Mirrorlock-up Hueadjustment Hideimage

Formatcard Colormode folderselection

Videooutput Sharpen Slideshow

Cableconnectionprotocol Printspecification

Filenumbering

Noisereduction

Autofeatureson/off

EVsteps

Bracketsteps

Focussettings

GridDisplay

Flashmode

Assigndialsandbuttons

Shoottocomputer

ImageResolution

In the digital environment, an image’s resolution is governed simply by thenumber of photosites or pixels sited on the sensor: the greater the number ofpixels,themoredetailthesensoriscapableofcapturing.

However, it’s important not to think of resolution as the defining factor in

imagequality,asmorepixelsdon’tnecessarilymakeforabetterimage.It’sthequalityofthepixelsthatcount,andnotthequantity.

Camera sensor technology has evolved to such a point that today, most

DSLRsarecapableofproducinghigh-qualitytabloid-orA3-sizedprints;andforthevastmajorityofusthisisquitesufficient.However,forsomethisisstillnotquite enough, and sowe need to be aware ofwhat the limits are—andwhichtechniquesareavailabletohelppushtheenvelope.

Thewaytodealwithresolutionistoworkbackwardfromtheenduse.Whatlooksgoodona22-inmonitorwillnotnecessarilylookgoodasanormalprint,but if the screenview isallyouneed, thatdoesn’tmatter.Professionally, themain uses for images are prepress, display prints, and the Web. For bothprepress and display prints, digital files should be at twice the resolution atwhichtheywillbeprinted.Ahigh-qualityweboffsetpress,forexample,hasaline-screenresolutionof133and150,sothedigitalfileshouldbe300ppi.Thisisthestandard,defaultresolutionforprinting.

What ultimately counts, of course, is the number of pixels that goes into

making the image. Simply expressed, you need a 22MB file for an 8 × 10 inprint, and about the same for a full page in most magazines. Each cameramegapixelgives3MBofimage(thatis×3forthethreeRGBchannels),whichmeansthat7megapixelswilldothejobperfectlyanda6-megapixelcamerawillbe adequate. In termsofuse, a full page isoneof themostbasicprofessionalunits,while a double-page spread—twice the size—takes care of any possibleuse that an editorial clientmightwant tomake. Stock libraries are in the bestposition to know the demands of themarket, andCorbis, for instance, set thefollowingspecificationsfor theirownimages:40MBforeditorialsales,50MBfor commercial. These are, naturally, high professional specifications, but theprincipleis thesameasfor lessdemandinguses—calculatebackwardfromtheend-use.

All this is without attempting to improve resolution by upscaling. How

successfulthisisdependsonthealgorithmused,andthisishighlytechnical.Italso depends on how much deterioration you are prepared to accept. Nointerpolation method, however sophisticated, can equal a higher resolutionoriginal, but on the other hand the differences can be surprisingly small.Resolution,togetherwithsharpnessandnoise,arealsomattersofjudgment.Ifyou have a unique or important photograph by virtue of its content, imagequality takes secondplace.This regularlyhappens innews journalismand inart, too, and always has. Compare, for example, an early Bill Brandt print(manyaretechnicallysub-standard)withanEdwardWestonprintfroman8 × 10 innegative(Westonwasknownforhistechnicalperfection).

Digitalvs.film

Thisview(left)ofanoldwindmillonthebeautifulGreekislandofMykonoswasshotusingadigitalcamerawitha6-megapixelresolution.Theshotontherightwastakenimmediatelyafter(inthesameconditions)withatraditionalfilmcamera.Filmisbelievedtobeequivalenttoabout20megapixelsofdetail.

Resolution:digitalvs.film

Although it’s a question often asked, it’s almost impossible to compareresolution between digital and film because the measurement systems aredifferent,andbecausedigitalimagesareinprinciple“cleaner”thanfilmimages.Digitalimagescanbemeasuredbythedensityofpixels,butotherfactorscreepin,particularlythequalityofthelens.Theusualmeasurementispixelsperinchorpercentimeteralongastraight line.Afull-frame36 × 24mmsensorwith12megapixelswouldhavearesolutionof4048 × 3040pixels.

Digitalresolutionvsfilmresolution

Prepressanddisplayprints

Millimetres(wxh) Inches(wxh) MB@300ppi

A5 148x210 5.83x8.27 12.7

Magazinefullpage 190x260 7.5x10.1 19.5

USLetter 216x279 8.5x11 21.2

A4 210x297 8.27x11.69 25.5

8x10print 203x254 8x10 21.1

A3 297x420 11.69x16.54 51.0

A3+ 329x483 13x19 63.4

Magazinedoublespread 380x260 15x20.2 78

MonitorDisplay(pixels) Millimeters(wxh) Inches(wxh) MB@ppi

15-infullscreen(800x600)

305x229 12x9 1.4@66ppi


345x259 13.6x10.2 2.3@75ppi


406x305 16x12 3.5@80ppi

20-incinemadisplay(1680x1050)

432x269 17x10.6 5.1@100ppi

23-incinemadisplay(1920x1200)

495x310 19.5x12.2 6.6@100ppi

FileFormats

Digitalphotographycanbeseenasjustonebranchoroneelementofthelargersubject of digital imaging. Images have been created digitally, without digitalcameras,formany,manyyears,andforthisreasonanumberofdifferentwaysof organizing and storing digital images, known as file formats, has evolved,eachwithaparticularspecialty.

Some formats are better suited to one kind of image than another—for

example, graphic illustration with solid color and hard edges as opposed tophotographscontainingcomplexdetailandshading.Someformatsareaimedatdelivery—suchasfortheWeb.Bynow,afewstandardformatsareacceptedasusefulforphotographicimages,primarilyTIFF(TaggedImageFileFormat)andJPEG (Joint Photographic Experts Group). These two are readable andinterchangeablebyallimagingsoftwarethatdealswithphotographs.Inaddition,thereisthenativeapplicationformatthateachsoftwareprogramusesforitsowninternal workings, such as Photoshop's .psd files. These may or may not bereadablebyotherapplications.

Most SLRs offer two kinds of format: JPEG and Raw. JPEG, pronounced

“jay-peg,” iscomputing’s longest-establishedsystemforwriting images. Ithastwopowerfuladvantages: it isoptimizedfor transmitting images,andso is theuniversal formatfor theWeb,andalsocompresses imagesso that theyoccupylessdigital space.Theamountof compression is chosenby theuser—tomorethan 90%—and typical compression ratios are between 4:1 and 40:1. Thecompressionmethod used isDiscreteCosineTransformation,whichworks onblocksofeightpixelspersideand is“lossy,”meaning thatsomeof the imageinformation is thrownaway.This results in somedegradation,but this isquiteoftenundetectable innormal image reproduction. It’s important to run tests toassesswhatcompressionlevelsareacceptabletoyoufordifferentpurposes.

Forthebestimagequality,andtheabilitytore-adjustallthecamerasettings

aftertheevent,thereisRawformat.Thisisafileformatthatisuniquetoeach

makeofcamera,butwhattheyallhaveincommonisthatsettingssuchaswhitebalance,hueadjustment,sharpening,andsoon,arerecordedandkeptseparatelyfromtheimagedata.Thegreatadvantageofthisisthatanyofthesesettingscanbe altered during image editing, with no penalty in image quality. Anotherbenefitisthattheimagesareavailableatahigherbit-depth—typically12-or14-bit.ThedisadvantageisthatRawimagesneedextraworkwhenopeningtheminyoureditingprogram,whichmeansspendingtimeworkingonthem.

Bitsandcolors

Onebit(acontractionofbinarydigit)isthebasicunitofcomputing,andhastwostates,onoroff—blackorwhite.Abyteisagroupof8bits,andaseachofthesehas two states, one byte has a possible 256 combinations—that is, 256 valuesfromblacktowhite.AnRGBimagehasthreechannels,soat8bitsperchannelhasacoloraccuracyof256x256x256—that is,16.7millionpossiblecolors.Thisiswellbeyondtheabilityofthehumaneyetodiscriminate,andisstandard.Whythen,dohigher-endscannersandcamerasmakemuchofhigherbit-depths,suchas12-,14-,and16-bit?Thisisbecause,first,itmakessmootherandbettergraduatedtonesinagradient(suchasaclear,bluesky),andsecond,itimprovesthe accuracy of interpolation when images are altered or manipulated duringpost-production.

Note that it is usual to refer to bit-depth (that is the number of bits) by

channel, but occasionally you’ll see it described as the total, all-channel bit-depth—24-bit meaning 8 bits per channel and 36-bit meaning 12 bits perchannel.

Rawfiles

“Raw”isagenericnamefortheproprietaryfilesproducedbyallDSLR

cameras.Here,a.CR2file(Canon'sRawfileformat)isadjustedusingCanon’ssoftware,suppliedwiththecamera.ThealternativetoRawistohavethecameraoutputaJPEGfileinstead.Thiswillembedthecamerasettingsintheimage,reducingtheabilitytomakechangestothewhitebalanceaseasily,although

lessworkissubsequentlyneededtovieworprinttheimage.

Compressionvs.ImageQuality

Althoughstoragespace,primarilyintheformofmemorycards,isbecominglessexpensive, there are still advantages in being able to compress the data for aphotograph,provided that the image isnotnoticeablydegraded.Thekeywordhereis“noticeably.”

The raison d’être for JPEG in the camera’s menu is that it is both a

compressionmethodandafileformat,andthis isusuallytheformat tochoosewhenitisimportanttosqueezethemaximumnumberofimagesontoamemorycard.Inaddition,therecordingtimewillusuallybelessthanitisforaRawfile,andso the imageswillmove through theframebuffermorequickly—allgoodforshootinglargenumbersofimagescontinuously.

Compressing aRaw image is a differentmatter. The space saving is in the

orderof50%,but thereisa timepenalty,andthisbecomesimportantoncethebufferhasfilled.Thiscreatesapotentialproblemwhenchoosingwhetherornotto beginwith compressed files—youwill need towait for the image(s) to beprocessedbeforeyoucanchangetouncompressedonthemenu.

Compressionanddegradation

Mostcamerasofferanumberofcompressionlevels,rangingfromhightolow,and usually expressed along the lines of Basic, Normal, and Fine,with Basicoffering the highest compression/lowest image quality, and Fine the lowestcompression/highestimagequality.However, theresultingfilesizesdependontheimagecontent.IfyouaregoingtomakesignificantuseofJPEGformat,itisessential to run your own tests and judge what degradation you are happy toaccept. The images will all be degraded slightly, but the key is to choose asetting thatmakesnovisibledifference. Inpractice,mostpeoplecandetectnoqualitylossatnormalviewingdistances.

Compression:losslessvs.lossy

Compression can be applied in one of two forms—lossless or lossy. As theirnamesimply,onecompressesthefilesizewithoutdiscardinganydata(workinginsteadbywritingthedatainamoresuccinctway),whiletheotherthrowsawaysome of the information. Compression is sometimes described as a ratio (e.g.1:4),asapercentageofreduction(e.g.80%),orasapercentageoftheoriginalfilesize(e.g.20%).Thelasttwoareeasilyconfused.

The leading lossless compression system isLZW (named after its inventors

Lempel-Ziv-Welch), used with TIFF images, and the amount of space saveddependsontheimagecontent.Typically,filesizesarereducedtoabout40%to50%, though less in high bit-depths. Raw formats can also be compressedwithout loss, using camera manufacturers’ proprietary methods. Onedisadvantage of lossless compression is that it can add substantially to therecordingtime.

Lossy compressiondoesdegrade the image, but not necessarily to thepoint

whereitcanbeseen.TheleadingcompressionsystemisJPEG,andtheamountofcompressioncanbeselectedbytheuser.In-cameracompressionisnormallylimited toachoiceof threesettings,whichvaryamongcameramakes,butaretypically1:4,1:8,and1:16.

Rawvs.JPEG

ThephotographontheleftistheoriginalimageasphotographedinRawformat.Ontherightisthesameimagecompressedatthehighest-qualitylevelinJPEG

format.Atthissizethetwoimagesareindistinguishable.

MeasuringExposure

Theabilitytoreviewyourimagesinstantlyusingthecamera’srearLCDscreenhasmeantthatgettingaccurateexposurehasneverbeensoeasy.

Even if you insist on using Manual rather than Auto exposure, it is still

quickertoguessthesettings,shoot,andchecktheresultthantoworkthemoutcarefully.

If this sounds less than conscientious, remember that another set of skills isrequired—judging good exposure by means of the histogram and clippedhighlight warning. As with film SLRs, most cameras offer a choice ofmatrix/multi-patternmetering,center-weighted,andspot readings.Eachhas itsuse, but again, it is the result on the LCD display that really demands yourattention.

Themetering principles are largely the same as for film cameras, with the

possibilities of extra precision because each pixel can bemeasured. There arethreeprincipalmeteringsystemsusedinDSLRs,anddifferentmodesthatallowyou to prioritize shutter speed or aperture and create custom combinations ofboth. Exposure compensation and exposure bracketing (in which bursts ofconsecutive frames are exposed at changing increments over and under themetered reading) are standard. Advanced measurement in high-end camerastakesaccountnotjustofbrightness,butalsocolor,contrast,andtheareafocusedon, all in an effort to second-guesswhich parts of the scene you are likely towantaccuratelyexposed.

Although instant review means that you can retake the shot if you’re not

happy with the exposure, there may be times when you don’t have a secondchance,sogettingitrightfirsttimeisalwaysanimportantconsideration.

Spot

The spotmeteringmode inmostDSLRs allows you tomake readings from averysmallcentralarea—oftenlittlemorethan2%oftheimagearea.Thisisthein-cameraequivalentofaspotmeter,inwhichyoucanmeasureverysmallpartsof the scene. This is especially useful if you want to base the exposure on aparticularprecisetone.

Forthisscene,takingaspotreadingfromthebrickbuildingpreventstheshaded

foregroundorbrightskyfrominfluencingtheoverallexposure.

Center-weighted

Center-weightedmeteringgivesprioritytothecentralareaoftheframe,onthereasonableassumptionthatmost imagesarecomposedthatway.Lessattentionispaidtothecornersandedges.Theprecisepatternofweightingvarieswiththemakeofcamera,andsomemodelsallowyoutochoosedifferentweightings.

Acenter-weightedmeterreadingeliminatesmuchoftheskyandforeground,

givingagoodtonalrange.Notethatoverall,theexposureislighterthanthespotmeterreadingonthepreviouspage.

Center-circlemetering

Thecenter-circlemeteringmodecanbeseenasamoreconcentratedvariantofcenter-weightedmetering,usingadefinedcircleinthecenteroftheframe.Thisisagreatsolutiontoshotswherethesubjecttakesupmuchoftheframe,thoughyou might find it more appropriate to use spot metering when composing adifferent kind of image. If youwere placing a figure according to the rule ofthirds,forexample,thiswouldbelessthanideal.

Herethesubjecttakesupmuchofthecenteroftheimage,soalargercirclethan

spotmeteringisappropriate.

MatrixorEvaluativemetering

Thematrix, segmentorevaluativemeteringmode found inDSLRs isahighlysophisticatedmeteringsystem thathas twocomponents.One is thedivisionoftheframeintosegments,whichareeachindividuallymeasured.Thesecondisadatabase ofmany thousands of picture-taking situations based on either actualshot images or (less accurate), theoretically derived scenes. The pattern ofexposure readings is comparedwith those in the database and the appropriate

algorithmisapplied.Atitssimplest,ifthereisamuchbrighterstripacrossthetopofahorizontal frame, thiswillbeassumed tobe theskyand theexposurewillbeweightedmore to thedarker areabelow.Equally, a compactdarkareaclose to the center of an otherwise light scene will be assumed to be theimportantsubject,andtheexposurewillbeadjustedforthat.

Thematrixrecordsanaveragefromareasoftheimage.Herethedarkareasinthetopoftheimageandlightonesintheforegroundareclearlyshowninthe

matrix.

ControllingDynamicRange

Compared to film, digital sensors are much more sensitive to light. Thissensitivitycanleadtoproblemswhenthereisawidetonalvariationinthescene—inthesecontrastinginstancesit’softendifficultforthesensortorecorddetailinthehighlightareas.

The larger the photodiode, the greater the sensitivity and the wider the

dynamicrange,butthisisinconflictwiththeneedforsmallerphotositesonthesensor to increase the resolution. The photodiode must fit within the totalphotositearea,andstill leavesufficient roomforothercomponents.Moreover,typicalphotodiodesstillreachsaturation(thatis,afulltonalrange)fasterthanisideal.

Blockedhighlights

Inhighlightareas,digitalsensorstendtocompareunfavorablywithfilmbecauseoftheirlinearresponse.Thetypicalfilmresponsetoexposureshadesoffatbothendsofthescale,hencethefamiliarS-shapeofthecharacteristiccurve.

Practically, thismeans that film has some latitude in the highlights and the

shadows as its response is not linear.Digital sensors, however, have a linear,straight-line response, and this results in easily blocked highlights. Anyonefamiliarwithfilmisusedtotherebeingsomehintofdetail inmosthighlights,butthisisnotsowhenusingdigital.Oncethechargeinthephotodiode“well”isfilledup,thehighlightsareblocked,anditisasifyouhaveaholeintheimage—or“triple255”whenmeasuredinRGB.

Dynamicrange:filmvs.sensor

Dynamicrange:filmvs.sensor

The shape of the red curve shownhere, gives us a visual clue as towhy filmappears to have a greater dynamic range when compared with a sensor. Thecurve plots the brightness of the image (on a vertical scale) against thebrightness of the light striking it (on a horizontal scale).With both film andsensors, most of the middle tones in a scene fall on a straight line—notsurprisingly called the “straight-line section”—meaning that the imagebrightnessmarches instepwith thesubjectbrightness.Ateitherend,however,filmreactsinaspecialway.Itfallsoffinagentlecurveintheshadows(lowerleft) and highlights (upper right). For example, in the highlights, twice theexposureresultsinlessthantwicethebrightness,whichisveryuseful,becauseit tends to hold highlight detail. The same applies to shadow detail. Sensors,however,inherentlylackthissmoothingoutofthecurve.

Inanormalphotographofanormalscene, theshadowsareat the lower left

(the“toe”)and thehighlightsat theupper right (the“shoulder”),withmostofthe tones in themiddle, the “straight-line portion” of the curve. Significantly,this means that with film, highlights do not easily blow out—increasing

exposurehaslessandlesseffectonthedensity.Inotherwords,withincreasingexposure to light, film response starts slowly (shadows) and finishes slowly(highlights).Photodiodesonasensor,however,lackthiscushioningeffect.Theyreachsaturationsteadily,atwhichpointthereisnohighlightdetailwhatsoever.In other words, film tends to be more forgiving of under-and overexposure,particularlythelatter.

Histogramsanddynamicrange

Thisimageisoverexposed,whichhasledtoclippedhighlights.Thehistogramrevealstheseintheformofatallspikespillingoutoftherangeatthefarright—

toomuchoftheimage,inotherwords,iswhite.

Inthisalternativeexposure,thehistogramshowsthehighlightsnowfallwithintherangeofthehistogram,sotherearenoareasintheimageinwhichdetail

hasbeenclipped.

THE D IGITAL ENVIRONMENT PART III

RealWorldDynamicRange

Despite often receiving requests from the photographic press and otherreviewers,cameramanufacturersrarelyreleasedynamicrangefigures,primarilybecauseit’sveryhardtocreateanyreallymeaningfulmeasuringtestastherearesomanyfactorsthatcomeintoplay.

Onewaytoappreciatethisistomakeyourowndynamicrangetest,asshown

here.Typically, thereare just-measurable,butvisually insignificantdifferencesattheshadowendofthescale.

When shooting, payparticular attention to thehistogramdisplay and to any

availablewarningdisplaysforclippedhighlights.Aslongas thehistogramfitscomfortably within its left-to-right scale, you will have an average-to-lowcontrastimagethatcanalwaysbetweakedlater.Thedangerliesinahistogramthatspillsoverleftorright,orboth.

Adynamicrangetest

Begin the test by photographing a gray card or any neutral blank surface at arange of exposures, under consistent lighting. First, establish themid-point byshooting at an average setting, either manually or automatically. Then takesubsequent frames at equal intervals darker and lighter, in at least six steps ineachdirection,under-andoverexposed.Forgreateraccuracy,makethesestepsatone-halforone-thirdƒ-stopintervals,althoughforsimplicity,theexamplehereisatone-stopintervals.

In Photoshop, assemble the images in order, and label each of the steps asshown.Usethecursorandinfodisplaytomeasurethevalues.Findandmarkthestep on the left-hand side thatmeasures 5 (anything less is effectively black).Find and mark the step on the right-hand side that measures 250 (anythinghigheriswhite).Thesetwoextremesdefinethedynamicrange.Inthisexample,aNikonDSLRcapturesninedistinctsteps—thatis,arangeof8stopsor256:1.

The test, however, reveals some other important characteristics.One is that

themid-pointof thisrange isnot theaverageexposure,but insteadalmostonestopunderexposed.Notonlythis,buttheincreasesinexposurereachsaturation(255)morequicklythanthedecreasesreachpureblack.Thisconfirmswhatwealready expect in terms of a sensor’s linear response. Note, though, that theresponseattheshadowy,underexposedendofthescale,isnotexactlylinear,buttails off more gently, as does that of film. All of this suggests that for thisparticularcamera, itwillbesafer tounderexpose incontrastyconditionswhileshootinginRawformat.

Checkingchannels

Clippingwarningsmay come into effect when just one or two channels havebecomesaturated,andthisisnotadisaster.Thankstointerpolation,evenblownhighlightsinafullysaturatedphotositecanbegivenavalueofsomeusebytheon-boardprocessor.Thisisbecauseeachphotositemeasuresoneofthreecolors,and interpolation isused toassignfull-colorvalues to it.SomeDSLRsdisplayindividualchannelhistograms,withwhite (thesumofall three)superimposed.

The danger iswhen all three channels are clipped.Here, red is saturated, butgreenandbluearestillwithintheframe.

Highlightwarnings

Twovaluablein-cameradisplaysofoverexposedareasarethehistogramandahighlight indicator.When the right-hand (bright values) edgeof the histogramappears like this, at least some of the tones are solidwhite. Amore insistentwarning available on some cameras displays the highlights with a flashingborder.However, you should always check these in-camera clippingwarningsagainst thevalues that appearwhenyouhaveopened the image inPhotoshop.Typically, camera manufacturers err on the side of caution, and the clippedhighlights displayed in the camera’sLCDare likely to be at a value less than255.Inotherwords,evenwithsomepartsoftheimageapparentlyclipped,theremayactuallybesufficientinformationtorecoverandedit.

Anon-camerahistogramdisplaycanrevealclippedhighlights.

Alternatively,theremightbeaflashingwarningthatissimilartothis.

CopingwithContrast

Theoptimumexposureformostimagesiswhenthereisanevenspreadoftones,from dark shadows to bright highlights—or in other words, a fully expandedhistogram.

Lowcontrastpresentsnodifficultiesatall,otherthanperhapsjudgment,asit

is a simplematter to drag thewhite and black points out to the edges.High-contrast images,on theotherhand,arealways indangerofbeingclipped,andimage-editingtoolsneedsomeimagedatatoworkwith.Thismeansgettingtheexposureright—notnecessarilythesamethingasgettingitaveraged.

High-contrast scenes always need special care, even more so than with

transparencyfilm.Aswesawonthepreviouspages,theresponseofasensortolight is linear.Crudelyput, it fillsup toabsolutewhitemorereadily thanfilm,and thismeansbeingconstantlyonguardagainst clippedhighlights. Indigitalimaging,theseareusuallymorecriticalthanclippedshadows,fortworeasons:oneisthatevenaverylittlelightgeneratessomeresponseatthedarkerendoftherange,theotheristhatperceptuallymostofwhatcatchesourattentionisinthebrighterareas.

Reducingcontrast

IfyouareshootingJPEG,contrastandexposurearetheonlyin-cameracontrolsthatwillhelpyoutoreducecontrast.Loweringthecontrastsettingissensible.Itis safer to underexpose the bulk of the image to preserve highlights, and thenlighten the shadow areas during image-editing.Bracket exposures if you havetime,bothforsafetyandinordertobeabletocombineexposures.Addingfill-inlighting, even if this is just from the camera’s built-in flash, will also reducecontrastbyraisingthevaluesoftheshadows.

Knowinginadvancethatyoucanoptimizetheimageonthecomputer,oneofthe safestprecautions is toavoidclippedhighlights, evenat theexpenseofanoverall darker image. In conditions that you know to be contrasty, pay mostattention to the clippedhighlightwarningon theLCDdisplay. If the situationallowsyoutime,makeatestexposuretocheckthisfirstandthenswitchtothehistogramtomakesurethatnothinghasbeenclippedattheshadowend.Iftheentirehistogramiswithin thescale,even if thebulkof it isshifted toward theshadows,thenyoucanusuallyoptimizeitsatisfactorily,particularlyiftheimageisinahighbit-depth.

Formoreextremesituations,inwhichnoexposuresettingwillavoidclipping

atoneendortheother,thereisanimage-editingsolution.Itneedsastaticsceneand a locked-down camera—on a tripod, ideally. Shoot three ormore frames,adjustingtheexposureeachtimetoensurethatbothhighlightsandshadowsarecaptured accurately by at least one frame. Combine the images during post-productiontocreateahigh-dynamicrange(HDR)imagestyle.

Assessingcontrast

The importance of dynamic range and contrast depends on the form of theimage. The tonal range of the entire image may be different from the rangewithinasmallpartthatyouconsiderimportant.Inthecaseofthemodernofficeinteriorhere,therearetwodifferentinterpretations.Ontheonehand,youmightwanttoretainshadowdetailinthelargeouterpartoftheimage,inwhichcaseyou would consider the overall contrast. On the other hand, you couldlegitimatelyignorethedarksurroundandexposejustforthebrightlylit,glassycorridor in the center. The tonal range within is one stop less than the entireimage.

Rawformat

Indifficult, contrasty lightingconditions,by far thebest courseof action is toshootRaw.Thismakes thecontrast settings irrelevantas theycanbe revisitedlater, and also allows higher color bit-depth, which in turnmakes it easier tomakestrongadjustmentswithoutseriouslydamagingtheimage.Typically,youcanexpect tobeable toadjust theoriginalexposurebyupto twostopsdarkerand fourstops lighter,whileat thesame timechanging thecontrast.However,Raw format will not help completely lost highlights. Once photodiodes havereached saturation, no amount of processing can recover the data. The image-editing technique of combining two exposures, one dark and one light, alsoworkstoanextentinRawformatwithasingleexposure.FirstopentheRawfileand alter the settings to maintain highlights, even at the expense of losingshadowdetail.Savethisversion,thenopenthesameRawimageasecondtime,adjustingthesettingstopreserveshadowdetail.Then,finally,combinethetwoversions.

What’sthe“right”exposure?

Thefirstimagebelowappearsatfirstglancetobebetterexposedthanthelowerimage,becausethehistogramshowsanevenspreadoftones.However,someofthehighlightsareclipped,andthesewillbeunrecoverableinimage-editing.Theexposure for the lower image (one ƒ-stop less) produces an image that looksdarker, but the shadows aren’t noticeablymore clipped, and the highlights arealsobettercontrolled.

Lenses

The unparalleled flexibility of a DSLR is down to the fact that you can useinterchangeablelensesofvaryingfocallengths,fromfish-eyetosuper-telephoto.

Thegoodnewsisthatifyouhavealargecollectionofexistinglensesforyour

film SLR, it’s more than likely that you can use them on the same brand ofDSLR, even though some new camera featureswill be unavailablewith oldermodels of lens. This is all straightforward, except for issues related to thesmallersizeofsensorsand,atadeeperlevelofperformance,thepixelsize.

Asitstands,therearebroadlytwosizesofsensorscommonlyusedinDSLRs:

APS-C/DX sensors that are smaller than 35mm film and “full-frame” sensorsthatarethesamesizeas35mmfilmandusedinprofessionalDSLRs.ThesmallsizeoftheAPS-C/DXsensorsaffectsawholeraftofimageproperties,includingsomeofthestandardsthatphotographersareusedto,suchasusingfocallengthas away of describing the angle of view. 24mm, for example,was a kind ofshorthand for thedynamics of one typeofwide-angle image, but as a smallersensorcovers lessof the imageprojectedonto it thanwoulda full24 × 36mmframe,thepictureangleisless.

Practically,thismeansthatastandard50mm“wideangle”lensmountedona

digitalcamerawithasensorareaof23 × 15mm(APS-C)behaveslikealensofaround78mm focal length on a full-frame, or 35mmcamera. Similarly,wide-anglelenseshavelessofawide-angleeffect,whiletelephotosappeartobemorepowerful.

Depth of field is also affected (it is increased), and this has various

consequences all the way back to sharpness. Sharpness is not a precisedefinition, but depends partly on resolution and partly on perception. Highcontrast, forexample, increasesapparentsharpness.As the image ismagnifiedmore, depth of field increases. This is generally good to have, but a problemwhen you need the extremes of selective focus, as in some styles of foodphotography,forinstance.

Thereisalower“quantum”limitonsharpnesssetbythesizeoftheindividual

pixels on a sensor.A24 x 16mm sensor that images 3,000 × 2,000pixels, forexample, has photosites measuring 0.008mm (8µm). As semiconductortechnology reduces this size further, it increases the demands on lenses.Mosthigh-qualitylensesoptimizedforfilmcanresolvetoabout10microns,whilethepixel pitch on newmulti-megapixel sensors can be as low as 5microns.Oneimportant effect is that color fringes caused by chromatic aberration must besmallerthanthesizeofapixel.Oldlensesoftenfailinthis,whileafurtherissueiscornershading,althoughthiscanbecorrected.

Wide-angleimplications

BecauseanAPS-C/DX-sizedsensor isaround2⁄3 thesizeof35mmfilm,youroldlenseslose1⁄3oftheircoveringpower.Onthepositiveside,thismeansthattelephoto lenses have that much greater magnifying power when fitted to aDSLR,butyou loseoutat thewide-angleendof thescale.This limitationhasforced manufacturers to introduce new, wider lenses. If dedicated to digitalcameras, these can be very wide indeed. A 12mm lens, for example, is theequivalentofan18mmlenson35mmfilmorafull-framesensor.

Multi-megapixelsensorsaremakingnewdemandson lenses,with the result

that cameramanufacturers arenowdesigning lensesoptimized fordigital.Notonly are high-density sensors less tolerant of poor resolution lenses, but theresolutionneedstobesmallerthantheactiveareaofthephotosite.Usinganold,film-optimized set of lenses on a new digital body may sound like a good,economicalidea,butthetrade-offislikelytobelowerimageresolutionthanyoucould be getting. The other problem is called “cornershading.” Light from anormalcameralensdivergestocoverthefilmorsensor,strikingtheedgesatanangle—and with a wide-angle lens, this angle is more acute. This hardlymattered with film, but as the wells on the sensor are all parallel, light raysstrikingthefurthestphotosites—atthecorners—maynotfullypenetrate,causingshading. This again suggests a change in lens design—one solution is a rear

element combination that refracts the diverging light rays back to beingmorenearlyparallel(a“telecentric”lensdesign).

“Digital”lenses

For some time, lensmanufacturershavebeenproducing lenses specifically forAPS-C/DXcameras.Featurescanincludethefollowing:nomechanicalaperturering, apochromatic (high color correction) glass, very short focal lengths forwide-angles,andasmallimagecirclethatcoversnomorethanthesensor.Thislast feature enables lenses designed specifically for smaller sensor sizes to besmaller,lighter,andhavelargerzoomratios.

Nikon12–24mmzoomlens

EFL

EFL

Sincetheadventof35mmcameras,lenseshavebeendescribedashavingfocallengthssuchas20mm,50mm,and180mm.Theselabelsaresoembeddedintheworking languageofphotographythat theywillcontinue tobeusedfora longtime.Indeed,forfull-frameDSLRs,theyremainperfectlyvalid,butthevarietyofsmallersensorsizesleavesuswithoutaconvenientwayofdescribingalens’smain characteristics—its angle of view and magnification. One solution is“equivalentfocal length”(efl),whichiswhat the lenswouldbe if the imageitdelivered were on a 35mm frame. Efl is found by dividing the diagonal of a35mm film frame (43.3mm) by the diagonal of the camera’s sensor, thenmultiplythelensfocallengthbythis.Thesearetheequivalentfocallengthsfortypicalsensorsizes:

ActualFocalLength efl23x15mmsensor efl24x16mmsensor

12mm 18.9mm 18mm

17mm 26.8mm 25.6mm

20mm 31.5mm 30.2mm

28mm 44.1mm 42.2mm

35mm 55.2mm 52.8mm

50mm 78.8mm 75.4mm

100mm 157.6mm 150.8mm

200mm 315.2mm 301.7mm

300mm 472.8mm 452.5mm

Aseriesoffocallengths,from20mmatthewidestendto300mmatthelongest.(Theintervalsare28mmefl,35mmefl,50mmefl,100mmefl,and200mmefl.)

Bokeh

Akeyaspectofcontrollingdepthof fieldoften involvesdeliberately throwingcertain parts of the image out of focus. The overall appearance of the out-of-focus parts of an image, judged esthetically, varies according to the aperturediaphragm and the amount of spherical aberration correction, among otherdesign features. It comes into play chiefly with telephoto lenses used at wideapertures,anditparticularlyconcernsportraitphotographers.

This has become fashionably and unnecessarily known in theWest by the

word “bokeh” (pronounced bok-e, with a short, flat e), which in this contextmeans simply “out-of-focus.” Amajor influence is the shape of the aperture,which tends to be replicated in specular highlights—polygonal inmost cases,while amirror lensproduces rings.Themoreblades to the aperture, themoresphericalthesesofthighlightsbecome.Theopticsalsohaveasubtleeffect.

Thisclose-upportraitwasshotusinga135mmlenswithawideaperture.Theroundshapeoftheout-of-focuselementsinthebackground—thebokeh—are

causedbytheshapeoftheaperturebladesinthelens.

Dofiltershaveaplaceindigitalphotography?

Now that certain image corrections, suchaswhitebalance andhue correction,are taken careofdigitally, there is no longer anyneed for light-balancing andcolorcorrectionfilters.Threefront-of-lensfiltersdo,however,remainvaluable:

Ultravioletfilter

Reduces haze effects by cutting someof the shortwavelengths.Also valuableforphysicallyprotectingthefrontlenselementfromscratching.

Neutralgrads

These filters can be raised or lowered in their holder androtated.Withalandscape,alignthetransitionzoneofthefilterwiththehorizon.Althoughskiescanbedarkenedlaterduringimage editing, a grad filter at the time of shooting preservesmoretonaldatawhenpositionedsothat itcovers thebrighterpart of the frame. Neutral grads are available in differentstrengths—for example,ND0.3darkensby1ƒ-stopandND0.6by2ƒ-stops.

Polarizingfilter(circular)

Cuts polarized light, so is particularly useful for darkening blue skies (moststrongly at right angles to the sun) and reducing reflections fromglass,water,and other non-metallic surfaces. Also has a strong haze-cutting effect.Polarizationcannotbereplicatedbysoftware.

Theleftsideofthisimageshowstheeffectofpolarization.Notehowdarktheskyis(makingthecloudsappearwhiter)comparedtothepaler,non-polarizedright

sideoftheimage.

Cuttingdownlensflare

In very bright conditions, light can enter the lens and reflect around the lenselements,ratherthanbeingdirectedtothesensor.Knownasflare,thislightcanappearasalineofbrightpolygonsstretchingawayfromthebrightlightsource(suchasthesun)orasanoveralllightfog.Flarecontrolmeansshieldingthelensfromanybrightlightoutsidethepictureframe,andtheidealsolutionistomaskdowntheviewinfrontofthelenstotheedgesoftheimage.Fittedlenshoodsdoafairlygoodjob,particularlyiftheyareshapedtosuittheimagearea,buttheyhave thedisadvantageof being close to the lens andon a zoom lens they canonlymaskaccuratelyatthewidestangle.

A professional adjustable lens shade is better, though slower to use, andtypically features an extendable bellows and/or movable masks. This isparticularlygoodforthespecialcaseinstudiophotographyinwhichthesubjectis against a large bright background. The bright surface that surrounds thepicture area creates akindof flare that is not immediatelyobvious, butwhichdegradestheimagenevertheless.Finally,toshieldagainstpointsourcesoflight,whether thesunorstudiospots, themostpreciseshading isatadistance fromthe lens, using a black card or flag, or even your own hand held just out offrame.

•Use a lens shade—either a fitted shadedesigned for theparticular lens, or abellows shade that can mask right down to the image area. Many telephotolenseshavebuilt-inshadesthatslideforward.

•Checktheshadowonthelens.Ifthecameraisonatripod,standinfrontandholdacardsothatitsshadowjustcoversthefrontofthelens.

•Keepthelensclean.Afilmofgreaseordustmakesflareworse.

• Remove any filter. Filters, however good, add another layer of glass thatincreasestheriskofflare.

• Use a properly coated lens. High-quality, multi-coated lenses give less flarethancheaperones.

Lenshood

Bellowsshade

Flagandarm

Standardvs.wide-anglelenses

Thereisastandardfocallength;broadlyspeakingitisthelengththatprovidesaview that corresponds with what we see with our eyes—neither wide norcompressed, but in reality, it is imprecise.The usual rule of thumb is that thestandardfocallengthisequaltothediagonalofthefilmframeorsensor.Fora35mm frame that would be 43mm, but by convention 50mm has become“normal”with35mmfilm.Thede-restrictionofformatwithdigitalcamerasandreplacementofprime lenseswithzoomserodes this50mm“benchmark.”Thisis, in any case, a perceptual issue, and a realistic guide is the focal length atwhich the view through the viewfinder and the viewwith your other, unaidedeyearethesame.

Olympus11–22mmwide-anglezoomlens

Olympus11–22mmwide-anglezoomlens

(Left)50mmefl.(Right)A20mmefllens(inthiscase,13mmonaNikondigitalcamerawithasensorsizesmallerthan35mmfilm)hasadiagonalangleofviewofjustover90º.Theverticalcropinsidethisframeisthe45ºcoverageofa

50mmeflstandardfocallength.

20mmefl

MacroandClose-upLenses

By its very nature, macro photography (and to a lesser degree close-upphotography)hasalwayscausedchallengesforlensmanufacturers,andthisisnodifferentfordigitalcameras.

What has changed is the ease and precision of shooting at close distances,

because the uncertainties introduced by the various optical calculationsdisappearwiththeinstantfeedbackfromaDSLR.

DSLRsareidealformacroshooting,becausetheon-boardprocessingof the

imagecandealwith theproblemsofcontrast,color,andevensharpness.Also,byshootingdirecttoacomputer,youcanusethelargermonitortocheckdetailand tolerances. Moreover, with DSLRs that use a sensor smaller than 35mmfilm,onlythecenterofthelensisusedforimaging,andthisisrelativelyfreeofmany aberrations, including spherical aberration, which is worse at closedistances.

Macrodemands

Macrophotographymakesspecificdemandsonlenses.Sphericalaberration,forexample,ismoreprominent.Thisiscausedbytheincreasingangleofcurvaturetowardtheedgesofthelens,whichaltersthefocusslightly.Stoppingdownthelenshelpstoreduceitbecausethesmallerapertureallowsonlythecenterofthe

lenstobeused.

Thetwomostusualmeasurementsinclose-upimagingaremagnificationand

reproduction ratio, and they are linked.The commonly accepted starting pointfor close-up photography is between 0.1× magnification (1:10 reproductionratio,meaningtheimageisone-tenthlife-size)and0.15×magnification(1:7).At1.0×,theimageislife-size(1:1).Acrossthisrange,asthelensracksforwardinits barrel, the light‑reaching the sensor falls off increasingly, but autoexposuretakescareofthis.Photomacrography,commonlyknownasmacro,extendsfrom

1.0×to20×(a1:1reproductionratiotoabout20:1),atwhichpointthelawsofoptics make it more sensible to use a microscope. (Macrophotography,incidentally, means something else entirely—photography on a large scale.)Photomicrographymeansphotographyusingamicroscope,forwhichthereareanumberofoff-the-shelfsystemsforattachingaDSLRcamera.

The most efficient method of magnifying an image is to extend the lens

forward,awayfromthesensor,thewaythatmostlensesarefocusedfornormalphotography.However,forclosefocusing,thelenselementsneedtomovemuchfurtherthannormal,becauseoftherelationshipbetweenthetwoconjugates(thedistancesfromtheprincipalpointofthelenstothesubjectononesideandtothesensor on the other).When the subject ismore than about ten times the focallengthdistant,theimageconjugatestaysmoreorlessthesame.Closerthanthis,however, and the image conjugate gets significantly larger. When the twoconjugatesareequal,youhave1:1magnificationandalife-sizeimage.

Thismakeslensmanufacturealittletrickybecausemostlensesperformbest

whensubjectsaredistant,butnotsowellwhen theyareclose.Asidefromthemechanics of moving the glass elements inside the lens barrel, the sharpnesssuffersandaberrationsgetworse.Atruemacrolensistheidealsolution.

Conjugates

The lens focuses each point on the subject to an equally sharp point on thesensor (which is on the imageplane). In photography at normal distances, theobjectconjugate ismuchlonger thanthe imageconjugate,whichchangesverylittle as you focus. Butwhen the subject is close, the two conjugates becomemoresimilarinlength.

Backtofrontlens

Mostcamera lensesaredesigned toperformwellwhen the imageconjugate issmallerthantheobjectconjugate.Atmagnificationsgreaterthan1×(1:1)thisisno longer true, and the image is better when the lens is reversed. For opticalreasons, this only works well with lenses of a symmetrical design and withcertain retrofocus lenses. Once reversed, the lensmust then be stopped downmanually.

Close-upandmacrolensesandaccessories

Close-focusinglenses

Modernlensdesignmakesitpossibleforstandardlensestofocusdowntoclosedistances.Thequalityoftheimageatclosefocus,however,variesfrommaketomake,andislikelytobecompromised—atleastincomparisontoatruemacrolens.Theperformanceofastandardlenscanbedisappointing.

Macrolenses

These are designed to deliver their best image quality at close distances, andacceptablequalityatnormaldistancesuptoinfinity.Somemanufacturersofferachoice of focal length between normal and long-focus; the advantage of thelongermacrolensesisthatyoucanusethematagreaterworkingdistancefromthe subject,which is useful, for example,with insects thatmightotherwisebefrightenedoffbyacloseapproach.

Extensionringsandtubes

A standard method of increasing magnification is to increase the distancebetweenthelensandthesensor,andthesimplestwayofdoingthiswithanSLRistofitaringortubebetweenthelensandthecamerabody.Thefocallengthofa lens is the distance between the sensor and the lens when it is focused atinfinity. Increasing this distance by half gives a reproduction ratio of 1:2.Doubling thedistancegives1:1, and soon.Some, but not all, extension ringsandtubeshavelinkagesthatconnecttheapertureandotherlensfunctionstothecamera.

Extensionbellows

Flexible bellows moved by rack-and-pinion offer fine control overmagnification, and are normally used for extreme close-ups. Becausemagnificationisrelativetothelensfocallength,theshorterthelensattached,themorepowerfultheeffect.

Extensionbellows

Diffraction

Anotheropticalissuethatismorerelevanttomacrothannormalphotography,isdiffraction.Thisoccurswhenanopaqueedgeobstructsthelightpath,causingittobendslightlyandspread.Thisiswhattheaperturebladesinthediaphragm

insidealensdo,andtheresultisunsharpness.

StitchingImages

Digitalphotographyhasmadestitchingtogetheroverlappingframes—tomakeasignificantlylargerimage—arelativelystraightforwardtechnique.

Thetechnique’smostcommonuseistocreatepanoramas,butthereareother

applications. Although this is strictly speaking a software matter, it is highlyrelevant to lensfocal lengthandcoverage,because ineffectyouarecreatinga

wider-angleview.

Also,withthiskindofimaging,eventhoughitmakesheavyuseofsoftware,

allof theplanningneeds tobedoneat the timeofshooting—photographyandstitchingareseparateoperations.Thisisknownasplanarstitching,andtheresultisanormaldigitalimage,savedusuallyasaTIFForJPEG.Aquitedifferent,butvery importantalternative iscylindricalor spherical images,whichareusuallysavedasQuickTimemovies.

In principle, you could combine the overlapping images manually in

Photoshop,buttherearetwoobstacles.Oneisthatasyouturnthecameratooneside for the adjacent frame, objects in the frame change their shape slightly—noticeablysowithawide-anglelens—sothateachframelaterneedsadistortionadjustment. The other is that it is difficult to blend the brightness of adjacentframes when there are large, smooth areas such as a sky—again, particularlywithwide-angle lenses.Stitchersoftwaredoes thisautomatically, in twosteps.Thesoftwarefirstfindsanumberofcorrespondingpointsinadjacentimagesandwarpstheimagessothattheyfitperfectly,towithinonepixel.Itthenequalizestheimagessothatthereisaseamlessblendofbrightnessattheedges.

Tilingforhigherresolution

Shootingasequencehorizontallycreatesapanorama,withtheaddedadvantageofmakingalargerimagefilethannormal.Thisis,indeed,theeasiestsolutiontocreating a high-quality large image file—take any scene that you have justphotographed, switch to a longer focal length, and photograph it again insections,beforeassemblingtheseintoahigher-resolutionversion.Thisisknownastiling.Itcanalsofulfillanotherobjective,whichistoincreasetheFOV(fieldof view). Smaller sensors make wide-angle lenses less effective, but you canincreasethecoveragebytiling.

Panoramaheads

Panoramaheads

Numerous QuickTime tripod heads are available, designed to assist in takingimagesattheexactanglesneededtobuildupaQuickTimeVRscene.Theseareessentially360ºpanoramas,whichinsomecasesalsoallowtheviewer to lookupanddown(hencethesecondadjustmentontheManfrottohead).Inordertocreate panoramas, each shot should be taken from exactly the same spot.QuickTimeVRtechnologyincludesspecializedstitchingsoftware.

ReallyRightStuff

ManfrottoQTVRhead

KaidanQuickPanIIIrotatorbase

Apanoramasequence

Step 1Decide on the area of the scene youwant to cover, and the lens focallength you will use. Longer focal lengths need more frames to complete thesamecoverageasawide-anglefocallength:thisgivesabiggerfinalimagefile(good for a high-resolution image, but it takes upmore space on thememorycardandharddrive,andismoredemandingoftheprocessing)andlessangulardistortion.

Step 2Mount the camera on the tripod and level the head.Use aQuickTimehead,orequivalent,mounting thecameraso that thenodalpointof the lens isexactly over the axis of rotation. If the scene is distant and you are using atelephoto, takecare to lineupframes.Shootingwith thecameraframeverticalgivesadeeperpanorama.

Step3Makeadryrun.Inthesimplestcase,pickashortpanorama,loosenthetripod’spanhead,startattheleft(orright),andcheckthenumberofframesthatyou will need, panning to one side, allowing for an overlap of about 30%(between15%and40%).Judgetherotationbetweenframeseitherbyusingthescaleonthepanhead(ifthereisone),orbyeyethroughtheviewfinder.Ifyouhaveagridfocusingscreen,useoneoftheverticallinesasaguide.Findadetailinthescenethatiseithercenteredorontheleadingedgeoftheframe,andpanthecamerasothatitappearsonthisgridline(seebelow).

Step4Selectfixedsettingsfortheexposureandwhitebalance.Checktheseoutfor sample frames across the sequence, paying particular attention to thehighlightclippingandhistogram.Youmayhave tosacrificesomehighlightorshadowdetail.

Step 5 Check for movement within the scene, such as a passer-by, objects

movinginabreeze,orchanginglight,andtrytoshootwhenthereisnone.Shootthesequence.

Step6Checkthatyouhavealltheframes.Missingaframeinasequenceiseasywhenyouaretilingratherthandoingasimpleside-to-sidepanorama.

Threeimages,shownhereinred,blue,andgreen,wereusedtocreatethis

panoramaofPrague.

CreatingHDRImages

Highdynamicrangeimaging,orHDRI,isarelativelynewwayofcapturingthe

entirerangeoftonesinahigh-contrastscene,fromshadowstohighlights,whichisbeyondtheabilityofanormalsensortocapturewithoneshot.

For instance, a typically bright, sunlit scene containing highlights and

shadowshasadynamicrangeintheorderof2,500:1,andwhilethehumaneyecan accommodate this (though it does it by scanning the scene rapidly andbuildingupacumulativeimage),adigitalsensorcannotcompletelymanageit.This isbecause,whilea typical12-bit sensorshootingRaw theoreticallyhasadynamicrangeof4,000:1,itspracticalrangeiscloserto1,000:1,mainlybecauseof noise. If the sun appears in the shot, the dynamic range will shoot up tosomethingintheorderof50,000:1.Anothertypicalhighdynamicrangesceneisaninteriorwithaviewtoasunlitexterior—asituationwherethedynamicrangecanreach100,000:1.

HDRprocessing

WhenprocessinganHDRimage,it’spossibletousesettingvaluesthatcreatean

artificial-lookingresult.

Ifthecameraremainssteady,asequenceofframesatdifferentexposurescan

capture all the detail. The software exists to combine such a sequence into asingleHDRfile format.ThereareseveralHDRformats,but typically theyare32bitsper channel, and insteadof this extrabitdepthbeingpre-assigned toarange of values, as happenswith 8-bit and 16-bit images, it is used in quite adifferentway. The bits are assigned to decimal points, so that any real-worldtonal value can be given a precise digital value, and for that reason, this isknown as floating point coding. A number of commercial programs exist forgenerating an HDR 32-bit floating point image file automatically from asequence of exposures (normally shot about 2 ƒ-stops apart). They includePhotoshop,Photomatix,andeasyHDRPro.

The resulting HDR image contains all the information, but is essentially

unviewableduetothelimitationsofthedisplaymedia.Mostmonitorshaveabitdepth of 8 and can at best handle a dynamic range of about 350:1,while fewpapers do better than about 100:1. This requires a second step, which is tocompressthedatainthe32-bitimagedownto8bitsperchannel.

ThisiswhereHDRIbecomestricky,becausethereisinprinciplenoidealway

todothis.Somethinghastogo,andasatisfactoryresultdependsonthewaythetonesweredistributedintheoriginalscene,ontherangeofexposurestakeninorder to create the HDR image, the algorithms and techniques used forcompressing,andontopofallthisthetasteandjudgementofthepersondoingit. The net result is deep unpredictability and many different appearances ofoutput.

Theprocessofassigningtheoriginalhugerangeofvaluesfromdeepshadow

to bright highlight is known as tone-mapping, for obvious reasons, but the

methodsvaryaccordingtothesoftware.Photoshopoffersfourroutes:Exposureand Gamma, Highlight Compression, Equalize Histogram, and LocalAdaptation, of which only the last offers a useful “photographic” result.Photomatix, the leading dedicated HDR software, offers the choice of ToneCompressor (which features the powerful ToneMapping control) and DetailsEnhancer.The former is the route for themore“artistic”HDR imagery,whilethelattercreatesmorenaturalisticresults.

Tone mapping an HDR image is unpredictable and often difficult to get

exactly as you would like. Nevertheless, HDRI is hugely powerful and canenablephotographyofakindthatwaspreviouslyimpossiblewithoutthehelpoflighting, and makes high-quality, professional-looking existing-lightphotographyperfectlyviable.

Fulltonalrange

Createdfromasequenceofthreeexposuresbeginningwith1secondatƒ/32,whichrevealsalltheshadowdetail,andendingwitha1/125secondshot,whichholdsthebrightesttones.Thesemergetorevealdetailinboththeshadowareas

whileholdingthehighlightsaroundthewindows.

CreatinganHDRimage

Although you can create an HDR image using Photoshop’sMerge to HDR...commandunderFile>Automate, themorepopular route is tousePhotomatixPro, a dedicated HDR program. Photomatix Pro is available either as astandalone application or a Photoshop plug-in, providing a greater degree ofcontrol and allowingyou to be a littlemore “artistic”with theToneMappingsettings.

+2EV,0EV,–2EV

1TocreateanHDRimageyouneedtostartwithanumberof

exposuresofthesamescene;threeisusuallysufficient.What’simportantisthat,betweenthem,theexposurescapturethefullrangeoftonesinthescene,fromthebrightesthighlightstothedarkestshadows.AllDSLRsallowyoutobracketexposures,andwiththecamerasettoContinuousshooting,it’seasytocapturethevariousexposuresyou

need.Alternatively,Photomatixwillallowyoucreate“faux”HDRimagesusingjustoneRawcapture.AlthoughthiswillnotcreateanHDRimageinthestrictsenseoftheterm,you’llbeabletousetheToneMappingsettingstocreateHDR-likeimages.

2OpenPhotomatixandclickGenerateHDR.Navigatetothe

exposuresandclickOK.

3OncePhotomatixhasprocessedthevariousexposures,select

ToneMapping;thisiswhenyou’llbegintoseehowyourimagewilllook.ThemostimportantsettingsareLightSmoothingandMicro-Smoothing.Experimentwiththesetodeterminehownaturalisticyouwantyourimagetoappear.

4Inthisfinalversion,LightSmoothingandMicro-Smoothing

settingsweredeliberatelychosentocreateapainterlyeffect.The16-bitHDRimagewassaved,andfurthercolorandtoneworkwasundertakeninPhotoshopbeforetheimagewassharpenedslightlyandsavedasan8-bitTIFF.

THE D IGITAL ENVIRONMENT PART IV

TheZoneSystem

The Zone System was developed by the famous 20th-century Americanlandscapephotographer,AnselAdams,asawayofobtainingtheoptimumtonalrange in ablack-and-whiteprint.The systemcombinesbothmeasurement andjudgment—inotherwords,itamalgamatestechnologyandopinion.

Still highly regarded by some traditional photographers as the meticulous

craftsman’s approach to considered, unhurried photography, it lostmost of itspurposewhencolor tookoverfromblack-and-white—particularly transparencyfilm,whichallowslittletobedonewithitafterexposure.Digitalphotography,however,returnsimagecontrol tophotographers,andtheoldZoneSystemhassomevaluable lessons to teach in thenewcontext.Of course, it is at itsmostusefulinshootingsituationsthatallowtimeforreconsideration—landscapeandarchitecture, for example, rather than reportage. However, in digital capture,providingthatyouareshootinginRawformat,youhavethetimetoreconsidertheimagelaterandalterthetonalrelationships.Thisassumes,ofcourse,thatinshootingyouhavenotblownoutthehighlightsorlosttheshadows.

Identifyingzones

Thisisanexampleofdividinganimageintomeaningfulzones.Onlyreasonablysizedareasareworthdesignating,asverysmallareasareunlikelytoinfluence

yourexposurechoices.However,thisisnotanexactprocedure.Inthisarchitecturalshotofaporticoinquitebrightsunlight,therearesixobviously

separatedtonalblocksorzones.

Numberofzones

Although Ansel Adams’ original scale has ten zones, as shown here, some

photographerswho follow the systemusenineor eleven zones.The argumentfortenisthatitfollowstheoriginaldescription,butZoneV,midtone,isnotinthecenter.Usinganoddnumberofzones,ZoneViscentraland,with11zonesin particular, the spacing is easy to calculate digitally—an increase of exactly10%foreachstepfromblacktowhite.Ontheotherhand,theresponseofmanycamerasensorsislongerattheshadowendofthescale,whicharguesmorefortheoriginaltenzoneswithZoneVoff-centered.

Visualizingthefinishedimage

Inthesystem,allofthetonalvaluesinasceneareassignedtoasimplescale

of ten, from solid black to purewhite, each one ƒ-stop apart. The key to theprocess is to identifyandplace the important tones into theappropriatezones,and this demands what Adams called “pre-visualization.” This is forwardplanningbyanothername,andmeanstheprocessofthinkingaheadtohowyou

wantthefinalimagetoappear—on-screenand/orinprint.ThegreatvalueoftheZoneSystem, still applicable today, is that it classifies anddescribes the tonalstructure of any image in a commonsense way. Different photographers havedifferent ideas about howan image should look tonally, and theZoneSystemallows for this individuality. AsWhite, Zakia, and Lorenz put it in TheNewZone System Manual, success depends on “how well the print matches thementalpicture,nothowwellitmatchestheoriginalscene.”

BecausetheZoneSystemclassifiestonesintermsofhowtheylookandwhat

weexpectfromthem,itisnotthesameastonalrangeordynamicrange.Instead,itisatoolformakingsurethattheimagehasthetonesyouwantforthepartsofitthatyouconsiderimportant.ThethreemostusefulvaluesareZonesIII,V,andVII.Betweenthemtheycoverthereadablepartsofmostscenesandimages—inotherwords,thefivetexturedzones.

The most important action in the Zone System is called placement. This

happenswhen,havingdecidedonthecriticalareaofthescene,thephotographerassignsittoazone.Astheexamplesonthefollowingpagesillustrate,thiscanmeanchoosinganareaofshadoweddetailandplacingitinZoneIII,oramoreinterpretivechoice.Inallcases,ittheninvolvesexposingaccordingly—orwithRawformat,adjustingtheexposurelater.

Makingazoneruler

Therulershownismadeinmuchthesamewayasthedynamicrangetest,withtheadditionoftexture.Insteadofphotographingablanksurface,shootonewithtexture,suchascloth,unpolishedwood,orsmoothstone.Alternatively,chooseareasfromexistingimagesinyourstocklibrarythatconformtothedescriptionsof thezones.Arrangetheminasteppedscaleandadjust theoverallbrightnessvalues.ThereismoreinformationonmeasuringaveragevaluesofanareaunderExposuremeasurement.

Thezones

ZoneISolid,maximumblack.0,0,0inRGB.Nodetail.

ZoneIIAlmostblack,asindeepshadows.Nodiscernibletexture.

ZoneIIIFirsthintoftextureinashadow.Mysterious,onlyjustvisible.

Zone IV TEXTURED SHADOW. A key zone in many scenes and images.Textureanddetailareclearlyseen,suchasthefoldsandweaveofadarkfabric.

ZoneVTypicalshadowvalue,asindarkfoliage,buildings,landscapes,faces.

ZoneVIMIDTONE.Thepivotalvalue.Average,mid-gray,an18%graycard.Darkskin,lightfoliage.

ZoneVIIAverageCaucasianskin,concreteinovercastlight.

Zone VIII TEXTURED BRIGHTS. Pale skin, light-toned and brightly litconcrete.Yellows,pinks,andotherobviouslylightcolors.

ZoneIXThelasthintoftexture,brightwhite.

ZoneX Solidwhite, 255,255,255 inRGB.Acceptable for specular highlightsonly.

ApplyingtheZoneSystem

TheZoneSystemisjustasrelevanttodayasitwasinthedaysbeforedigitalcapture.Thereasonsforthisaretwofold:easy,accuratemeasurementandtheabilitytoadjustbrightnessandcontrastaftertheevent.Usingitintherun-uptoshooting,aswasoriginallyintended,isevenbetter,butinreal-lifesituations,thismaybeanunattainableluxury.

Tobeginwith, concentrate on the following three important zones:ZoneV

(midtones),ZoneIII(texturedshadow),andZoneVII(texturedbrights).Identifytheminthesceneandthen,ifyouhavethetime,measurethemwiththemeter(camera’sspotorhandheld).

It’s important to understand the differences in dynamic range between the

cameraandthemediaonwhichyouintendtodisplaytheimage.Evenifadigitalcamerahasasmallerdynamicrangethanfilm, it isstill farhigher thanthatof

any paper. Basically, from the original scene through digital capture to finalprint,therangebecomessmaller.

Placementinpractice

In this dramatic architectural image, the detail in the foreground shadow areawasfelttobeessentialtotheoverallcomposition,andsowasplacedinZoneIII.It was also important to retain detail in thewell-lit areas in the center of theimage,thoughwithadegreeofchoice:iftheyweretobeonlyjustvisible,theycouldbe inZoneVIII, but tobedefinite, theywouldhave tobe inZoneVII.SettlingforZoneVIIputtherestoftheimageintocontext.Therewouldneedtobe a five-stop difference between these two areas to give the overall imagesuitablecontrast,sotheforegroundareawasplacedinZoneIIandtheexposuresetaccordinglyforthefinalresult.

Originalexposure

FirstattemptataZonemapfortheoriginalexposure.

Finalexposureastopbelow

FinalZonemapforexposureastopbelow.

High-dynamicrangescenes

Whenconfrontedwithascene inwhich thedynamicrangeexceeds thatof thecapacityof the camera, theZoneSystemapproach is to identify the importantzoneandexpose for that. Indeed it isaverypracticalwayof thinking throughthesesituations.Inpractice,therearethreepossibleoptions:

1Exposefortexturedbrights(ZoneVII),andacceptlossofshadowdetail.

2Exposefor themidtones(ZoneV),andsplit the lossof textureatbothends:shadowandhighlight.

3 Expose for textured shadow (Zone III), and let the brighter tones go tofeaturelesswhite.Visuallythisisusuallytheleastacceptableoption.

...exposeforbrights

...exposeformidtones

...exposeforshadows

CommonLightingScenarios

Almostallscenesthatyouphotographcanfitintooneofseveraldistincttypesoflighting situation. The three main divisions (the three technically mostimportant) are based on contrast, and are Average, Low Contrast, and HighContrast.Ofthese,theonelikelytocausethemostproblemsisHighContrast.

This is particularly so in digital capture, partly because highlights aremore

easilyblownoutdigitallythanwithfilm,andpartlybecauselow-contrastimagesaresimpletoadjust.

Whatmakesuptheselightingsituationsisacombinationof thelight(bright

sun,spotlight,overcast,andsoon),thesubject(itscolor,brightness,shininess),and how you identify the subject. This last point is critical. What onephotographer identifiesas important in the framemaywellnotbe thesameasthatchosenbysomeoneelse.“Subject”doesn’tnecessarilymean“object,”but

mightinsteadbeapatchoflightoranareaofshadow.Thus,youmighthaveascene thatmeasures average for exposure, but the key tones are in the brightareas—say, the texture of some prominent clouds in a landscape. There areendless sub-divisions possible, but the more there are, the less useful theybecome.

Averagecontrast

Whenpresentedwithanaveragelevelofcontrast,itshouldbenoproblemto

selectthecorrectexposure,bearinginmindalltheusualcaveatsaboutavoidingblowinghighlightsasopposedtoshadowdetail.

Equalspreadoftones

Keytonesdark

Keytonesbright

Keytonesaverage

Highcontrast

Wherethereisalotofcontrast,itisespeciallyimportanttoidentifythesubjectandkey tones, asoften somethinghas togiveway.Sacrificedetail in the lessimportantareasofyourimage.

Lowcontrast

Insituationslikethis,itisimportanttodecideifcontrastshouldstaylow,givenhoweasyitistoincreasecontrastbysettingblackandwhitepoints.

Noise

Numerouscomparisonshavebeenmadebetweennoiseandgrain,andinasensethisisunderstandablebecauseoftherelationshipbetweensensitivity/filmspeedandtheamountofnoise.

However,therethesimilaritiesend,asnotonlyarethecausesdifferent,butso

arethetreatments.Indeed,theonegoodthingaboutnoiseindigitalphotographsis that it can be dealtwith.Not perfectly andnot easily, but there are varioussolutions.

Inordertotreatnoise,wehavetodefineit,andthisisn'tassimpleasitmightseem. Technically, noise is artifacts or errors introduced into the image byelectrostaticcharge,andthescientificapproachtoitrevolvesaroundthesignal-to-noise ratio. However, this does not take into account the very importantperceptual component. After all, at the pixel level, noise and detail areindistinguishable. In otherwords, it is largely the eye andmind of the viewerthat distinguishes between subject detail (wanted) and noise (unwanted).As aparallel,anyretoucherwhohasworkedonscannedfilmimagesknowsthatwithsome subjects, such as an unswept floor or a rocky landscape, it may beimpossibletodecidewhataredustspecksandwhatistexture.

Noise is detail, but unwanted detail. This immediately creates a problem,

because the definitionof “unwanted” is completely subjective.This hasmajorimplications when it comes to treating a noisy image, and it also means thatthere are two distinct stages in digital photography at which noise can besuppressed.One is at capture, theotherduring image-editing.Noise isheavilydependentonanumberofvariables,andsocanvaryfromshottoshotaccordingto the camera settings and the conditions. You can expect to encounter noisewith long exposures, high sensitivity, high temperatures, and in images withlarge, smooth shadow areas, but it is difficult and time-consuming to checkwhileshooting.Asmuchaspossibleiscontrolledbythecamera’sprocessor,andthisvariesaccordingtothemakebecauseitdependsonthealgorithmsusedandon the processing techniques chosen by manufacturers. Most camera menusofferthechoiceofnoisereduction.

Variationsofnoise

Photonnoise

Thisisnoisecausedbythewayinwhichlightfallsonthesensor.Becauseoftherandom nature of light photons and sensor electrons, it is inevitable with alldigitalimages.Itappearsasdark,bright,orcoloredspecks,andismostapparent

inplainmidtonedareas,leastapparentinhighlights.

Readoutnoise(orampnoise,orbiasnoise)

Thisisnoisecausedbythewayinwhichthesensorreactsandthewayinwhichthe signal is processed by the camera. Similar to electronic noise in recordedmusic,thisisgeneratedbytheprocessoritself,andthemoreitisamplified,themoreprominent itbecomes.Thus, increasingtheISOsettingbyturninguptheamplifiercreatesmorenoise.Itistosomeextentpredictableandcanbereducedbyin-cameraprocessing.

Randomnoise

Causedbyunpredictablebutinevitabledifferencesintimingandthebehaviorofelectricalcomponents.

Darknoise(alsoknownasfixed-patternnoiseandlong-exposurenoise)

Noise caused by imperfections specific to each individual sensor. Increases inproportiontotheexposuretimeandtotemperatureincrease,butisindependentof the image, so can be reduced by in-camera processing bymeans of “dark-frame subtraction.” This extra process takes as long again as the originalexposure.Coolingalsohelps.

Resetnoise

After each shot, the camera resets the sensor to a zero position, ready for thenextexposure.Multipleclocksintheprocessormaycauseslightdifferencesinthetimingofthis,whichgeneratesnoise.

In-cameranoisereduction

Many cameras have a noise reduction option to deal with long exposures. Itdoublestheprocessingtime,butsavesagreatdealofworklater.Thisin-cameraoption tackles the known pattern of noise that occurswith long exposures bysubtractingthepredictablebehaviorofthesensor.

Theprincipleistomakeasecondexposureforthesameexposuretime,butwithnoimage.Thepatternofnoisewillbethesameasfor theexposedimage,andcanbesubtractedfromthenoisyimagebyanappropriatealgorithm.Youcoulddothisyourselfinimageeditingwithalotofeffort,butitisunnecessaryifyouchoosethenoisereductionoptioninthecamera’smenu–itdoesthesamethingmoreefficiently.

Highnoise

Thisimageexhibitsextremedigitalnoise.Thenoiseiscausedbyonephotositeinthesensorpickingupsignificantlymorelightthanitsneighbors.Asdigitalsensorchipsaretypicallyarrangedinacolorfilterarray,the“rogue”pixels

tendtowardasinglecolor;red,green,orblue.

Theappearanceofnoise

Certain types of noise have a characteristic appearance, as you can see fromtheseenlargedexamples.

Luminancenoise:

Appearsasvariationsinbrightness—abasicallymonochrome,grainypattern.

Chrominancenoise:

Variationsinhueareprominent.

Hotpixels:

“Stuck”pixelsappearasbrightspots—verynoticeableandvisuallydisturbing.

JPEGartifacting:

Blocksofeightpixelsaresometimesdistinguishable—aresultoftheJPEG

compressionprocessing.

WhiteBalance

Oureyesaresogoodatadapting todifferent lightingconditions thatgenerallywe perceive white as white. But the color of light varies, and the two mostimportant ways in which this affects photography are color temperature(between reddish and bluish) and the off-color glow of fluorescent and vapordischargelamps.

Tothehumaneye,whiteisnormal,andanydeviationfromthisappearstinted

—notnecessarilywrong,butnotbalanced.Unlessyouspecificallywantacolorcastforaparticularreason(thewarmglowofasettingsunonsandstonerocks,for instance), it’s normal to strive for lighting that appears white—that is,neutral.

With film cameras, the solution was to use an appropriately balanced film

(either daylight or tungsten) and filters. Digital cameras sidestep this byprocessing the color information according to your choice.With aDSLR youcando thismanually,orchoose fromanumberof standard settings,or let thecamera find the balance automatically. Themanual method (also known as a“custom”whitebalance)involvesaimingthecameraataknownneutralsurface,suchasapieceofwhitepaperorastandardgraycard.Thecamera’sprocessor

then stores this informationandapplies it to subsequent images,making it themostaccuratemethodwhenyouareshootingforaperiodoftimeinasituationwithunchanging light.Thesimpleralternativesareeither tochooseoneof thestandardsettingsinthewhitebalancemenu,ortoselectAutoandletthecameraworkitout.

Automaticwhitebalancerequiresthecamera’sprocessortoanalyzethescene,

identify highlights, and adjust the overall balance, and formost situations is agood choice. Some high-end DSLRs supplement the sensor analysis withseparatethroughthelens(TTL)colormetersandincidentmetersmountedonthecamera.

Thecoloroflight

Theprincipleofcolortemperatureisthatwhenamaterialisheated,itfirstglowsred,thenyellow,increasingtowhiteathighertemperatures(hence“white-hot”),and thenblue.This applies to anyburning light source, including the sun andtungsten lamps, and it gives a way of calculating the color of light by itstemperature(measuredindegreesKelvin,whichissimilartoCelsius/centigradebutstartsatabsolutezero).Forphotography,thenormallimitsbetweenreddishand bluish are from about 2,000K (flames) to 10,000K (deep blue sky). Themiredshiftvaluesareastandardmeasureofthenumericaldifferencesbetweentemperatures.Youwillneed torefer to thesewhenusingcertain image-editingsoftware,suchasPhotoshop’sCameraRawplug-in.

Bracketingwhitebalance

SomeDSLRsofferabracketingoptionthatworksinawaysimilartoexposurebracketing—aburstofseveralconsecutiveframesinwhichthewhitebalanceis

alteredincrementally.

Toptobottom:

Inthisshot,acustomwhitebalancewasset,withalighttemperatureof4,500degreesKelvin.Inthisvariant,thecamera’sautomaticwhitebalancemodewasused.Thisshotwastakenwiththewhitebalancesettothepreset“shade”

option.

Whitebalancesettings

Althoughtheactualdescriptionsvaryfrommaketomake,mostDSLRsofferasimilarrangeofchoices tocovercommonlyencounteredlightingconditionsasshownintheexamplesbelow.Theprecisevaluescanalsobeadjusted.

Settingacustomwhitebalance

This varies in practical details according to themake of camera, butwhat allhaveincommonisthemeasurementofareliablyneutraltarget.Whitepaperorcardwill do, but for greater accuracy consider carrying a standard gray card.Thisisatypicalsequenceofsteps.

1SelecttheWhiteBalanceoptionfromtheShootingmenu.

2IntheWhiteBalancemenu,scrolldowntotheCustomorManualoption(here

it’scalledPreset).

3Photographaneutraltargetthatislargeenoughor-closeenoughtofillthe

targetarea,inthiscasealargeexpanseofwhitewall.

4Waitforconfirmationthatthiswassuccessful,orrepeatifoverexposed,underexposed,oroutofcompensationrange(warningmessageindisplay).

ConfirmthesettingbyselectingOK.

5ChoosePresetfromtheWhiteBalancemenutousethissetting.

ManagingColor

Getting accurate color has always been an issuewith photography, and nevermore so with digital photography. In a way this may seem a little strange,because film photographywas just as affected by color temperature and othercolordifferencesinlighting.

Withdigitalphotography,however,itcanbemanaged,andsomustbe.There

are twosides tocolormanagement.One is linkingthedifferentways inwhichthevariousdevicesintheworkflowreproducecolor,fromcameratomonitortoprinter.Theotherisstayingfaithfultothecolorsofthesubject.

First,color-managingthedevices.Thisinvolvesalloftheequipment,notjust

thecamera.Ultimately, itdependsonadescriptionofhowadevice readsandrenders colors. These descriptions, which can be read by other machines,conform to thestandardsof the InternationalColorConsortium(ICC),andareknownasprofiles.Everypieceofequipmentintheworkflowshouldhaveone,includingthecamera.

Basically, the ICC profile rules, but fine-tuning it is the key to absolute

accuracy.Normally,agenericprofileof thecameraisautomaticallyembeddedin the image file, andmajor software applications like Photoshop can read it(withthehelpofadditionalupdates).

But device performance is not always consistent, and it can driftwith time.

Keeping the profile up-to-date is the answer. In principle, for a camera thismeanscheckinghowitcopeswithastandardcolor targetandalteringtheICCprofileaccordingly. Inpractice, this involvesprofile-buildingsoftware thatcancompare an image with stored information. You shoot a target such as theGretagMacbethColorCheckerunderknownlightingconditions,andthesoftwaredoestherest.Seethefollowingpagesforsettingupthisprocedure.

Selectingcolorspace

Somewhereinthecamera’smenuistheoptiontoselectthecolorspace,which

maybecalledsomethingelse,suchascolormode.AtypicalchoiceisbetweenAdobeRGB and sRGB. Formost serious use, selectAdobeRGB.This has awider gamut,whichmeans that the camerawill capturemore colors from thescene.

ColorandtheRawformat

ShootinRawformatandtheprecisewhitebalancesettingsdonotmatter.Thisisbecause the Raw format bypasses the processing that normally applies thesesettings in camera.All the data is kept separate in Raw format, including thewhitebalancesettings,whichcanbeadjustedinimage-editing.

Usingastandardtarget

Calibrationisalsoaffectedbythesubjectsandscenesthatyouphotograph—

theymaydifferwildly in theway theyare lit, and this is thesecondaspectofcolormanagement.Theeyeaccommodatessowelltodifferentcolorcaststhatitmaynotbeagreathelp.Underskylightfromaclearbluesky,itreadswhatyouthinkshouldbewhiteaswhite,eventhoughitactually isadefiniteblue.Withfilm, even though a slidemight have had a color cast, at least the imagewaslockedintothephysicaltransparency,andcouldbeidentified.Withdigital,onlythe photographer is in a position to saywhat the colors should be and, if youcan’tremember,nooneelseisinapositiontosay.Settingthewhitebalancetoone of the presets, such asCloudy or Shade, gets you close, as does a visualcheckoftheLCDscreenaftershooting,buttheonlywaytoguaranteethecolorsistomakeatestshotwithastandardtarget—anyofthesametargetsneededfordevicecalibration.Ifyoudothisjustonceforanygivenlightingsituation,youhave themeans toadjust thecolorsaccurately in image-editing.Dependingonthecamera,theremayalsobeaseparatehueadjustmentcontrol,allowingyoutoshifthuesaroundthespectruminawaysimilartotheHuesliderinPhotoshop.Typically,theadjustmentsaremeasuredindegrees.

THE D IGITAL ENVIRONMENT PART V

ColorTargetsforConsistentColor

Ifgettingcoloraccurateisessential–tomatchthecolorsinacompanylogo,forexample–thenuseastandardcolortarget.

Fornormalphotography,thetwomostvaluablearetheKodakGrayCardand

the GretagMacbeth ColorChecker shown here. Their colors are knownquantities,andsotheycanbeusedtojudgeandcorrectyourcapturedcolors.Atthevery leastyoucanuse themforvisual reference,but theColorCheckerhasthe more valuable function of helping to create ICC camera profiles. Underhighlycontrolledconditions,suchasfixedstudiolightingset-ups,somelightingmanufacturersrecommendusinganIT8.7/2target,whichisnormallyusedforscanning.

GretagMacbethColorChecker

Based on the Munsell System (the source of the hue, saturation, brightnessmodel),this24-patchmosaicofveryaccuratelyprintedcolorsisthecolorchartof choice for photography. Not only is it a known industry standard, but itcontains “real-life” colors such as flesh tones and the complex greens ofvegetation.Importantly,thecolorsreflectlightthesamewayinallpartsofthevisible spectrum,meaning that they are consistent, whatever the lighting, andtheyareprintedmattetoavoidreflectionsthatwouldupsetthereadings.

The top row containsmemory colors that include skin tones, blue sky, and

foliage, the second row medium-saturated colors, the third row the threeprimaries and secondaries, and the bottom row a gray scale from “white” to

“black.”Note,however,thatthedynamicrangeofmatteprintedcolorsismuchlessthananyoftheothercolordisplaysyouarelikelytocomeacross,andthe“black”isreallyadarkgray.

To preserve the color accuracy of the target, avoid fingerprints, high

temperatures and high humidity, expose it to light only when using it, andreplaceitabouteveryfouryearsinanycase.

GretagMacbethColorChecker

TheclassicGretagMacbethColorCheckerhasapplicationsingraphicdesign,television,andpublishingaswellasphotography.Its24coloredinksare

preparedaccuratelyinthelab.

GretagMacbethColorCheckerDC

This is the newer, more sophisticated version of the basic 24-patch

ColorChecker, designed specifically for digital cameras, and extremelyexpensive. It could be considered overkill for most photography, as while itcovers a wider range of colors, it demands more precision in setting up forprofiling. The central white patch is larger than the others to facilitate white-balancepresets.A strip of glossyprimaries and secondaries is controversial—they are intended to increase the range of “knowable” colors but demand anabsoluteavoidanceofanyreflections.Somecameraprofilingsoftware,suchasinCamera,hasanoptiontoautomaticallyignorethesepatches.

GretagMacbethColorCheckerDC

TheColorCheckerDCfeatures177colorsacross237squares.Itis8.5x14in

(22x35cm)andisspecificallydesignedtomeettheneedsofdigitalphotography.ItcanbeusedwithprofilingsoftwaretocreateanICCcameraprofile.Thelargewhitesquareinthecenterisdesignedtoassistdigital

photographersinsettingtheirwhitebalance.

KodakColorControlPatchesandGrayScale

LessusefulthantheColorCheckerforphotography,butbetterthannothing,thissetoftwosmallstripshastraditionallybeenusedasacolorreferencebyreprohousesandprinters.Thestripsareconvenientlysizedforplacingnexttostill-lifesubjects and paintings, and are an approximate guide for printing. The GrayScalehas20stepsin0.10densityincrementsbetweenanominal“white”of0.0densityandapracticalprinting“black”of1.90density.ThelettersA,M,andBrepresent reflection densities of 0.0, 0.70, and 1.60 respectively. The ColorControl Patches are based onweb offset printing inks similar toAAAA/MPAstandard color references, and include the three primaries, three secondaries,plusbrown,white,andblack.

Usingacolorchartorgraycard

1Placeorhaveamodelholdthechartfull-facetothecamera.

2Makesurethelightingisevenacrossthechartandavoidreflections.

3UsealowISOsensitivityandmeterasaverage.

4 For profile building, follow the software instructions (normally includesturning off automatic camera settings and using either daylight or electronicflash).

5Evaluateinimage-editing

DigitalColorCheckersemigloss

LiketheColorCheckerDC,theDigitalColorCheckerSemiGlossisdesignedfor

real-lifesituations.Its140patchesincludecolorsdesignedtoreflectskin,foliage,andbluesky,inadditiontoGretagMacbeth’sstandardcolors,

GrayCard

The 18% reflectance Gray Card has long been a reference tool in black-and-white photography, being a standard mid-tone. In a digital image, it shouldmeasure50%brightnessandR128,G128,B128.Thereasonfor18%asamid-tone is the non-linear response of the human eye to brightness. It ismatte toavoidreflections,andhasareflectiondensityof0.70,whichitmaintainsacrossthevisiblespectrum.

CreatingaCameraProfile

Forthevastmajorityofus,creatingaspecificcolorprofileforthecameraisnotnecessary—we’re unlikely to notice any minor color discrepancy, and on therareoccasionwhencolorreallyhasgoneawry,it’susuallyrelativelyeasytofixinpost-production.

However,cameraprofilescanbeusefulwhenaphotographerworksregularly

in a repeatable kind of lighting.A studiowith photographic lights is themostobvious example. Personally, I do quite a lot of location shooting in lowsunlight,andsofinditusefultohaveaprofilejustforthis.Theprofileisasmalltextfile,readablebythecomputer,thatdescribestheexactwayinwhichanyofthesedevicesdisplayscolors.Aseverythingbeginswiththedigitalcapture,thecameraprofileoccupiesthefirstplaceinthechainofevents.

DSLRsnormallyhavedefaultprofiles,alsoknownas“canned”profiles,built

in to their systems and attached to the image files they create. Photoshop, forinstance, will read the attached profile automatically. So far so good, but thecannedprofilemayonlybeanapproximationforanindividualcameraworkinginspecificlightingconditions.If,likemostphotographers,youbeginbyrelyingon this default profiling—in other words, doing nothing—you may come torecognize certain peculiarities. One of the traits of my current DSLR, for

example,isapinkcasttolighttonesinsunlight.Thiskindoftraitiscorrectableinimage-editing,butabettersolutionistocreateanexactprofileforthecamerawhen shooting in these conditions. The profile, in effect, compensates for thecamera’scolormisbehavior.

Twoimportantwordsofwarning,however.Oneisthatcameraprofilesmust

bespecifictobeofanyuse—specifictoonecameraandtothekindoflighting.Theotheristhattotalaccuracyisrarelynecessary,andunlessyouhaveanexactneed, such as in the copyingofpaintingsor the reproductionof a commercialproduct’sbrandcolors,youmaywellbewastingyourtimefrettingoverminutedifferencesincolorvalues.

TheGretagMacbethColorCheckerinuseonlocation.

Studioprofile

AnIT8targetistypicallyshotinstudioconditions,oncethelightinghasbeen

adjustedforthesubject.

Careofyourtarget

Colortargetsareexpensiveanddelicateitems,sotakethefollowingprecautions:

• Handlethemcarefullytoavoidkinksandscratches.

• Removeanyprotectionsleevebeforeuse.

• Returnthetargettoitsprotectivewrappingimmediatelyafteruse.

• Keepoutofstronglight,particularlysunlight,becauseofitshighUVcontent.

• Storeinacool,dry,anddarkplace,preferablybelow70ºF(21ºC)andbelow50%RH.Avoidsuddentemperaturechangesthatmightcausecondensation.

• Useadry, lint-freecloth toclean thesurface,anddonotusealcoholoranyothercleaningfluid.

Thecolorsofthetargetwillchangewithtime.Ideally,replacethetargeteverycoupleofyears.

IT8target

TheIT8targetisastandardpattern,with19columnsof13colors,withthreeadditionalcolumns(20-22)whichare“vendorindependent,”inthatdifferentmanufacturerscanplacetheirowncolorsthere.Italsofeaturesa24shade

grayscalealongthebottom.

Photographthecolortarget

1Placethetargetsothatitisevenlylitandintheilluminationthatyouexpecttouse.Ifthelightsourceisconcentrated,suchasthesunoraflash,makesurethatthetargetisangledtothelighttoavoidreflections.

2Makesurethatallthecamerasettingsareataverageorneutral—forinstance,nohueadjustments.Selecteithertheappropriatewhitebalancechoiceor,betterstill,createacustomwhitebalancebyreferencingeitherawhiteorgraypatch(oralargerGrayCard).

3Ifyoucanadjustthecapturethroughthecameraexposurecontrolorlighting,aimforagrayscalerangethatisfullbutnottotal.Rememberthatthe“black”onaColorCheckerisbynomeanszero,butadarkgrayinstead.InCameraprofilingsoftware recommends the values shown below. Note in particular how muchlighterat52 theblack is than“pure”0black.Youcan fine-tune thisexposurelaterinimage-editing.

4AnaddedsophisticationrecommendedbyinCameraistoconstructandincludealighttrap—ablackboxwithasmallaperture.Thiswillbeclosetototalblack,butisprobablyoverkill.

5Setupthecameraperpendiculartothetargettoavoidperspectivedistortion.

Alighttrapisabox,paintedentirelywithlight-absorbingblackontheinsideandwithasmallholecutinit.Theblackseenthroughtheholewillhaveno

reflections,andbeclosetototalblack.

Recommendedgrayscalevalues.

CreatetheProfile

Onceyou’vephotographedthetarget,thenextstepistocreateaprofile.Forthisyouwillneedcamera-profilingsoftware.

Eachfollowsitsownprocedure,buttheexamplehereistheinCameraplug-in

forPhotoshop.Youwillneedtoshootandcreateprofilesforeachmajortypeoflightingthatyouexpecttouse—andforeachcamera.

1Ensurethatnocolorprofilesareattachedtotheimageby

checkingallthepossibleopeningwarningsintheColorManagementPoliciessectionoftheColorSettingsdialog.

2Opentheimage.Ifthewarningdialogreads“Embedded

ProfileMismatch,”choose“Discardtheembeddedprofile(don’tcolormanage).”Ifthewarningdialogreads“MissingProfile,”choose“Leaveasis(don’tcolormanage).”

3Checkthatthegrayscalevaluesareasrecommended.Adjust

Levelsand/orCurvestobringthemintoline.Ifthereisastrongcolorbias,thentheRGBvalueswillbequitedifferent,inwhichcaseconverttoLabandaimforthefollowing:WhitepointRGB243=Lightness96andBlack

Point52=Lightness20.

4Launchtheprofile-buildingsoftware,inthiscaseaplug-in

undertheFiltermenu:Filter>Pictographics>InCamera.

5Choosetheappropriatetarget,anditsreferencefile.

6Alignthegridbydraggingthecorners.Thisalsocompensates

incaseyoushotthetargetatanangle.

7Givetheprofileanamethatyoucanlateridentify,e.g.

“studioflash_raw.icc.”Notethatthestandardsuffixesareiccand.icm.Thesoftwaremayappendtheseautomatically.

8Savetheprofileintheappropriatefolder.Thisvaries

accordingtoplatform(WindowsorMac),operatingsystem,andPhotoshopversion.Thesoftwarewillusually

suggestthedefaultlocation.

Namingtheprofile

In addition to the name, there is also a ProfileDescriptionTag (a descriptionfoundinsidetheprofilefile)usedbysomeapplicationstodisplayitasachoice.If you decide to rename a profile, these applications will not recognize thechangeunlessyouuseautilitytoaltertheTagaswell.Apple’sProfileRenamerdoesthis.Ifyouoverwriteanexistingprofile(whichyoumightwanttodoif,forinstance,youmadeamistakethefirsttime),Photoshopmayneedtoberestartedbeforeitrecognizesthechange.

One-offprofiles

Ifthelightingconditionsforasingleshotareunusual,considermakingaprofilefor that shot alone. Simply shoot the target as part of the take andmake theprofileasdescribedhere—butuseitonlyforthatshot.p

ProfilesandRawconflict

Inprinciple,doNOTusebothRawediting toolsandacustomcameraprofile.When Photoshop CS opens a Raw file, it does so without asking for profileassignment, and then offers an impressive choice of color adjustment tools. Ifyoumakeuseof these,andthen,once the imageisopen,assignaprofile,youcanexpectstrangeresults.Consistencyisthekey.Tobeginwith,createtheRawprofilebymakingnoadjustmentsatall—justthedefaultsettings—andthendothe same when opening all subsequent images. If you vary this by tweakingimages in the Raw editor before applying the profile, remember that you areaddinganextralevelofjudgmenttoastandardprocedure.TrytolimittheRawediting to making sure that neither highlights or shadows are clipped. Thealternative is to abandon the profiling andwork solely in theRaw editor. Formostphotography,outsidecontrolledconditions,thisusuallyworksbestandit’swhatInormallydo.

Memory

Justasdigitalcamerashavedevelopedenormouslyin thelast tenyears,sotoohave the storage devices on which images are temporarily stored—namelymemorycards.

ThetwomajorcardformatsareCompactFlash(CF)andSecureDigital(SD),

withSony’sproprietaryMemoryStickaminor third fora selectionof itsown(primarilypoint-and-shoot)cameras.

Cost isaconsideration,as thehigh-capacitycardscanbeexpensive,andthe

cost per megabyte is much more than it is for desktop or laptop computermemory. In other words, memory cards are for shooting, NOT long-termstorage. Calculate yourmemory card needs by estimating your typical rate ofshooting and the file format.With a largemegapixel sensor, there is amajordifferencebetweenJPEGandRaw,forinstance.

Memorycardsofwhatevercapacityareonlytemporarystorage,andyouwill

needtotransfertheimagesfromthematregularintervals.Howoftendependsonthecapacityofeachcard,whichvariesenormously,from128MBto32GB.Forexample,a128MBmemorycardwilltakeabout50JPEGimagesshotatnormalcompression on a 10-megapixel camera, but only about 15 in Raw formatcompressed. A 32 GB card can store more than 240 times this amount.Consideredasdigitalstorage,memorycardsare,relatively,moreexpensivethancomputerharddrives and imagebanks,butyoumaybewilling topay for theconvenienceofbeingabletocontinueshootingforlongperiodswithoutneedingto download.A4GBcard, for example, has almost the capacity of a standardDVD.Anotherconsideration,however, is thesafetyofhavingsomanyimageswithoutbackupinthecamera.

Alsoconsiderwriteandreadspeedswhenchoosingmemorycards.Theseare

partlyinfluencedbythecameraprocessorandtheformatinwhichyouchoosetoshoot (compression adds time), but also by the make of card—the bestincorporate write acceleration. A good speed currently is in the region of20MB/second.High-endmanufacturerssuchasLexarproducea“professional”rangethatisdesignedtotightenqualitycontrols—inmuchthesamewayasprofilmusedtodifferfromregular—andhasahigherwritespeedthannormal.

CompactFlash

As far asDSLRsgo,CompactFlash is currently themostwidely used type ofmemory card.Using flashmemory technology,CompactFlash (CF) cardsgivenon-volatilestorageandcanretaindatawithoutbatterypower,anddothisinamuch smaller size than normal flash cards, with 50-pin connections. Theymeasure43×36mmandcomeintwotypeswithdifferentthicknesses—TypeI(CF-I) is 3.3mm, Type II (CF-II) 5mm. DSLRs will accept both. Typicalcapacities are 1GB, 2GB, 4MB, 8GB, 16GB, and 32GB–a vast improvementconsidering thatmaximumcapacity in2001was512MB.CFcardsare sturdy,have a long usage life (around 100 years), and operating temperatures from-13ºF to +185ºF (-25ºC to +85ºC). They are PCMCIA-compatible, so easy toreadfromlaptopPCcardslots.

Cardprotection

Therearenumerousproductsonthemarketforprotectingyourmemorycards—investinatleastone.Losingafilmcanbeatragedy,losingamemorycard

containingasetofdigitalimagesisalossofboththeimagesthemselvesandofthemeanstorecordmore.Ifnothingelse,you’reprotectinganexpensive

investment.

SDandSDHC

TheSLRmarketislessdrivenbyminiaturizationthanthat

forcompactcamerasandmobilephones,but thesizeof thatmarketplacehasabroaderimpact.Themostsuccessfuloftheconsumerformats isSecureDigital,whichhasrecentlybeenupdated to support up to 32GB (SD 2.0 or SDHC), thougholdercamerasandcardreadersarelimitedto2GBand,muchlike sofware versions on computers, will not recognize thenewcards.ThesecardsareincreasinglywidelysupportedbyDSLRmanufacturers,aswellasdevicemanufacturers(so,forexample,manycomputersandevenDVDplayerscanreadthem).

MemoryStick

Launchedin1999,Sony’sMemoryStickwasdesignedfor the company’s own digital cameras andcamcorders. It uses a form of flashmemory andwasshapedabitlikeastickofchewinggum,witha10-pinconnector.Newer variants—themost commonofwhich is thePRODuo—areshorterandsmaller.

Memoryrequirements

Inprinciple,youneed sufficientmemorycardcapacity to continue shooting

untiltheimagescanbedownloadedtoacomputerharddriveorportablestoragedevice.Thisdependsonthefollowing:

1Imagefilesize,takingintoaccountwhetheryouareusingcompressionornot.

2Rateofshootingandnumberofshotslikelyinasession.

3Whetherornotyouoranassistantcanbegindownloadingwhileyouarestillshooting.

4Whetheryouarepreparedtodeleteimagesfromcardsbeforeyouhavemadeabackup.

5 Cost: memory cards are more expensive per megabyte than computer harddrives.

Cardreaders

Althoughthecameracanitselfbeconnecteddirectlytoacomputertodownloadimages,itisusuallymoreconvenienttouseacardreader.Downloadingspeed

dependsonthebus,withUSB2andFirewirethefastest.

AWirelessOption

Recent innovations in digital photography include the option of transmittingimagedatawirelessly,whereawirelesstransmitterisattachedtothecameraforimmediateimagetransfer.

FirstintroducedbyNikonforitsD2H,thisisanextremelyvaluableoptionfor

any photographer who needs to deliver images quickly without leaving theshootinglocation.Sportseventsaretheclassicsituation.

Wi-Fi,which stands forWirelessFidelity, is themostwidely used standard

forwirelessnetworking,andisalsoknownas802.11n(othercommonversionsare802.11a/band802.11g). It is relativelyfast (abandwidthof11MB/second,whichtranslatestotransmissionspeedsof1to2MB/second)andhasamedium

range, which depends on obstructions and on data rate, but is typically up to100ft(30m)withastandardantenna,andupto500ft(150m)withlargeantennaeat the camera and base station. This is the standard used for increasinglycommonsmallwirelesscomputernetworks,suchasyoumightalreadyhaveathome.Ifyoudo,addingacameratothenetworkiseasy.

The basic networking set-up consists of the camera and its transmitter, a

Wireless Access Point (WAP), also known as a base station, arouter/hub/gateway, and one or more computers. The router distributes theimageswithinthelocalnetwork(LocalAreaNetwork,orLAN)or,throughthegateway, toa largernetwork (WideAreaNetwork,orWAN).Therearemanypermutations,andsettingupthenetworkcallsforsomeexperience.

ATypicalWi-FiNetwork

ThemostbasicnetworkofalliscameratoWAP/basestationtoFTPserver,bywhich means you transmit the images to one computer. More advanced is anetwork which also allows access, via the router/hub/gateway, to the Internetandtoseveralcomputers.Thecameraandphotographer’slaptopcanaccessallofthisviatheWAP/basestation.

EditingIncamera

Traditionally,shootingandeditingwereseparateactivities,dividedbythetimeittooktoprocesstheimages.Youtookthepicturesandlaterreviewedthemonalightboxorcontactsheet,orpossiblywithaslideprojector.

TheDSLR’s playbackmenu gives you this option right away, for better or

worse.Thebetteristhatitgivesyouthecertaintyofconfirmingtheimageandthechancetoreshootandimproveifthefirstframeisnotexactlyasyouwouldlikeittobe.Theworseisthatitcaninterferewiththeflowofshootingandevencause you tomiss shots by distracting you. It can also push you into deletingimagesbeforeyouhavegiventhemyourfullattention.

Theusefulnessof incameraeditingdependson thekindofphotographyand

on exactly what image quality you are assessing. In studio and still-life

photography—infact,anysituation inwhich there isnourgencyand inwhichyou can repeat a shot—reviewing and deleting until the image is right is asensibleprocedure. Inunrepeatablesituations,however, there isaconsiderablerisk of making a hasty, and wrong, judgment in deletions. The pressure ofavailable space on thememory card is the usual reason for doing this, but itneeds tobeexercisedwithcaution.Moresparememorycardsmaybeabetteranswer.Thecamera’sLCDscreenisausefulguidebutisbynomeansidealforexamining images, and ismuch less accurate in color, contrast, and resolvingdetail thana laptopscreenordesktopmonitor. Inparticular, checkingdetail—suchasforcamerashakeorfocusaccuracy—involveszoomingin,andthistakestimethatcaninterferewithshooting.

Data-embeddingoptionsenabledifferentkindsof informationtobeattached

to an image file for later usewhen browsing, building a database, and imageediting. Some of this is automatic (e.g. file format, image size, lens, andexposuresettings),someofituser-adjustableautomatic(e.g.dateandtime),andsomemanualinput(e.g.subjectIDandplace).Sofar,nomanufactureroffersabuilt-inGPSforautomaticlocationcoordinates,butnodoubtthiswillhappen.

Incameraediting

Atypicalincameraeditingprocedure.Outofasequenceoffiveframes,twoweredeletedimmediatelyforpoorframing,oncloserinspectionafurthertwo

weredeletedforeitherpoorcompositionorinaccuratefocusing.

Reviewingimages

Checkexposureaccuracy

Multiple-frameoption

Usefulfordisplayingsequences.

Zoom

Checkforsharpnessandmotionblur,anddetailssuchasfacialexpression.

Protection

Lockingkeyforsafety.

Delete

Themostdangerousactionwithoutanon-screencomputerreview.

Addingdatatoimages

Dateandtime

Alwaysusefulinidentifyingthesubject.Whentraveling,makesuretoallowfortimezones.

Comments

SomeDSLRsincludethefacilitytoaddashorttextcommentthatwilllaterbe

displayedinthebrowser.

Addingcomments

ThecommentfacilityinthisNikonmenuisaccessedviatheSetupmenu.Thecommentisaddedtophotostakenafterward,untilyouaskthecameratostop.Itthereforerequiresregularattentionifused.Sincecamerasdonotfeaturefullkeyboardsforobviousreasons,textentryislimitedtovideo-gamestylecursor

movement.Thistakestime,sokeepyourcommentsshortandhelpful.

PoweringtheCamera

OneofthebiggestdrawbacksofdigitalcamerascomparedwithtraditionalfilmSLRsistheirtotalrelianceonandconsumptionofpower.

Withafilmcamera,evenifthebatteriesfailedyoucouldtakeaphotoasthis

was a purelymechanical operation (although youwouldn’t be able to use the

camera’s light meter), but digital cameras require power—and plenty of it tooperateatall.Forthisreason,batterymanagementis important,nevermoresothanwhenyouaretravelingandarefarfromreliablepowersources.Thereareanumber of issues here, but all are to do with ensuring that you have enoughpowertoshootfromdaytoday.

Depending on the model, digital cameras have either custom batteries or

acceptAAsize. In thecaseof the former,youhavenochoicebut tobuy thatmanufacturer’s design, and the custom charger. The number of spare batteriesthatyouwillneeddependsonhowmuchyouintendtoshootandthefrequencywith which you can recharge. Usually, on location, it should be possible torechargeeachevening.Checkthespecificationsforbatterylifebutdonottakethe manufacturer’s claims at face value; test it for yourself. Some SLRs canacceptanadditionalAAbatterypack.Havingthisalongonatripcanbeaback-upincaseofdifficultiesinchargingthecustombatteries.

AA-compatiblecamerasoffermuchmorechoicebecauseofdifferentbattery

typesandmanufacturers,butbatterylifeislikelytobelessthancustombatteries(usuallyLi-Ion,seeBatterytypesbox).High-capacityrechargeablebatteriesaretheideal,but inanemergency,youcanusuallyfindAAalkalinesanywheretokeep you going. There is a wide choice of chargers from independentmanufacturers. It is important, however, to check themanual for batteries thatareNOTrecommended.LithiumAAsemitheatandmaynotbesuitableforallmakesofcamera.

Wherever there isaconvenientpowersupply, itmaybemoreconvenient to

use an AC adapter, usually available separately. It will also save batteries.WhicheverACdeviceyoucarrywithyou,chargerand/oradapter,youmustbepreparedfortheplug/outlettypesinthecountriesyouwillvisit.

Batterytypes

Alkaline

Widely available, not rechargeable,moderate capacity, keeps chargewhennotused.

Nickel-Cadmium(NiCd)

The least expensive typeof rechargeablebattery, gradually loses charge if notused. Suffers from“memory effect” in that if they are recharged before beingfully discharged they “learn” to have a smaller capacity. Smart chargers cansolvethisproblem.

Nickel-MetalHydride(NiMH)

MoreexpensiveandhigheroutputthanNiCd.Alsograduallylosepowerwhennotused,butdonotsufferfrom“memoryeffect.”

Lithium(Li)

Notrechargeable,light,powerful,longlife,expensive.

Lithium-Ion(Li-Ion)

Rechargeable,butlikeLithiumarelightandpowerful.Apopularchoice.

Howtorecharge

Followthecameramanual,butalsobearinmindthefollowing:

• With NiCd and even NiMH, try not to recharge before the battery is fullydischarged. With Li-Ion batteries, however, shallow discharge actuallyincreasesthecyclelife(acycleisafullchargefollowedbyafulldischarge).

• Donotovercharge.

• Smartchargersmaybeabletodothefollowing:dischargethebatterypriortorecharging, top-up charging, and switch off once a full charge has beenachieved.

• Follow a charging regime that suits the way you work. At minimum, thisprobablymeansonespare,withthedischargedbatteryputonchargeassoonaspossible.

Rating

The power capacity of a battery is measured in Milliamp-hours (mAh). Thisindicatesthebattery’soverallchargestoragecapacity,andthehigherthemAh,the longer the performance.Higher capacity batteries aremore expensive, butvaluable for digital cameras, which have a high drain. A rating of around1800mAhisconsideredhigh.

Batterymemory

NiCd batteries (but not NiMH batteries) are prone to memory problems.

“Memoryeffect,”asitisknown,isalossofcapacitycausedbyrechargingthebatterybeforeithasfullydischarged.Smallgasbubblesreducetheareaof thebatterycell’splates,andovertime,thechargebecomessmallerandthebatteryfailsfaster.Tocorrectthis,thebatteryneedstobereconditioned.

Adapters

Themostconvenientsolutiontodifferentplug/outlet typesaroundtheworldisanadapter,andthisisessentialforachargeroranyotherdevicethathasasealedcasing.Hot-wiring(attachingbarewiresfromalocalplugwithinsulatingtapetotheprongsofthechargeroradaptor)isnotrecommendedbecauseofthedangersofelectrocution.

Knowyourchargers

Ifyouarecarryingmorethanonedevice,suchasalaptoporstand-alonestorageaswell as the camera, you are likely to have similar-looking charger units orAC/DCconverters.Toavoidconfusion,andpossibledamagetocircuitry,labeleachoneclearly.

UKplugtostandard“8”plug

USplugtostandard“8”plug

Laptopcharger

THE D IGITAL ENVIRONMENT VI

ElectricityAbroad

If you’ve traveled relatively extensively, you’ll be aware that voltages vary indifferentpartsoftheworld.

Generally,voltagesaredividedbetween110–120vand220–240v.Countries

with 110–120v are principally the US and those falling under its sphere ofinfluence for reasons of proximity or history (Latin America and Japan, forexample),whilethoseon220–240vtendtobeEuropeanandformercolonies.Afewcountrieshaveboth,thoughnotnecessarilyinthesameplace.

Plugs

Thisisjustaselectionofthearrayofplugsandsocketsfromtherestofthe

worldthatIhavecollectedonmytravels.

Traveladapters

Thesesocketadaptersaredesignedtoacceptanumberofdifferentkindsofplugs.Neitherisentirelyuniversal,butbothworkwithmorethanonekindof

plugtype.

Cycles are inHertz (Hz), usually either 50 or 60.Almost all of the plug-in

electrical equipment associated with cameras and computers (chargers,transformers, and so on) are designed to switch automatically between thesevoltage ranges, so thereshouldbenoproblemson thataccount (but it’sworthchecking to make sure that you don’t have a primitive single-voltage item).Moreofanissueistheplug-and-socketfitting,asthesevarygreatly.Thebasicsolutionistoalwayscarryanadapterthatwillhandleagoodrangeofsockets.Beyond this, check the fittings in the countries on your itinerary and buy aspecificadaptor.Thefail-safe is tobuyplugs locallyandreplaceyourexistingones—butthereisariskhereinthatequipmentoftenhaspermanentlyattached,non-removableplugs.Sothatyoucancontinuetouseexistingfittedplugs,carryasimpleadapterliketheoneshownhere,withashortcableattached,andleavethewiresstrippedattheend.

There are four major plug-and-socket types, with variations within each,

particularly in the220–240v“European”group.Note thatsomecountrieshave

morethanoneplugtype.Also,somesocketsareincompatiblewithsomeplugseven of the same pin type and layout. Particularly obstructive are two-pinrecessedsockets—youmayhavetherightconfigurationofpinsonyouradaptor,butitwon’tnecessarilyfit.

Autoinverters

DC/ACinvertersmakeuseofoneuniversalpowersupply—the lighter socket in an automobile (and also someaircraft power outlets). The output plug is often eitherfigure-of-eightor clover leaf. Itmay seemodd toconvertfromDC toACwhen devices like cameras, laptops, andaccessories need DC anyway, but the variation in thevoltage and cycle of transformers makes it potentiallydamagingtofoolaroundwithDCsupplies.

DIYadapter

Withanadapterlikethis,leavetheendsofthewiresbareandattachlocalplugs

asnecessary.Mostchargersandtransformersaresealedunitsandsoshouldnothavetheirplugscutandchanged.

Plugadapters

Anadapterthatacceptstwoorthreeofyourowncountry’splugssavesthecostofhavingmorethanoneforeign-socketadapter.

Worldsockets

Acrosstheworldtherearefourbasicmainselectricitysockettypes,andvariantswithinallofthese.Whentravelingit’sessentialtohavethecorrectadapters.Thevoltage also varies from around 110v in theAmericas and Japan, to the 220-

240vsystemscommoninEurope.Manycamerachargerscantolerateeither,butyoumustcheck.

CaringforyourCamera

Thesheerquantityofelectronicsfoundinadigitalcamerainmanywaysrendersthemlessrobustthantheirconventional,film-basedcounterparts.

The convenience of not needing boxes of film on a shoot is offset by the

extremecarethathastobetakenofthesensor.Thereisonlyonesensor,andanysignificantdamagetoitwillrenderthecamerapracticallyuseless.Gonearethedays when a set of jewelers’ screwdrivers and long-nosed pliers might get afaultycamerabackontheroad.Whenadigitalcameragoeswrong,youeitherhaveasparebodyreadyoryoustopshooting.Thisplacesevenmoreimportanceonbasiccameracarethaninthedaysoffilm.

Photographinginsandyconditionsisespeciallydusty.Theimages(right)showthemarkedareainclose-up,revealingdustonthesensor.Byincreasingthecontrast,thedustparticlesbecomeeasiertosee,thoughtheireffectcanstillbe

perceivedbeforetheeffectisapplied.

Alargelyunresolvedissue ishowtokeep thesensorclean inadigitalSLR.

Unlikefixed-lensprosumermodels,SLRsarebytheirnatureunsealed,anddirtenters.Thesensorisneverdirectlyexposedtotheair,butthatdoesn’tpreventitfrom collecting particles, and this happens in two stages: when you change alens, themirror box is exposed and if the air is anything less than laboratory-clean,particlescanenter;whenthemirrorflipsupforexposure,thoseparticlesarefreetoreachthesensor.Thesensoritselfcarriesachargewheninuse,soitattracts particles, and if you make slow exposures, there’s more time for theparticlestoslippasttheflipped-upmirror.Theshadowsofsmallparticlesmaywellbeundetectableagainstdetailedpartsofanimage,andalsoiftheapertureiswideopen.Any thatarenoticeablecan,ofcourse,be removedwith theCloneStamptoolduringimage-editing,butthistakestime.

Mostcameramanufacturershavemadeattemptstoaddressthisproblem,with

varioustechnologiesthat"shake"dustfromthesensor,butthisisn'tguaranteedtoworkinallinstances.Thestandardadviceistotryandavoidchanginglenseswhenthereisdirtaround,butasthisislargelyimpractical,theonlysolutionistocheckregularlyandthentaketheinevitablerisksofcleaningthesensoryourself.Haveitcleanedbythemanufactureroranaccreditedrepairshopasoftenasispractical.

Preventingandremovingdustspots

Takethe importantprecautionofkeepingthebacksof lensesandthecamera’smirrorboxinteriorclean.Itisrelativelysafetouseacompressedaircanforthis—butusefromadistance,andhorizontally, toavoidpropellantcontamination.Forcleaningthesensor,investinahigh-pressurehandblower,anduseasmallbattery-poweredlight,forexampleawhiteLEDtorch.

Warning!

• Compressed air is effective but dangerous because of the risk of propellantsplatteringthesensor.Cameramanufacturersdonotrecommendit,butitmaybetheonlywayofremovingsomeparticles.Minimizetheriskbyholdingthecanlevelandusefromadistance.

• DON’Ttouchthesensor—EVER.Don’tuseablowerbrush.

• DON’T blow directlywith yourmouth.Any spittlewill have to be cleanedprofessionally.

Makeregularspotchecks

Atregularintervalswhileshooting(youhavetodecidehowoften,dependingonhowclean theair isandhowoftenyouarechanging lenses),checkfordirtbyshootingafeaturelesssubjectsuchasawhitewallorthesky.Anyparticleswillbemost obvious if the aperture is stoppeddown and the subject out of focus.Check initially at 100% magnification, scrolling from one corner across theentireimage.Whenpossible,alsochecktheimageonacomputerscreen.

Cleaningthesensor

Althoughthesensoritselfisprotectedbyalow-passfilter,whichaffordssomeprotection, the filter itself is delicate, and scratching means expensivereplacement, hencemanufacturers’ warnings against touching it. If you detectdirtinanimage,cleanthesensorasfollows:

• Makeamentalnoteofwhere in the frameare theobviousparticleshadows.BecauseanSLRimageisinverted,theactualparticleswillappearininvertedpositionswhenyouexaminethesensor.

• Findaclean-airareaandremove the lens. Ideally,put thecamerabodyonatripodsothatyoucanworkwithtwohands.

• Followthemanufacturer’sinstructionsforlockingthemirroruptoexposethesensor.Thisisimportant,becauseifyousimplysettheshutterspeedtoBorT,the sensorwill carryacharge thatwill attractevenmoredirt.Typically,youwouldneedtoconnectthecameratoanACadapter.

• Shineabright light, ideallyapoint source,onto thesensorand inspect fromdifferentangles.

• Use a hand-operatedbulbblower as shown. If thisweak flowof air fails toremoveeverything,consider(atyourownrisk)thenextstep—compressedair(seeWarningboxopposite).

On-cameraFlash

MostdigitalSLRsfeatureabuilt-in,pop-upflashunit,andalthoughthistypeofflashisoflimiteduse,itcanbehelpfulasfill-inflashforbacklitsubjects.

Furthermore,ifthereareabsolutelynootherformsoflightingonoffer,atleast

apop-upflashgivesyoutheabilitytocaptureanimage,asbasicasitmaybe.

On-cameraflashofthiskindhastheinevitabledrawbacksoffrontal lighting

(almostshadowlessandfallsoffinproportiontothedistancefromthecamera).Atthesametime,on-cameraflashgivesclear,crispresultswithbrightcolor,so

that,forexample,itoftenworkswellforclose-upshootingofcolorfulsubjects.High-end digital SLRs with built-in or dedicated flash units use a variety ofsophistications to improve exposure accuracy, including focus (to favor thedistancetothechosensubjectinascene).

On-cameraflashdrawbacks

1Exposureisgoodforonedistanceonlybecausethelightfallsoffalongthelineofview.Iftheforegroundiswelllit,thebackgroundwill typically be dark,while obstructions in front of the subjectcan easily be overexposed. Solution: Rearrange camera position andcomposition;changeflashmodetofill-insothatexposureislongenoughfortheambientlighting.

2 Specular reflections in shiny surfaces facing the camera. Solution: Changecameraposition;retouchhighlightsinimage-editing.

3 Red-eye; reflections from the retina, particularly with a longer focal lengthlens.Solution:Somecamerasofferapre-flashtomakethesubject’siriscontract,butthisaddsadelay;retouchinimage-editing.

4Flat,shadowlesslightthatgivesapoorsenseofvolume.Solution:Useflashasfill-in;increaseISOsensitivitytorecordmoreambientlight.

Guidenumber

Thisisthestandardmeasurementoflightoutput,andvariesaccordingtotheISOsensitivity. It is equal to the aperture (in ƒ-stops) times the flash-to-subject

distance(inmeters,feet,orboth).Atypicalrating,forexample,mightbe“GuideNumber 17⁄56 at ISO200,”meaningmeters/feet.Divide the guide number bytheapertureyouareusing to find thedistanceatwhichyoucanuse it. In thisexample,ifyouwereusinganapertureofƒ/4,itwouldbe14ft(4m).

Usingbounceflash

Theprincipleofbounceflashistoaimtheunitataceilingorwallratherthanthesubject,totakeadvantageofthemuchmorediffusedlightfromthisreflection.Itgreatlyreducesthelightreachingthesubject,andyoushouldalsocheckthattheceilingorwalliswhite,orexpectacolorcast.Afewcamerashavethefacilitytoanglethehead,butotherwisethisisafeaturefordetachableon-cameraunits.

Rear-curtainsync

Aspecialvariationoffill-inflashisstreakingwithrear-curtainsynchronization.Inthis,theexposureandflashoutputarebalancedasforfill-in,buttheflashistimedat theendof theexposure. If there ismovement,either in thesubjectorbecauseyoumovethecamera,therewillbetrailsoflightthatendinasharplyfrozenimage.Thisworksparticularlywellatnightinlocationswheretherearebrightlights—forinstance,apanningshotofamotorcyclewithitslightson.

Multipleflash

Some advanced detachable camera flash units featurewirelesslinking.Theunitmountedonthecameraservesasthe “commander,” from which any number of other,independentlymountedunitscanbecontrolled.Theinitialflash from this unit triggers the others via their remotesensors. With the Nikon SB-800 unit shown here, flashunitsaregrouped,andtheirflashmodesandoutputlevelscan thenbealteredfromthe“commander,”and theirchannelscanbeassignedalso.

Fill-inflash

Oneofthemostsuccessfulusesofon-cameraflashisasshadowfill.Inthis,theshutterspeedissetlowenoughfortheambientlightingacrossthescene,andasmaller-than-usualdoseof flash isadded.AllSLRshaveaprogramfor this inthemenu,butastheexactbalancebetweenflashandambientlightisverymuchamatterofpersonal taste, the ideal is to trydifferentvariationsandcheck the

resultsonthespotontheLCDscreen.Forfullcontrol,useamanualexposuresettingandlowertheflashoutputbyincrements.

Off-cameraFlash

Ifyou’reafter thehighest-qualityimageinstudioconditions, thenyou’llreallyneedtoturntooff-cameraflashunits.

The advantages of using professional high-output flash are: precise color

temperature(daylight),shortdurationtofreezemostmovement,andaquantitythat allows it tobediffused, reflected,orbounced, andyet still providesgooddepthoffield.

Typical studio systems are split between those inwhich several flash heads

are servedby a powerunit, andmonoblocsdesigns, inwhich the transformer,rectifier, capacitor, and flash tube are all housed in one self-containedunit. Inaddition, there are portable flash systemswith amuch higher output than theusualdetachableon-cameraunits,usingbatterypacks.

With digital SLRs, in-camera color balance and generally higher base ISO

sensitivity admittedly reduce the value of these, but not much. The olddisadvantageof flash—thatyoucouldneverbeabsolutelycertainof the resultunless you did Polaroid tests—has disappeared. Digital SLRs make flash adreamtouse.

More than anything, it is the endless variety of light fittings that make

professionalflashunitssouseful.Notonlyistheoutputhighenoughtosurviveheavydiffusionandreflection,butthelowtemperatureatwhichthelightsworkmakeitpossibletoenclosethemwithoutrisk.Thebetterstudioflashunitshaveaslavesyncbuiltin,todoawaywithonesetofmessycables.Inatypicalstudio

flashsystem,thepowersupplyisACatarelativelylowvoltage.Thefirstpartofthecircuitryisatransformertostepupthevoltageandarectifier(morethanoneinlargeunits)toconverttheACtoDC.Thisuni-directional,high-voltagesourcethen supplies the capacitorwhich stores the charge.When triggered, the high-voltage output in the capacitor is discharged through the flash tube.Output ismeasuredinwatt-seconds,orjoules,andtypicalunitsarebetween200and1,000joules.Tomakeuseoftheextremelyhighoutputofthemainsflashcapacitors,theflashtubesaremuchlargerthaninon-cameraunits,andoneresultofthisisthat thepeakflashduration is longer than thatofanon-cameraflash,which issometimesasslowasafewhundredthsofasecond.

Studioflash

Seriousindoorphotographywillmakeuseofdaylight-balancedadjustablelights

andavarietyofmodifiers.Mostofthesewillfeaturemodelinglights:a

andavarietyofmodifiers.Mostofthesewillfeaturemodelinglights:acontinuouslighttohelpset-up.

Snoot

Honeycomb

Flashmeters

Despite modeling lamps, which are standard on studio units, previewing theactual lighting effect is still one of the problems with flash—and calculatingapertureagainstoutput evenmore so.Althoughhit-and-miss calculation isnotdifficultwithadigitalSLR,itmaystilltakeafewexposurestoarriveattherightsettings.Aflashmeterisessentialforregularstudiophotography,andthemostusefulmethod is to takean incident light reading. Incident readingsareof thelight falling on the subject and so are uninfluenced by the tone, color, orreflectivityofthesubjectitself.

Softbox

ContinuousLights

Onedrawbackwithflashunitsisthatyoucan’taccuratelypredicthowtheimageisgoingtolookuntiltheflashhasfired.

Althoughinthesedaysofinstantreviewit’seasytoadjusttheunitsandshoot

again,theadvantagewithcontinuouslightsisyoucanseeexactlywhatlightingeffectyouaregettingasyouadjustthelights.Thisalsomakesiteasytocombinewithexisting,ambientlight.

Asfor types, incandescent is thetraditionalsource,butfluorescentandHMI

are becoming increasingly popular in studios. The most efficient type ofincandescentlightingisthetungsten-halogenlamp,whichusesacoiledtungstenfilamentasinordinarytungstenlights,butburningatamuchhighertemperatureinhalogengas.Asaresult,thelightoutputandcolortemperaturestaymoreorlessthesamethroughouttheirlife.Availablewattagesrangefrom200to10,000,butforstillphotography2,000Wisaboutthehighest.Usedalone,incandescentlamps simplyneed a 3,200K“incandescent”white balance.However, usedonlocation, they are often in combination with existing daylight, fluorescent, orvaporlighting,andinthiscaseitisusualtofilterthelampstowarddaylight.

Anewerdevelopment,particularly relevant todigitalphotography, inwhich

thecamera’swhitebalancesettingscan takecareofcolordifferences, ishigh-performance fluorescent. The lamps used are flicker-free, almost as bright asincandescent,color-balancedfor5,400Kor3,200K,aswellasbeingcoolerandlessexpensivetorun(thoughmoreexpensivetobuyinthefirstplace).

Fluorescentlighting

ThisLupoQuadrilight delivers light at a temperatureof 5,400Kelvin, ideal

forproductshots.Themetallicbarndoorsallowcontrolofthespread.

Utilizingdaylight

Continuous light is ideal for interiors, where the size of the subject and thecomplexrelationshipwithotherexistinglightsources(suchasdaylightthroughawindow)makeitmucheasier ifyoucansee theeffectpreciselybyeye.Theimportantprecautionwithincandescentlampsistobalancethecolortemperaturewithagel.

Flashorcontinuouslights

Flash:Pros Flash:Cons

Freezesmovement Smallunitsgivenopreview;othershavemodelinglampsthatcallfordim,ambientlighttoshowtheeffect.

Cool Fixedupperlimittoexposure,beyondwhichneedsmultipleflash.

Daylight-balanced,mixeseasily Technicallycomplex.

Highunitcost.

Tungsten:Pros Tungsten:Cons

Yougetwhatyousee. Notbrightenoughtofreezefastmovement.

Exposureadjustmentssimple—justchangeshuttertiming

Hot,socan’tacceptsomediffusingfittings,anddangerousforsomesubjects.

Mechanicallysimpleandeasytouse. Needsbluefilterstomixwithdaylight.

Somemakesverysmallandportable.

High-performancefluorescent:Pros High-performancefluorescent:cons

Yougetwhatyousee. Notbrightenoughtofreezemovement.

Exposureadjustmentssimple—justchangetheshuttertiming.

Bulky.

Daylight-balanced,mixeseasily. Highunitcost.

Mechanicallysimpleandeasytouse. Tubedimensionsrestrictlightdesign.

Lowrunningcosts.

Cool—noneoftheheatproblemsofincandescent.

HMI:Pros HMI:Cons

Exactlyasfortungsten,butcool. Expensive.

Needsabulkybalast.

ReflectorAngle

Incandescent light housings have a reflector behind the lamp to increase itsoutputandhelpcontrolthebeam.Mostgeneral-purposehousingshavereflectors

thatgiveaspreadofbetweenabout45°and90°.Thebeampatterncanoftenbeadjustedbymoving the lamp inandoutof the reflector,orbymovinghingedpanelsinfront.

Daylightcontrolandtungstenconversionfilters

Thereisawiderangeofheat-resistantgelsavailable,thataredesignedtofitinfront of incandescent lamps to adjust their color temperature. They are fittedeitherincustomholdersorinanoutrigframethatattachesinfrontofthelight.

Themostcommonlyusedgelis“fullblue,”whichisdesignedtochangethe

color temperature of an incandescent light from tungsten (3,200K) to daylight(5,500K).Analternativeisadichroicfilter—apartialmirrorthatfitstothefrontofthelamp,reflectingredbacktothelampandpassingblue.

Forpartialconversion,a“halfblue”willadjustthetemperaturefrom3,200K

to4,100Ktocompensateforvoltagereductionorretainsomeofthewarmthoftungstenlampswhenmixingthemwithdaylightorflash.

Fluorescentlights

High-output, flicker-free, daylight-balanced tubes make fluorescent lights arealistic alternative to incandescent, with some clear advantages. The light iscool,andsoconvenientforstill-lifesubjects.Inthesedesigns,severaltubesarearrangedinparallelwithmirroredreflectorstoformalightbank.

LupoQuadrilightandSuperlights.

Tripods

There’s no doubting that a tripod will provide cleaner, sharper images,particularlyinlow-lightconditionswhenaslowerthanidealshutterspeedhastobeused.

However,whentravelingtheycanbeawkward,somuchdependsonthetype

ofshotsyouexpecttodo.Tripodefficiencydependsontwothings:designandmaterials.The firstessentialquality forany tripod,as foranybridge, is that itstaysfirmandstillunderaverageconditions.Theacidtestistofixthecamera,usea longfocal length,andtapthefrontof thelenswhile lookingthroughtheviewfinder.Commonsensewillshowwhethertheslightvibrationisacceptable,but to make sure, shoot a few times at around 1/60 sec to 1/125 sec whiletapping the lens.Examine the imageson thecomputerat100%magnification.Torsion is another indication of tripod stability—with the camera detached,grasptheheadfirmlyandtrytotwistitclockwiseandcounterclockwise.There

shouldbenosignificantmovement.Notethatcenter-poleextensionscan,ifnotvery well built, reduce stability. This is particularly true of rack-and-pinionmovements operated by a rotating lever; convenient, certainly, but notnecessarilysolid.

Tripodheadsareasimportantasthetripoditself,andaweakheadwilldestroy

anyadvantageyouhavefromastrongtripod.Therearetwobasicdesigns:pan-and-tilt,inwhicheachmovementismechanicallyseparate,andball-and-socket,whichallowsfullplayineverydirectionwithoneunlockingmovement.Whichisbetterisentirelyapersonalchoice.

Inastudio,aheavy,solidlybuilt tripod isanobviouschoice,andfor large-

formatcamerasastudiostandisevenbetter.Locationshootingortravelingoveraperiod,however,putsapremiumonlightweightconstruction.Justasthereisnopoint inevenconsideringa lightweight tripod that is too flimsy tohold thecamerafirmly(ortooshortfornormaluse),neitheristhereanyreasontohaveatripodthatisover-specifiedforasmallcamera.Costenterstheequationbecausestrong, lightmaterials are available and they are alwaysmore expensive. Thematerialofchoice for tripods iscarbon fiber (30% lighter thanaluminum,andmore rigid), and for heads, magnesium alloy, but the price difference fromstandardisconsiderable.Foralltheabovechoices,ifyouarebuyingatripodandhead,comparemodelssidebysideforshake,torsion,weight,andsoon.

Therearegood impromptualternatives to tripods,dependingonhowslowa

shutter speed you need. To hold the camera more steadily, a rolled-up cloth,jacket,orsoftcamerabagonasolidsurface(suchasawallorpartofavehicle)works verywell—if you press downon the camera or lens as you shoot, youmaybeable touseshutterspeedsasslowasonesecond.Very longexposuresare possible if your camera accepts an electronic cable release; find a solidsurface at aworkableheight, prop the cameraupwithwhatever ishandy, andtriggertherelease.Toavoiduncertaintyintheseconditions,shootseveraltimes.

Focallengthandcamerashake

Camera shake is the condition that tripods and othersupportsare intended toprevent,and its symptomsareablur of a characteristic “doubled” kind across the entireimage.As long focal lengthsmagnify images, they alsomagnifyshake.Long focal-length lenses (forSLRs)alsotendtobeheavy,whichcanbeanadvantageonatripodas theweightmakes the setupmore solid, provided thatyou mount the lens near its center of gravity (use thelens’sowntripodbush).

Usingatripod

• Lowismorestablethanhigh.

• Make sure that the surface is steady. Sand shifts, as do loose woodenfloorboards.

• Adjust the legs so that the platform (immediately below the tripod head) islevel.Donotlevelbythetripodheadalone.

• WithalonglensonanSLR,useitstripodbushratherthanthatofthecamera,inordertogetclosertothecenterofgravity.

• Shelterthetripodfromwind.

Shutterspeedstowatch

Fast shutter speeds don’t need a tripod, and at very slow speeds, such as asecondorlonger,thecamerahastimetosettledownaftertheshutterisreleased.Moderately slowspeeds,however, suchas1/30secand1/15sec,canproducecamerashakewithalongfocallength,evenonatripod.Checkforthis.

Headtypes

Ballheadsallowmovementinalldirections,whereastwo-andthree-wayheadsoffermorecontrolineitherdirection.

Twowayhead

Ballhead,Three-wayhead

Monopods

Asingle adjustablepole can improve the shutter speed atwhichyou shoot byaboutafactoroftwo.Ifyouarehiking,lookforawalkingpolethatisequippedwithascrewthreadthatwillacceptasmalltripodhead.

Mini-tripods

Surprisingly useful, and light enough to carrywithoutnoticing,mini-tripodsmaylackelevation,butthereareoften surfaces to give height, such as a vehicle roof.Onegoodtechniqueistopressthemini-tripodagainstaverticalsurface,suchasawall.

THE D IGITAL ENVIRONMENT PART VII

CameratoComputer

Manyhigh-enddigitalcamerascanbetethereddirectlytoacomputerthroughahigh-speedcable, suchasFireWireorUSB,and thenwith thehelpof specificsoftware from the cameramanufacturer, the camera can be operated from thecomputer.

Thiskindofuseisintendedmainlyforstudioshooting,althoughwithalaptop

computer, there areno real limits to thekindof location. Itmakesmost sensewhenthecameraissetuponatripodinfrontofastaticsubject,asinastill-lifeset, and in this kind of circumstance, the computer really can add a newdimensiontophotography.

TheexampleonthefollowingpagesisanautomobileshootinaNissanauto

showroom, using available tungsten lighting, with muted daylight inevitablyleakinginfromoutside.Infilmphotography,thefirststepswouldbetomeasurethe light and the color, set the aperture and shutter speed accordingly, andchoose a combination of filter and film (either Daylight or Type B). Then aPolaroidtestor, if therewerenoPolaroidbackforthecamera(heavenforbid),widebracketingofboththeexposuresandthefiltration.

Digitally, the exposure and color balance issues are taken care of by the

preview,butthestrikingadvantagesofshootingdirecttothecomputerarethatthe image can be viewed large and accurately on the calibrated (of course)screenofthelaptop.Withthecameraonitstripod,everythingcanbeadjustedincomfortfromthecomputer,usingtheappropriatesoftware—inthiscase,Nikon

Capture3.5.Thecontrolpaneloffersaccesstoalltheessentialsettings:theISO-sensitivity, shutter speed, aperture, focus, and color balance. A click of themousefiresthecamera.

The laptop’s LCD screen is more accurate and convenient for judging the

imagethanthecamera’sownsmallLCDscreen,particularlyinthecriticalareasofhighlightexposureandcolorbalance.Resultscanalsobejudgedbylookingatthe histogram. Because the image that appears on the screen is large, theadvantageofbeingabletogointotherealsetandalterthingsisclear.Ifaclientispresent, this is alsoaveryusefulwayofhaving the imageapprovedon thespot,withnouncertainty.Evenifthey’renotpresent,therearemanymeansofinstanttransfer.

Computercontrol

Mostmanufacturersprovidesoftwaretoenablethecameratobeuseddirectly

fromthecomputer.

1Halfofthemenuoptionsaredisplayedonthisfirstcamera-

controlscreen,titledExposure1,andincludeexposuremode,shutterandaperturesettings,andcompensation.

2TheImageProcessingwindowgivesaccesstosharpening(normallyusedwithcautionwhenshooting),tonecompensation(affectingthecontrastrange),andthecolormodeforlaterimage-editing.Hueadjustmentallowsfurtherfinecontrolovercolor,andnoisereductionischeckedbydefault.

3WhentheShootorAFandShootbuttonisclicked,thestatus

windowshowsthedownloadingprogressastheimageissaved,nottothememorycardinthecamera,buttoaselectedfolderonthelaptop'sharddrive.

4Inshootingahigh-performanceNissancar,thetechnical

issuesarehighcontrast(holdthespecularhighlights)andcolorbalance(mixedtungstenandcloudydaylight),callingforacarefullychosenwhitebalancecompromise.

CanonuserswillfindatoolcalledCameraWindowwiththeirapplicationsuiteswhichcanperformsimilarfunctionsusingasimulatedLCDdisplay.Here,forexample,theexposurecompensationhasbeenselected,andcannowbeadjusted

usingthecursorkeysoriconsbeneath.Thelargeroundbuttonactsastheshutterrelease,afterwhichtheresultingimageispassedtotheBrowser

program(below).

TravelingwithEquipment

On the whole, digital equipment is a little lighter than conventional kit.However,thankstotheelectronicsinvolved,digitalkitrequiresmoreaccessoriesintheformofbatteries,cables,andadaptersifyou’retravelingabroad.

Thismeans that there isanevenmoremarkeddifferencebetweenwhatyou

need to travelwith andwhat you need for actual shooting. So itmakesmoresense toconsiderdividing thepackingbetweenacase for transportationandabagforshootingwhilesimplywalkingaround.Abackpackisworthconsideringfor hiking, climbing, and other outdoor photography. For transportation,well-padded protection is a high priority, given that digital equipment tends to bedelicate.

Thethreeworstconditionsfordigitalequipmentarewater,dust,andheat,and

thebestprotection for the first two is aproperly sealedcase—meaningwitha

gasketorrubberringofsomesort.Watershortselectricalcircuitsandcorrodesmetalparts(thoughtherearefewerofthesethanthereusedtobe).Saltwateristheworstofall,whilelightrainsimplyneedswipingoff.Fullimmersion,ontheother hand, is likely to cause awrite-off. If it happens, remove the lens, openeverythingthatcanbeopened,anddrythecameraquickly.

Rigidplasticcases,likethisfromPelican,areasuperblyprotectiveenvironment

foracamera,buttheirpaddingcanbelimiting.

Casesmadeoflight,shinymetalsreflectheatandareverysturdy.Someare

evenstrongenoughtostandonforabetterview.

ThisLatigidcasefromLightwareispadded,butdesignedtobestacked.

The danger of dust and sand is that particles can work their way into the

camera’s mechanism, causing scratching and jamming of moving parts—andmostimmediatelyadheretothesensor.Evenashortexposurecanbedamaging,so in dusty conditions keep the camera wrapped or sealed except for actualshooting.Sandonbeachesisinsidiousbecausesaltmakesthegrainssticky.

Heatcanaffect theelectronicsat temperaturesoftypically104˚F(40˚C)and

more. A bright metal case is better at reflecting heat than any other kind. Insunlightinhotclimateskeepcamerasintheshadewhenyouarenotusingthem.

Wheretheairishumidaswellashot,packsachetsofsilicagelinwithcameras—itscrystalsabsorbmoisture.Whenthesilicagelhasabsorbedallitcan(sometypeschangecoloratthispoint),dryitoutinanoven.

Cold weather is less of a problem in itself, although batteries deliver less

powerandneedtobereplacedmorefrequently.Cellcapacityisverylowbelow-4˚F (-20˚C), and a little lower than this the electrolyte will freeze (althoughwhen it thaws, it will start functioning again). More serious potentially iscondensation caused by moving equipment between cold exterior and heatedrooms. After cold-weather shooting, warm the camera up slowly, or wrap ittightly in a plastic bag so that condensation forms on the outside rather thaninside.

Security

Apadlockisavitalprecautionwhentraveling.Regrettablythereareanumberofplaceswhereyoushouldbeonyourguardagainsthotelstaffandevenairport

workers.

Packingchecklist

•Camerabody

•Sparebattery

•Batterychargerandcable

•Plugadapter

•USBorFirewirecable,camera-to-computer

•Laptoporimagebank

•Memorycards

•Cardreader

•Lenses:zooms,wide-angle,telephoto,macro,shift

•Blowerbrush

•Lint-freeclothforcleaning

•Tripod

•Cablerelease

•AC/DCconverter

•UVfilters

•Polarizingfilter

•Neutralgradfilter

•Rubberpadforremovingstuckfilters

Imageediting

Intheworldofconventionalfilmphotography,thephotographer’sresponsibilityin terms of the final image creation endedmore or lesswith composition andaccurate exposure. Processing the film and handling the printing was usuallydoneviatrustedandreputablethirdparties,butwithdigitalimagingallthathaschanged.Today’sphotographermustnowbefullyacquaintedwithawholenewraftofdigitalstepsandtechniquestoensureimagesappearastheyshould.

Thesenewdigitalstepsareoftencollectivelyreferredtoas“workflow”andneedto be undertaken in an orderly fashion. Of special importance is smoothlyintegrating themechanical sideofphotographywith thevariousproceduresonthecomputer.Softwareis,indeed,thebignewaddition,demandinganewsetofskills so you can edit your images and show them off in their best light—whether for print or for screen. There are several good software packages formaking adjustments to images, but Adobe Photoshop dominates, and isconstantlyimproving,versionbyversion.It’scommonsensetoassumethatmostphotographerswilluseit,andtheexamplesinthissectionfollowsuit.Theaimisto lay out the sequence for handling the image as itmoves from one state toanother,andfromonedevicetoanother,tobringoutthebestinthefinaleditedversion.

TheDigitalPhotographyWorkflow

Much of the digital photography workflow is concerned with preparing the

image for final viewing. This involves ensuring that images have accuratecolors,afulldynamicrange,aresharp,freefromblemishes,andsoon.

Because so much can be done once the image is on a computer, for most

conventionalphotographersitmeansaradicalrethinkintheirworkingmethod.It stands inmarked contrast to shooting color transparencies,where very littleflexibility in processing means that the photography virtually ends at themomentofshutterrelease.Ifanything,itismoreakintothekindofblack-and-whitephotographypracticedwithaneyetolengthydarkroomwork(thinkAnselAdams).Digitalworkflowneedstobeplanned,andthatimpliesshootingwithagoodideaofwhatcan(andshould)bedonelater,onthecomputer.Thisis thethinkingbehind shooting inRaw format, inwhichmost of the settings canbealteredlater.WhenyoupresstheshutterinRawmode,asmuchinformationaspossible is transferred to the file: the highest bit-depth color your camera iscapable of recording, the shutter speed, exposure program, ƒ-stop, aperturevalue,ISOsetting, lens,flash,andsoon(eachcameramodelcreatesaslightlydifferentRawfile).Even ifyouareshootingJPEGs, therearemanysteps thatcanbetakenonthecomputertogetthebestoutofthecapturedimage.

FlexibleRaw

Knowing the power of the imaging tools available in programs such asPhotoshop,doesn’t itmakemoresense todivide theworkbetweenthecameraand thecomputer? Ifyoucanmoreaccuratelyset thebrightness rangeand thedistribution of contrast using Photoshop, isn’t it better to adjust the camerasettingssothatyoucapturethemaximuminformationratherthangoforthebestappearancestraightoutofthecamera?

Comprehensiveworkflow

Indigitalphotography,theimageworkflowtypicallygoeslikethis:

1Shooting,ideallyasRawfilesforlatercontrolandflexibility.

2Transfer imagesfrommemorycard toanappropriatefolderon thecomputerhard drive: from the camera, or from the card using a reader, or via anintermediatestoragestepsuchasaportableimagebank.

3Examine the images inabrowser,deleteanyobviousmistakes, rotatewherenecessary,renameandreorderifappropriate.

4Basicedittoidentifyselects.

5* Make a contact sheet and/or low-res JPEGs to send to client for review,possiblywithselectedoptimizedimages.

6*Clientreviewslow-resimagesandrequestsoptimizedTIFFsofsome.

7OptimizeselectsbyopeninginaRaweditorandadjustingwhitebalance,hue,exposure, shadows, brightness, saturation, and contrast. Save as 16-bit RGBTIFFs.

8Continueoptimization inPhotoshop,adjustingblack-and-whitepoints, color,curves, and the saturation and brightness of individual hues. Retouch artifactsincludingsensordust.Possiblyreducenoise.

9Wherenecessary,performmoreextensiveimageeditingtocontent.Ifeditingprocedureshadbeenpre-plannedwhenshooting,undertakethese.

10Proofcertainimagesondesktopprinter.

11Embedcaptioninformation,andsaveandarchivefinalimagesas8-bitRGBTIFFs.AlsoarchiveRawfiles.Enterintoimagedatabase.

12*DeliverfinalRGBimagestoclient,whosignsoffonthem.

13*Pre-presspreparationof images, includingCMYKconversion,appropriatesharpening,anddotgain.

14*Colorproofs.

15*Corrections.

16*Pressdate.

*Professionalassignment.

Minimumworkflow(excludingRawfiles)

1Shooting.

2Transferimagesfrommemorycardtoharddrive.

3Examinetheimagesinabrowser,deletemistakes,rotate.

4Identifyselects,optimize,andcaption.

5Saveandarchiveallimages.

Typicalhardwareworkflow

Onceapictureistakenandprocessedbythecamera,itisstoredonthememorycard. This is transferred to the computer via a card reader (or direct cableconnection) before being processed, and then sent to the final destinationmedium.

TypicalSoftwareWorkflow

ComputerRequirements

Ifyou intend toundertakeallyourownpost-productionwork—inotherwordsprepare your images for final viewing— you’ll need a high-specificationcomputer system. This is because digital image files are large (and gettinglarger), are often very complex, and require accurate rendering and powerful(memory-hungry)softwaretoeditthem.

Image editing, as we’ll see, is the primary function for computers in

photography,butotherkeysoftwareapplicationsarefordownloading,browsing,databases,printing,slideshows,scanning,archivingontoCDs,DVDs,or tape,andaccess to theInternet, includingsending images toothercomputers.Thereare, in addition, verymany plug-ins intended toworkwith yourmain image-editingsoftware—theseareindependentlywrittenapplicationsthatdonotstandalone,butareaccessedthroughPhotoshoporwhicheverimage-editingprogramyouchoose.

The key performance issue is processing speed,which depends on the chip

and is measured in megahertz (MHz) or gigahertz (GHz). It is the main

determinant of the cost of the machine, and for processing photographs, thefasterthebetter—andwithnoupperlimit.Multi-taskingisanotherstrategyforimprovingtheworkflow,permittingoperationssuchasbatchprocessingtoruninthebackgroundwithlittleeffectonotherapplicationsthatyoumightbeusing.Active memory is known as RAM (Random Access Memory), and incombinationwith the processing speed determines how quickly you can openandmanipulate images.Likeprocessing speed, it is almost impossible tohavetoo much, and the ideal for image-editing is about five times the size of theimagefile.Thisfilesizecaneasilygrowbeyondwhatyoumightexpect.Takea10-megapixel camera. The RGB image from this will be 30MB (10 × 3channels)in8-bitcolour,but60MBifyouchoosetosaveas16-bit.Ifyouthenstarttoaddlayers,itwillbecomemuchbiggerstill.Andyoumightwellwanttoopenmorethanoneimageatatime,forcomparisonorcompositing.Attheveryleast,youwillneedRAMofthreetimestheimagesizeifyouaretoworkwithintheactivememory,becausetheprogramneedstoholdcopiesoftheimagewhileyoumake changes. A workaround to insufficient RAM is virtual memory, inwhichfreespaceontheharddriveisusedtemporarilyasmemory—useful,butitslowsdownperformance.

In choosing an operating system—which essentially means choosing the

computer itself, consider the following: performance, ease of use/ease ofinterface, software availability, and cost. Of the normally available operatingsystems, Windows is by far the most common, although Apple Macintoshmachinesaremorewidelyusedby imagingprofessionals for reasonsofspeed,ease of use, and tradition.Unix and Linux are extremely robust systems (andindeedMacOSXisbasedonUnix),butsufferfromhavingalimitedrangeofimage-editing software written for them. Photoshop is available forWindowsandMacandworksequallywelloneitherplatform.

Peripherals are the extra pieces of hardware that connect to the computer.

Whatyouchoosedependsonwhatisalreadybuiltintothecomputer(perhapsaDVDwriter),andonyourpreferredwayofworking (suchasusingagraphicstabletinsteadofthemouse).

RAMallocation

Forthehighestperformanceinimageediting,allocatethemaximumRAMandahigh cache size to the application, and run that alone. On the Mac go toPhotoshop > Preferences > Performance... (the Preferences option is accessedfromtheEditmenuontheWindowsversion).Fortechnicalreasons,Photoshopislimitedtoaccessingamaximumofabout4GB.

Memory

RAMchips,inthiscaseintheformofaDIMM(DualInlineMemoryModule),arerelativelyeasytofit.Cardslikethissimplyplugintoslotsinsideyour

computer.

Graphicstablet

A cordless stylus and graphics tablet allow an intuitive way of working,particularlyfordigitalbrushwork.Thestylusresponsecanbecustomizedtothewayyouwork,forinstance,alteringtheangleoftiltatwhichitwillrespond,andthetippressurefromsofttofirm.

Long-termstorage

Externalharddrivesarefastbecomingtheonlysensiblearchivingmethod,andcapacities are increasing all the time. RAID units (Redundant Array ofInexpensive/IndependentDisks)aregroupedharddriveswithacombinationofsoftwareandhardwarethatpreservesdataintegrityincaseofthefailureofone.Asimpleralternativeismirroredharddrives.SomephotographersuseDVDsas

anextralevelofarchivingsafety.

MonitorTypes

If undertaking seriouspost-productionworkonyour images, it’s essential thatyougiveseriousthoughttothetypeandqualityofyourmonitor.Themonitoristheprimaryinterfacebetweenyourimagedataandhowitwilleventuallyappearinprintoron-screen.Sparenoexpenseonit.

Thefourmaindecisionsaresize,brand,andmodel,andwhethercathode-ray

oractive-matrixLCD(alsoknownasTFT).

CRT(cathode-raytube)monitorsfollowthetraditionaltelevisiondesign,with

electrongunsat thebackof the tube firing toward the insideof thephosphor-coatedscreen.Thisistried-and-testedtechnology,notparticularlyexpensive,butthenecessarydepthof the tubemakes themonitorsbulky—andlargedisplays,suchas20in,areheavypiecesofequipment.

LCD displays are the alternative, and their technology has improved to the

pointwherethebestmodelsoffersuperiorbrightness,saturation,andsharpness,allwithoutbulk.Anearlierdisadvantagewasthelimitedviewingangle,whichmeantthatevenaslightshiftinyourpositionalteredtheapparentbrightnessofthe image on the screen. This was notmerely inconvenient; it made accuratejudgmentofbrightnessandcolorverydifficult,butnow,ingooddisplays, thishas been overcome. Failed pixels, appearing as white dots, are also now lesscommon—thereshouldbenomorethanfouronanewdisplay.Laptopscreenswithoutbacklighting,however,arestillnotuptostandardforaccuratecolorandbrightness judgment. If youuse a laptop for shooting anddownloading, try todefer optimization until you can put the images on the main home or studiocomputer. Otherwise, limit yourself to adjustments that can be made by thenumbersinsteadofvisually,suchassettingblack-and-whitepoints.

It is essential to calibrate monitors as a first step toward overall color

accuracy.Attheveryleast,thismeansrepresentingneutralgraysasneutral,andideally this should be not only for the midtones but also for the blacks andwhites.Thisisdealtwithonthefollowingpages,buttheconditionsunderwhichyou view themonitor are also important. There are two issues here, and bothrelatetothesurroundings:Oneistheambientlightlevel,theotheristheambientlight color. Perception is always relative, and both brightness and color arejudgedbytheeyeinrelationtoadjacentpartsofthescene.Ifthesurroundings,forinstance,haveayellowishcast,theeyewilltendtoover-compensateandseethescreenasmorebluethanitis.Whatmattersmostisconsistency.Theeyeisverycapableofaccommodatingtodifferentlightlevelsandcolorcasts,perhapsrather too capable.As a rule of thumb, try to keep the brightness level in theroomwhereyoukeepthecomputeratabouthalfthelevelofthemonitorscreen.Acompletelydarkenedroomwillallowyoutodistinguisheveryshadowdetail,but itwillalsopushyoutoedit imagesthatwillappear toodarkundernormalconditions.Abright roomwill have theopposite effect.The ideal is completeartificial lighting with daylight color-corrected lamps, but this may well beimpractical, not to mention less pleasant than an office with a view of thegarden.Consider translucent neutral roller blinds to cut down direct sunshine.Thecolortemperatureofdaylightfluctuatesalso,sotakethisintoaccount.Forthe same reasons, it is best to have neutrally painted walls, and above all, aneutralgraydesktoppattern.

Monitorsetup

The eye is so good at adapting to different light levels and color casts that itactuallyworks againstus in settingup themonitor.The followingprecautionsareessential:

1Thelightlevelsintheroomshouldbelow,meaningaroundhalfthebrightnessofthescreen.Toobrightandyouwillnotbeabletoregisterpureblack,toodarkandyoumayendupeditingtheimagesoitistoodark.

2 The room lighting should be somewhere close to “artificial daylight”—D50/5,000K.

3Theroominteriorshouldbeneutral,notbrightlycolored.Thesameappliestoyourshirtorblouse—itwillreflectalittleinthescreen.

4Setthedesktoppatterntoneutralmid-gray.Thiswillgivetheeyeaconstantneutralreference.

5 An optional accessory, which you can build yourself, is a black projectingviewing hood over themonitor. This can be cut back toward the base of thescreenasitspurposeistoshieldreflectedlightfromaboveandthesides.

Palettemonitor

Ifyouhavesufficientspace,considerasecond,smallermonitordisplayforthevariouspalettesandwindowsneededforthesoftwareapplicationyouareusing,suchasPhotoshop.Thisavoidsobscuringpartsoftheimage,andallowsyoutoruntheimagefull-screen.Analternativetothisisawider-than-standardcinemadisplay,onwhichthepalettescanbepositionedtoonesideoftheimage.

14-bitdisplay

14-bit processing, as in the Eizo range of monitors, gives 16 times moregrayscaleaccuracythan10-bitprocessing,andbecauseofthegammascale,thismeans amuch greater degree of color detail in the shadows.However, 14-bit

monitorsareconsiderablymoreexpensive.

LCDmonitors

Highbrightnessandcontrastlevels.

Noglarefromscreen.

All-digitalsignalmeansnodistortion.

Viewinganglenotanissue,asitiswithsmallerlaptopdisplays.

NoflickeraswithCRTs.

InsomecaseslesspowerconsumptionthanCRTs.

CalibratingyourMonitor

Calibratingyourmonitorisessentialifyouwanttorendercoloraccuratelyandconsistently.

Forgoodcolormanagement,usingsystemlevelcolorsoftware(introducedby

Apple in 1995 as ColorSync 2 (now ColorSync 4) and later byMicrosoft inWindows2000andXP),yourcomputerwillautomaticallygosomeofthewayto setting the displayed colors by accessing the monitor’s ICC profile. This,however,isonlyastartingpoint.

Attheveryleast,usethesystem’scalibrationsetupassistanttoworkthrough

thesettings.Thekeystepsaretoadjustthebrightnessandneutralityoftheblack,white,andmid-points;tosetthegamma(seeoppositefordefinition);andtosetthe color temperature. The resulting settings are then savedwith the name ofyourchoiceasaprofile.

The standard gamma forWindows is 2.2,which is higher (therefore darker

andmorecontrasty)thanthestandardforMacs,whichis1.8;althoughthisissettochangeaswithOS10.6,orSnowLeopard,whichhasadefaultgammaof2.2.ThismeansthatimagesoptimizedonaMacwithdefaultgamma1.8willappeardarkerandmorecontrastywhenviewedonaWindowsmachine—andtherearemany more of these than there are Macs. Conversely, images prepared on aWindowsPCwilltendtolookpalerthanexpectedwhenseenonthescreenofaMac.ThisisanissuemainlyforMacusers,andthereisadifferenceofopinion,evenamongexperts,when it comes to choosing thegamma for aMac. IfyouworkentirelywithinaMacsystem,thennative1.8gammaisclearlythewaytogo,butifyourimagesarelikelytobeviewedorreviewedonPCmonitors,thereisanargumentforworkingin2.2gamma—becausethatishowotherswillsee

thephotographs.There is also roomforchoice in thecolor temperatureof thetargetwhitepoint,whichforuseinanormaldaylitroommightbe6,500K,butinacolor-correctedstudiocouldbe5,000K.

With Macs, there is a built-in Display Calibrator Assistant, which can be

found in the System Preferences menu (under the Color tab of the Displayspanel).Windowscomputershaveneverhadadirectequivalent,althoughAdobeGammainstallsintotheControlPanelasyouinstallPhotoshopCS2andearlierversions.PhotoshopCS3andlater,however,donotdothis,althoughthird-partysolutionsareavailable.

Gamma

Gamma isameasureof the slopeorgradientof the responseofan imaging

device or medium to exposure. It is the result of plotting density against logexposure, and so is oneway of representing the contrast of themiddle usefulsection of the curve. It is therefore a good way of representing the intensityoutputofamonitorscreenrelativetotheinput.RaisingthegammaissimilarineffecttomovingthemidtonesliderinLevelstotheleft—itbrightenstheimagewithout affecting the black and white points. Lowering the gamma does theopposite—itdarkenstheimage.Anotherwayofputtingthisisthatgammaistheintensity of theoutput signal relative to the input.Theminimum input is zeroand themaximum is one, so that the default value for gamma is one—outputequals input in a linear curve. In practice, gamma can be set to between 0.45(bright,weak)and3.00 (dark, intense).Note that thehumaneye’s response togammaisasubjectiveoneofbrightnessandcontrast.DuetothedifferentwaysinwhichWindowsandMacintoshsystemsprocessthevideosignal,theirdefaultgammas are different—2.2 forWindows and 1.8 for Mac. Although this haschangedrecentlywiththeintroductionofOS10.6(SnowLeopard)whichhasadefaultgammaof2.2.

StandardMacgamma1.8

StandardWindowsandtelevisiongamma2.2

CalibrationwithWindows

InWindows,thereisnodefaultmonitorcalibrationtool.However,includedwithPhotoshopandPhotoshopElements—butno longer automatically installed—isthe Adobe Gamma tool. If installed, this will appear in your Control Panel.Simplyopenitupintheusualwayand(dependingonyourversionofWindows)selecttheOtherPanelsorClassicviewstolocateit.

CalibrationonaMac

TouseAdobeGammaonyourMac:

1OpentheSystemPreferencesdialogfromtheDock,andselect

theColortabfromtheDisplaysmenu

2Youcanthenfollowthestepsonscreen.

3You’llbeaskedtoselectatargetgamma:ifyou’reworking

exclusivelyonyourMacthenstickwiththe1.8“standard.”Ifyou’reusingOS10.6,SnowLeopard,thestandardis2.2.

Color

Indigitalphotographythereisnolongeraphysicalreference(suchasfilmoratransparency)towhichpeoplecanreferwhengaugingcoloraccuracy.

When itcomes tocolor,digital imagingallowsusundreamedof freedomto

makethescenelookjusthowweperceiveditatthetimeofshooting.Managedproperly,thefreedomthatdigitalphotographygivesyoutoadjustthecolorsand

brightnesstosuityourtasteiswonderful,anditputsthephotographerfirmlyincharge.Badlymanaged,itcanbeanightmare.

Thescenario thatallofusdread iswhen the imagehasbeenoptimizedand

workedonuntilitlooksperfectonthescreen,isthenprintedorsentforrepro,and finally appears looking terrible—such as muddy, pale, unsharp, dark,contrasty, or any of the other things that you have been assiduously trying toavoid.

Be warned that this is a bottomless issue with no single consensus among

professionals about the best procedure. This does not mean, however, that itcan’tbemanaged.Thekeyistoadaptthewayinwhichyouworktothesystemthatyouhavechosen.Thismaybeasimpleclosedloopinyourownstudioorhome,inwhichallyourphotographsareprintedonyourownprinter,oritmayinvolvesendingimagestoaclientorlabthathasitsownparticularwayofdoingthings. If you are a professional photographer, youwill often be dealingwithseveral different clients and this may simply mean that you have a set ofdifferentprocedures.Therestof thischapterwillworkcarefully throughallofthis.

Itwasessentialtokeepthesoftgreensinthismoss-coveredAngkoreanbas-reliefinordertocapturethesenseofrain,dampness,andundergrowth.

Colormanagementistheprocedureformakingsurethattheappearanceofa

photograph remains the same (orascloseaspossible)as itmoves through theworkflow.Thismeans that thepictureyou thoughtyou tookstays thatwayonyour computer screen, onother people’s computer screens, andon anyprinterthat it is sent to. You may or may not want to get heavily involved in theprocess,butthereisoneuncontestablecertaintyinallthis—thephotographeristhe only personwho knows how the colors should look.Obvious though thismaysound,itsometimesgetslostinthediscussion.Itmeans,aboveall,thatyoumustdelivertheimagesasyouwouldlikethemtoappear.Nobodyelsecandothat for you. The examples here attempt tomake this important point clearer.Even having established a good color management system and having anaccurateICCprofileforyourcamera,asdescribedonthefollowingpages,therestill remains a wide and legitimate choice. Consider for instance colortemperature. In a late-afternoon shot,would youwant awhite dress to appear

neutralwhiteorwarm?Thereisagoodcaseforeither.

Wealreadytouchedoncolorwhenitcametothecolorspacesettingsforthe

cameraandprofiling,butthefirstplacewhereyouarelikelytostartjudgingitseriouslyisonyourmonitordisplay.

SunsetovertheNile.Arangefrompaleorangetomauveissetoffagainstpalebluereflectionswhereabreezehasruffledthewaterinamutedrelationshipof

complementarycolor.

Brown,whichistechnicallyaheavilydesaturatedred,istheclassicbrokencolor,withearthyconnotations,asdemonstratedinthisshotofhennabeing

appliedtoaSudanesewoman’shand.

Colormustbecarefullymanagedthroughouttheworkflow,particularlyincaseswheretherelationshipbetweencolorsisimportant.Here,thepinkoftheman’s

robeisinalmostdirectoppositiontothehueofthegrass.

ManagingColor

If youwant the colors in your images to appear consistent as the imagespassthrough the digital workflow, from camera, through computer to printer, it’sessentialthattheyaremanaged.

Digital imaging hardware varies in how broad a range of colors each can

handleandinhoweachdistinguishcolors.Lefttothemselves,eachdevicewillpresent different color versions of your photographs. In other words, color isdevice-dependent.

Whatisneededisaprocedureforkeepingtheappearanceofcolorsthesame

from shooting to final display. The software that coordinates this is called aColorManagement System (CMS for short), and for any serious photographyyoudoneed it.Thegoodnews is thatnowadays colormanagement is at leastpartly built into the software and devices that you are likely to be using. AperfectlysoundsystemcomprisesPhotoshopColorSettings,anaccuratecameraprofile,and,ofcourse,monitorcalibration.

ACMSmapsthecolorsfromadevicewithoneparticulargamuttoanother.

Obviously this is at itsmost usefulwhen the color gamuts of the devices aresubstantially different. Printing presses (and desktop printers) have relativelysmallgamuts;certainlysmaller thanahigh-enddigitalcamera.AtypicalCMSuses a Reference Color Space that is independent of any device, and a colorengine that converts image values in and out of this space, using informationfrom the “profile” supplied by each device. The Mac OS has a particularadvantageincolormanagement—ColorSync,whichisaCMSbuilt-inatsystemlevel.

Inpractice,aCMSworkslikethis.Toconvertscreencolorstoprintercolors,

forexample, it firstconverts themonitorRGBcolorvaluestothoseinaspacethatislargeranddevice-independent,suchasL*a*b*.ItthenconvertsthesetoCMYKvaluesinthesmallercolorspaceoftheprinter,whilechangingsomeofthe colors according to the render intent. The render intent determines theprioritiesintheprocess,inwhichinevitablysomecolorswillchange.

Allofthissounds,andcanbe,complex.Inprintproductionafullknowledge

iscritical,butforseveralreasonsitisnotsomethingformostphotographerstoget too worked up about. First, the industry is gradually taking care of colormanagementinwaysthatmakeitlessnecessaryforindividualstogetinvolved.Colormanagementdependsheavilyoneachdevice (camera,monitor, scanner,printer,andsoon)havingaprofile.Cameraprofilesareknown,particularlythehigh-endmodelsthatmostprofessionalsuse.Preservetheprofileintheimagesyou save and send, and the client or repro housewill be able to dealwith it.Second,askyourselfhowmuchyouwantorneedtoimmerseyourself inprintproduction. Given all the software tools available, and the now seamlessworkflowfromcamerathroughtofinalprinting,youmaythinkyououghtto,butmany photographers think their time and energy is better focused on takingpictures. Third, the default settings for the camera will already be close tostandard, every bit as much as a normal film camera with normal film.Moreover,youcanmeasure the importantcolorvariables,meaningthatasyouedittheimagesonthecomputeryoucancheckthatneutralsareneutralandthatspecific colors have the right RGB numbers. If you use one make of digitalcamera,verylittlewillchange,andyouwillbecomeincreasinglyfamiliarwithits color characteristics. In other words, as long as you deliver an optimizedimage, with the shadows and highlights where they should be, and with nodistinct color cast (unless intentional), you will have fulfilled your normalphotographer’sduties.Whatfollowsarethebasiccoreskillstodojustthis.

Theonlyimportantqualificationisthatthemonitoriscalibrated,becausethis

is the color space in which most of the work on a photograph gets done.Calibration is important, fairly straightforward, andnothing to lose sleepover.Andthereisonegoldenrule—ifforanyreasonyoufindyourselfmakingmajor

overall changes to images from a digital camera, something is wrong. Youshouldn’thaveto,andtheproblemislikelytobeinthemonitorcalibration.

Colorprofileworkflow

A color profile workflow should ensure that every piece of color informationthatpassesthroughthecomputeristranslatedforthetargetdeviceusingprofiles.

Colormanagementcomponents

1Aworkingcolorspacethatisindependentofthedevice.

2ICCprofilesforthedevices.Thesedescribetothecomputerthecharacteristicsofeach.

3AColorManagementModule(CMM).This interprets the information in theICCprofilesandactsonit.

IMAGE EDITING PART I

RegularDownloads

Thefactthatdigitalimagesexistasahugelycomplexseriesofbinary1sand0srendersthemextremelyfragileinanumberofways.

First,astheyhaveonlyadigitalpresence,notaphysicalone,thisputsthemat

a considerable risk of being altered unintentionally, deleted, or corrupted.Theverysimplicityandimmediacyofrecordingdigitalimages,whichrevolutionizesphotographyincertainways,alsomakes themintangibleandtemporary—untiltheyareprocessedandstored.

Second, there are no unique originals in digital photography, althoughRaw

filescanbe regardedas such. Instead, thereareversions. In filmphotography,theexposureontooneframeoffilmisauniqueevent,andthatfilmbecomesthemasterimage—thissimplifiestheissueofhandling.Indigitalphotography,there

will typically be several versions of any good, useful image, includingcorrections and small, low-resolution images to sendout for easyviewing.Toavoidconfusion,itisimportanttosetthisproductiontraininmotionassoonaspossible.

ModernDSLRs,withtheirhigh-resolutionsensors,createlargeimagefiles.Nomatterhowlargethestoragecapacityofthememorycard,soonerorlateryou’ll

havetodownloadtheimagesfromthecardtoamorepermanentdevice.

Ataconvenientbreakinshooting,suchasattheendoftheday,theinitialstep

istodownloadtheimagestoaconvenientandsecurelocation.Inmostsituationsthiswillbeyourcomputer’sharddrive,eitheryourmainstudiomachineor, ifshootingonlocation,alaptop.Thetwousualmethodsarebyeitherconnectingthe camera to the computer, or by connecting just thememory card through acardreader.Ineithercase,itisimportanttochooseappropriatebrowsersoftwaretocontrolthedownloading(alsoknownasingesting).Inthefollowingexample,

thebrowserisPhotoMechanic,whichoffersanumberofusefuloptions,suchasincremental downloading (adding just the new images shot on amemory cardsince thepreviousdownload)andsequential filenaming.Thesoftwarecanalsobe set up to launch as soon as the camera or memory card is connected.Alternatively, ifyouareusingsomeoneelse’scomputer, forexample,youcancopythefilesfromthecardasyouwouldfromanyexternaldrive.

At this stage, or soon after, enter all the images into your standard filing

system.Thecamerawillalreadyhavenumberedtheimagesinitsownway,andalthoughonahigh-endcamerayoucanalter this toyourownpreferences, thefilenamesareunlikelytobeexactlywhatyouwouldlike.Changingoraddingtothe filenames while you are shooting takes time and distracts from actuallytakingpictures.Thetimeandplacetodothisisonthecomputer,andifyoudonotrenametheimagefiles,thereisariskofoverwritingthem.Itiscommontohavedifferentimagesfromdifferentshootssharingthesamefilename—andit’sarecipefordisaster.

Backing-up

Step three is toput intopracticeyourback-upregime.Dependingonhowyouplan this, you may want to make an immediate back-up, typically onto anexternal hard drive. It is important to remember that at this stage you aresecuringtheraw,uneditedimagefiles,notretouchedorcorrectedversions.Thatcomes later. The browser software should allow you to rename files, evenautomatically(althoughbeverycarefulwiththisifitdoesnotallowyoutoundoorrevert).

The procedures up to this point are the basic minimum for safety. The

workflowsequencecontinues,althoughhowmuchyouchoosetododailyisuptoyou.Ifyouareshootingprofessionallyforaclient,youwillneedtopresenttheimagesinaviewableway.Inthefirstinstance,itwouldbenormaltopreparelow-resolutionfilesinauniversalformat,suchasJPEG.Ifyouareshootingin

Rawformat,thesimplesolutionistotaketheselectedimagesthatyouwanttodeliver,andbatch-processthemtocreatesmaller-sizedcopiesinanewfolder.

Adailydownloadtoaportablecomputerprovidesanexcellentopportunitytobackupyourphotographsandtypeupnotes.Laptopscanbeverylightweight,

soareidealfortravelingphotographers.

Downloadworkflow

Thefirsttimeyourfilesareonacomputeristhefirstrealopportunityyougettoensurethatyou’reusingthecorrectfilenamesandthatanyimportantmetadataisadded.Youcanrefineeverythinglater,but thesooneryoucreatebackups,andthesooneryoutypeuptheday-to-daydetailsfromyournotebook,thesaferyourpicturesandinformationaregoingtobe.

Thebestwaytoensurethatyourphotographsarealwayssafeistofollowthe

sameprocedurereliably.ThesequencehereusesPhotoMechanic.

1Copyimagestoharddrive,eitherdirectfromthecameraor

viaacardreader.Ifyoustoreyourimagesonanalternativestoragedevicesuchasanimagebank,copyfromthisinstead.

2Itisagoodideatorenameyourfileswhenyoudownload

them.Thiswillhelpyouavoidoverwritingexistingfilesthathavebeennamedbythecameraifitnumbersyourshotsfromthesamestartingpointeachtimeyouformatamemorycard.

3MakeabackupofyourimagestoCDorDVD.

4Makeaninitialedit,rotatinganyselectedimagesthatneedit.

5Batch-processcopiesoftheseselections.Ifyou’reimporting

CameraRawfilesfromthesamesession,youcanapplyyoursettingstothewholebatch.InPhotoshop’sFileBrowser,selectAutomate>ApplyCameraRawSettings…eithertocreatesettingsforabatch,orselectoneimage

andcopythesettingsfromthat.

6Deliverthecopies.Sendcopiestoyourclientortoasecure

server.

IntermediateStorage

One thing that hasn’t changed with the advent of digital photography is theplanningrequiredwhenshootingonlocationformorethanadayortwo.

Althoughyounolongerhavetoestimatethequantityoffilmyouwillneed,or

plantoreplenishstockatdealersalongtheway,youdohavetoplanforstoringtheimagesindigitalmedia;morethanthat,youneedtohaveasensiblyworkedout“productionflow”of image transfers thatwillkeeppacewith thewayyoushoot.

Thenumbersareeasytocalculate,andstartwiththefilesizeofoneofyour

typical image. Memory cards are relatively expensive storage media, and thefasteryoucantransfertheimagestolessexpensivemedia,thebetter.Themostefficient strategy for long-term shooting (over a period of time, such aswhentraveling) is to have sufficient memory cards to be able to continue shootinguntilyoucanemptythemconvenientlyontoalargerharddrive.Thequantitiesdependonyourindividualwayofshootingandonthekindofsubjectsthatyouexpecttocomeacrossonatrip—paradesandspecialevents,forinstance,tendtoconsumeimagesfaster.

Thisshines thespotlightclearlyonportable long-termstorage,and themost

immediatelyobviousanswer is tocarrya laptopanddownloadimagesonto its

harddrivewithadditionalsmallexternalharddrives.Foradditionalsafety,addextralevelsofbackupbytransferringfilesfromthelaptopalsoto,forinstance,aniPodandcellphone.Analternativeisastandaloneportablestorageunitthatfeatures a small, typically 2½–in, hard drive and a port that accepts memorycardsdirectly.Thereareseveralmodelsavailable,withcapacitiesupto160GB,thatcanbeACorbattery-powered.ThesePDA-sizeddevices,whichweigh intheregionofjustafewounces,areconvenientenougheventoconsidercarryingin a shoulder bag asyou shoot.All of this bypasses the computer completely.This is an improving technology, somonitor the latest developments: the firstgenerationofportablestoragedevicesoftendidnotevenhaveaviewingscreen.

For short-term back-up protection, it’s also sensible to aim to transfer the

images,oratleastthoseselected,ontonon-digitalmedia,ofwhichthecheapestandmostpracticalareCD-ROMsand,forlargerquantities,DVDs.ThismakesalaptopwithCD-orDVD-burningabilityuseful.

In digitally developed countries, many film-processing labs and camera

dealers offer inexpensive copying frommemory cards ontoCD-ROMs. If youcheckinadvancethatthisserviceisavailableatyourdestination, itsavestimeandeffortandremovestheneedtocarryyourownstoragemedia.Eveninlesssophisticated places, if you have a card reader you could look for an Internetcafé or computer center, or even the business center of a hotel, thatwould bewillingtodownloadyourimagesandthenburnthemforyouontoaCD-ROMorevenaDVD.

CreatingCDsorDVDs

More recent computers, whether Mac or Windows PCs are now capable ofburning CDs without recourse to additional software. The process is one ofsimpledraganddrop, thoughit isworthremembering thatCD-Romscanonlybewrittentoonce,sotrytouseasmuchspaceaspossible.

Portableharddrives

Thereareanumberofportableharddrivesavailablewithapreviewscreen.Theinput port accepts any of the standard memory-card formats, while USB orFirewireoutputallowstheimagestobedownloadedtoacomputerattheendofa trip. Indeed,manyportable hard drives can be used for image storage, evenmusicplayerssuchastheiPod.

EPSONP-7000

Witha4-inchLCDscreenanda160GBharddisk,theP-7000provides

excellentstorageandplayback.ImagescanbecopieddirectlyfromtheCForSDcardslotstotheharddisk,makingthisahandytravelingcompanion.

BelkinMediaReaderforiPod

TheiPodisubiquitousthesedays,andifyouhaveone,thereisnoneedtoinvestinaportableharddrive.ThisBelkinadapterallowsyoutobackupimagestoit

viaaUSBsocket.SomeiPods,however,arenotcompatible.

ImageBrowsers

Image browsers are an important and integral part of the digital softwareworkflow. They allow you to organize images into folders, give the filesmeaningfulnames,andviewthem.

Browsersoftware isnormallysuppliedfreeby thecameramanufacturer,but

maynotbeasusefulandwell-designedasstandalonesoftwaredesignedtoworkwithallstandardcamerasandformats.WiththeincreasinguseofRawshooting,itisimportantthatthebrowseryouuseiscapableofreadingthismanufacturer-specific file format, and that the software designers are committed to keepingpacewithupdatesandnewcameramodels.

Innormalshootingtheimagesaredownloadedfromthememorycardtothe

computerthroughaninterfacecablethatisnormallyUSBorFireWire.Thiscanbedoneeitherdirectlyfromaportonthecamera,orbyremovingthecardandinserting it in a card readerwhich is plugged into the computer. The transfersoftware,whichiseitherpartofthebrowserorlinkedtoit,allowsyoutoselectwhich images to transfer, to choose transfer options, specify the destinationfolder,andchoosehowtheimagesaretobenumberedornamed.Takecaretoavoid overwriting image fileswith the same name, although the softwarewillprobably anticipate this and either give a warning or else assign differentfilenames.Somecamerasareequippedwithadedicatedtransferbutton.

Namingandnumbering

Even if you accept the defaultmethod, your imageswill be given a name ornumberidentificationas theyaretransferred.Typically, thereare threeparts tothis—aprefix,an identifier,andasuffix, the latter separatedbyaperiod.Youmaychoose toassignapermanent filename that fits intoyour long-termfiling

systemasyoudownload,ordealwiththislaterwhenyouhavemoretime.Inthelattercase,thebrowserhasanautomaticbatch-renamingprogram.

Filenamingconventions

Windows

AlthoughinthepastWindowsallowedonly8-letterfilenames,thesedaysthereis just one practical restriction on file naming: never use a period (.) sinceWindows traditionally uses these as the divider between the filename andextension (for example name.jpg is a JPEG file). InWindowsXP,Vista, andWindows 7, where long filenames are supported, themaximum length is 255characters.

Macintosh

Themaximumlengthfor legacysystems(beforeOSX)is31characters.Morenon-alphanumeric characters are allowed than for Windows (for example theperiod),butifimagesaretobeusedcross-platformortransmittedbye-mailorFTP,itisbettertosticktotheconventionsmentionedabove.

Browsing

A browser such as Adobe Bridge (included with Photoshop), or externalsoftware such as iView Media Pro, allows you to view images, and makechangestofileinformation,includingthemetadata.

Rotatingimages

Somecamerasareabletosensewhentheyhavebeenturnedtoshootaverticallycomposed image, and embed this data so that the browser can automaticallyrotate the image. Otherwise, you can identify and rotate vertical imagesmanually in thebrowser.There isa slight riskof imagedegradation ifyoudothis with JPEGs, but some browsers compensate for this by rotating JPEGswithout decompressing them first. Check the browser manual for therecommendedprocedure.

Theimportanceofmetadata

Metadataisembeddedfileinformation,someaddedbythecamera,somebytheuser.Itincludesthefollowing:

FileProperties

Characteristicsthatincludesize,creation,andmodificationdates.

CameraData(EXIF)

Addedbythecamera,EXIFinformationincludesthecamerasettingsthatwereusedwhen the imagewas taken, suchas the time,date, ISO, shutter, aperture,and other extended details. EXIF (Exchangeable Image File) format is anindustrystandarddevelopedbyJEIDA(JapanElectronicIndustryDevelopmentAssociation).

GPS

Some digital cameras have GPS (Global Positioning System) technology thatallowsthelocationofaphotographtoberecorded.

EditHistory

Alogofchangesmadetoanimage.

IPTC

Theonly user-editablemetadata, this allowsyou to add caption and copyrightinformationtoanimage.

ViewingtheEXIFcameradataintheNikonbrowser.

Databases

Databasesdifferfrombrowsersinthatalthoughit’spossibletoviewimageswithdatabase software, their primary function is to help you manage a largecollectionofphotographs.

Inorder tomake themostefficientuseofadatabase,youwillneed toplan

from the start exactly how you allocate file names. There are many possibleways,butwhateveryouchooseitmustbelogicalandalloweasysearches.Mostlarge imagedatabasesuse anumerical identifier, butyoucan adda secondarydescription. Searching is normally performed on keywords. There may beoccasionswhenyouneedtosavedifferentversionsofanimage,andthesewillneedeitheradifferentsuffix(forinstance,.jpgand.tififyousaveanimageintwo file formats)or someextra identifier.For instance,youmaywant tokeepboth an unsharpened and sharpened version, in which case you could usesomething similar to the following: “15624_flamingo” and“15624_flamingo_usm”. Check how your database handles attempts atduplicating filenames, as it is essential to avoid overwriting original imagesunintentionally.Workflow softwaremay avoid the need bymeans of its non-destructiveeditingfeatures.

Databasetoolscanrenameyourfilesinbatches,andaddserialnumbers.

ExpressionMedia’sthumbnailviewisanefficientbrowser.

Thereareseveralcontenders,andtheonefeaturedhere isExpressionMedia

(formerly known as iView MediaPro), not least because I use it. There is aconsiderableamountofworkinvolvedinusingadatabase,andit iscontinuingwork, so selecting one demands some thought. Unless you opt for workflowsoftwarethat incorporatesdatabasefunctions,yourdatabaseshouldbethecoreof your picture-managing operations. Themore it allows you to do, includingselection, captioning,moving and copying files, and so on, themore useful itwillbe.

One decision to make early is whether to use the database for

importing/uploading/ingesting images from the camera or memory card, orwhethertodothiswithabrowser.Theadvantageofusingthedatabaseisthatitkeepsonemoreoperationunderasingleroof.Thepossibleadvantageofusingabrowsertodothisisthatthebrowsermaybequickerandmoreflexible.

EditingEXIFdata

EditingEXIFdata

EXIF data is embedded in the image by the camera, and includes time, date,ISO,shutter,aperture,andmore.Thereislimitedsoftwareavailableforalteringit, because in principle this is useful information that other programs can use,suchasdatabases,noisereductionsoftware,andothersthatrelyonknowingtheprecise settings.Nevertheless, there are reasons forwanting tomake changes,andthemostcommonistocorrectthetimeanddate—itisalltooeasytoforgetto change the camera time and date settingswhen crossing time zones. Somedatabasespermitlimitedadjustments;iViewMediaPro,forexample,hasatimeand date change function. Otherwise, use command-line instructions in aspecializedprogramsuchasEXIFutils,butusewithextremecare,aschangesarenon-reversible.

NewWorkflowSoftware

Recentinnovationsinworkflowsoftwarehaveseentheemergenceofanumberofprograms thatattempt tooffera“one-stopshop”solution todigital imagingworkflow.

Examples of such software includedAdobe’s Lightroom,Apple’sAperture,

andPhaseOne’sCaptureOne.

Whattheyallaimtoreplaceistheworkflowmodelthatreliesonabrowserto

download,animagedatabasetoorganize,andPhotoshoptodopost-production.The advantage of one-stop software is speed and neatness, and the ability toconcentrateonessentialsratherthanpickthroughthemanyfeaturesofthelatestPhotoshop that are of little value to photography. Against this, they requirelearning a new workflow system, creating a resistance among photographerswhohaveinvestedyearsinlearningthe“traditional”photographer’sworkflow.

Lightroom

Lightroom’sDevelopmodeoffersallthesamefeaturesasAdobeCameraRaw,whichisnoaccident.Edited,theimagedoesnotaffecttheoriginalfile;insteadalistofchangesiskeptinLightroom’sdatabase.Whentheimageisexportedthechangescanbeimplemented,orsavedasa“sidecar”filewhichthenext

applicationcanusetoapplythechanges.Thisiswhytherearefewpixeledits,asidefromsomecloning(wheresourceandtargetpointscanbereferenced).

In order to streamline theworkflow and create an attractive visual interface

andexperienceforusers,themajorworkflowsoftwareprogramshave,tosomeextent,buriedtheworkingsofthepost-productiontoolsthataremoretransparentin Photoshop, and there are divergent views onwhether or not this is a goodthing.Forphotographerswith longexperienceofPhotoshopandwhoprefer tostay firmly in control of image quality, there may be no clear advantage inchangingtheirtriedandtruesystem,butforphotographerswhoareeithernewtodigital imaging, orwhoprefer to limit their involvement to the essentials, this

kindofsoftwaremaybeideal.

Themaincontenders in thissoftwaremarketvary in theirapproach,andare

alsoconstantlyupgradingandevolving,asthisisarelativelynewareathatstillcallsforuserfeedback.Threefeaturesthatallhaveincommon,however,areaRaw-focused approach, strong comparison and selection tools, and non-destructiveprocessing.

Assuming thatmostoriginal fileswillbe inaRawformat is sensible,given

the target audience of serious amateurs and professionals; compare-and-selectprocedures are essential for a program that promises to handle a large shootwhichmust eventually bewhittled down to a few selects; and non-destructiveprocessing,whilenotbreathtakinglynew,isonewayofpreservingtheoriginalfiles while allowing them to be processed. Key technical issues still beingaddressedareperformancespeedforvariousoperations,openarchitecture,andthepossibilityofthird-partyplug-insinthefuture.Asitstands,thesecanbeveryefficient and intuitive tools, if for no more than the ability to scan quicklythrough images at full-screen, identify the best, and begin that work withoutleavingtheprogram.Thefullrangeoftools,allofwhicharenon-destructiveandlightonstorageconsumption,isahugebonus.

A fewmorewords on non-destructive processing—in principle, this simply

means keeping the various steps in post-production, such as setting black andwhitepoints,curvecorrections,sharpening,andsoon,asseparate instructions,and there are other ways of doing this. It happens in the camera, of course,wheneveryoushootRaw.RawconverterssuchasCameraRawsavethesettingslastapplied toan imageasasidecarfile,whilePhotoshopCS3andlaterhasaSmartFiltersfeaturethatcanbeappliedtoaSmartObjectlayer.

Workflow

ImportImages

Workflowsoftwarewillgenerallyallowawiderangeofoptionswhenimportingimages, includingwhether you create a copy of the file,move it into a folderorganized by the application, or simply reference it. You can also add yourcopyrightpresetsandanykeywordsforthebatchofimagesyouareimporting.

Organize

Aswithdatabaseapplications,a fully featuredbrowseviewallowsyou tosortthroughyourimages,addandsearchonkeywords,performrenamingoperationson your files, and so on. Although renaming is permanent, most informationaboutyourimagesisstoredinthedatabaseratherthanalteringthefiles.

Review,rank,andselect

Viewing images full-screen and adding ratings is a quickway to isolate goodshots.

Process

Thisisperhapsthekeydifferentiatorbetweenworkflowsoftwareanddatabases:that it is posssible to enter into an editmode andmake changes to the image,bothwholesalefixesandsomelocalrepairs.

Distribute

Lightroom,forexample,cangenerateHTMLorFlashwebpages,slideshows,andofcoursevariousprintsincludingcontactsheets.

Re-Order

Itisalwayspossibletogotothebrowserandre-arrangeorsortthedatabase.

CaptionsandKeywords

An important part of managing your images is using captions and keywords.Thesecanbeaddedatanystageof theworkflow,andhelp tomakeaccessingandretrievingimagesquickandeasy.

The standard for doing this is called IPTC (International Press

TelecommunicationsCouncil)anditincludesentriesfordescriptions,keywords,categories, credits, and origins. This is important not only for cataloging, butalsoforsellingreproductionrightsinimages.Captioningimagesmayseemlikeachore,butnowthatstocksalesplaysuchanimportantpartinthebusinessofphotography,itisessential.Notingthekeydetailsofwhatyoushotisusefulforyour own records, but the real reason is so that other people can find yourimages. This is very much a feature of being digital and online because thedescriptions that are easily attached to the image file can be used by searchengines.Inpre-digitaldays,therewereonlytwowaysforapictureresearcherorartdirectortofindaspecificphotograph:callupstocklibrariesandask,orlookattheprintedcatalogsfromthesamelibraries.Nowstock-agencywebsitesallowthepeoplewhowantpictures tosearchfor themselves,andunderstandinghowthathappensinpracticehelpstosellimages.

Captionssellphotographs.Atleast, theysellcontent-basedphotographs,and

themorespecializedthesubjectmatter,themoreimportantitistoknowexactlywhatyoushot.Thebesttimetodothisisonthespot,whileyoucanstillask,andbeforeyouforget.Anotebookortaperecorderaretheeasiestmeans;inputtingdirectly into the camera seems efficient, but takes longer.Aspart of a normalworkflow, captioning fits most easily into the image editing, either before or

after optimization. A successful caption is informative, focused, and succinct,and the first skill is to identify the salient facts and thenprioritize them.Withstock images, the aim of the caption is to present all relevant information toother professionals rather than general readers,while the keywords add to thesearchable information. All this information can be extracted by image-management programs and other databases. The time to enter the captioninformationisasearlyaspossibleintheinevitablechainofimageversionsandcopies. Itmaybeworthmaintainingamastercaption list inaword-processingprogramasareminderofwhichimageshavealreadybeencaptionedandalsoasa source for cutting and pasting. Several images may share the same basicinformation,oratleastsomeofit—youcouldthencopypartsofentriesfromthemasterlistintoPhotoshop’sFileInfoforeachnewimage.Alternatively,savethemetadatawhere it can be retrieved from another image’sFile Info dialog (seeMetadatainPhotoshop,below).

TheFiveWs

Who

Name if famous, newsworthy, or relevant. Ethnic origin. Job or position ifrelevant.Genderifababy.

What

Decidefirstwhetheractionorobjectisthesubject(considerwhatmotivatedyoutotakethepicture).Ifaction,describeitinfirstsentence.Ifobject,givename(ifaknownbuilding,landmark,geographicalfeature),description,andifaplantoranimal,givethescientificname.Insomecases,theconceptwillbeappropriate—that is, an idea that you were trying to express (such as harmony, love,security).

Where

Location as precisely as possible, ideally with a hierarchy (e.g. Montmartre,Paris,France).

When

Date.

Why

If the action isnot immediatelyobvious to aviewer, explain it (usually in thesecondsentence).

Creatingkeywords

• Keywordssupplementthecaptionforthepurposeofsearching.

• Thereisnoneedtorepeatawordthatisalreadyinthecaption/description.

• Toomanykeywordsisasbadastoofew.Aimfornomorethan10.

• Think of what words your target audience is likely to use (for example, anaturalhistorypictureresearchermayusethescientificname).

• Includedifferentspellingsandusages(forexamplegasoline/petrol).

• Includethepluralunlessitsimplyhasan“s”added.

MetadatainPhotoshop

Metadata can be viewed and edited either in theMetadata palette of the FileBrowser or in the various windows of File Info (File > File Info...). Havingentered the IPTC information (captionunderDescription, keywords, copyrightinformation,andsoon)youcansavethisforfutureuseinother,similarimages:either save as a Metadata Template or as an XMP (Extensible MetadataPlatform)filefromtheAdvancedtaboftheFileInfowindowinPhotoshop.

Keywords

Keywords

Being able to retrieve images quickly and easily is the core function of anyimagedatabase.Asimagesaccumulateinthedatabase,itbecomesincreasinglydifficultevenforthepersonwhotookthemtorememberthedetails.Ifyouwantotherpeopletobeabletosearchthroughyourlibraryofpictures,forinstanceifyouaresellingthemasstockphotography,youwillcertainlyhavetoanticipatehowtheymightsearch.Thesoftwareissuesarehighlytechnical,butcommontoall is the concept of keywords.These arewords describing some aspect of animage; when someone enters a word in the search box of the database, theprogramwilllookforimagesthathavethesamewordattached.Themorevariedyet relevant the set of keywords attached to each photograph, the better thechanceofmatchingthesearcher’srequest.Thetrickisinimaginingwhatotherpeople might look for, beyond the obvious description. Where there iscompetition,itisofgreatbenefittohavespentjustalittlemoretimeandenergyaddingkeywordsthanyourcompetitor,thoughobviouslyit’simportantthatyourdatabasedoesn’t“crywolf”byusingkeywordsthatdon’tdescribethepicture.

Inthisdatabase,thefieldstocompleteare:ShortCaption,LongCaption,andalistofKeywords.Theshortcaption,“DashimakiTamango,aJapaneseeggroll”doesnottreadonthetoesoftheKeywordlist:cooking,eggs,omelette,cuisine,

food,yellow.

Long-termStorage

Unlike film and transparencies, which have a physical fragility and aresusceptible to being scratched or suffering some other type of damage, digitalfilesinonesensearemuchmorerobust.

However,asweknowdigitalfilescaneasilybecomecorruptorevenlost,so

it’simportanttokeepthemsafe.

Yourcomputer’sharddrive,nomatterhowlarge,willeventuallyfillup,and

forthisreasonaloneitisimportanttomovethefilestoothermedia.Moreover,havingabackup isapartofgoodcomputerhousekeeping—remember that thehigh-volumesolution formostpeople isanexternalhard-drive,andpreferablymorethanone.Mirroredharddrives,meaningonecarryinganexactcopyoftheother,arestandard insurance. Inaddition,dependingon thevolumeyoushoot,yet anotherbackuponaDVDhas theadvantageofbeingadifferentmedium,and non-magnetic. DVDs are also universal and compatible. Most computerscomefittedwithaCD-writeratleast,andsomewithaDVD-writer.Thevariousflavors, as they are known, are described here. Backup policy involves twoactions:makeanidenticalcopyofeverythingyoustore,andkeepitinadifferentphysicallocation.

Therearemanybackupprogramsavailable.The simplest,but least efficient

methodistosimplycopyallthefilesontothedestination.Truebackupsoftwareallows you to perform incremental additions, making it unnecessary to copyexistingfilesoveragain.Asageneralrule,backupsoftwarethatdevotesalotofenergy to making the interface comfortable and idiot-proof performs moreslowlythanstripped-down,leanerprograms.

Backuptotape

Manyprofessionalphotographers,whohaveaverylargenumberofimages,relyon traditional backup technology—tape. Its two considerable advantages arecapacity(tensandhundredsofgigabytes,eventerabyteswithsomesystems)andcost.Securityand longevityarehigh, andwhile there is constantdevelopmentgoing on, and therefore many different formats, this is such a universallyaccepted back-upmethod that itwill be around for a very long time. FormatsincludeADR,DLT,AIT,SAIT,andDAT.

TapeDrive

WritingDVDs

DVD,oftenthoughtofasdigitalvideodiscbutmorecorrectlyknownasdigitalversatile disc, is a development of theCD,with a seven-fold increase in datacapacityandabasictransferrateofaboutninetimesthatofCD.Thetrackpitch(distancebetweeneach)islessthanhalfthatofCD,thepitsaremuchsmaller,thelaserwavelengthissmaller,datacanbeburnedtoandreadfrommorethanone layer (by changing the focus of the laser) and from both sides.With thesame 5-in (12cm) diameter, 1.2mm thick dimensions as CD, DVD has thefollowingcapacities:

• DVD-5-4.7GBsingle-sided,single-layereddisc.

• DVD-9-8.5GBsingle-sided,double-layereddisc.

• DVD-10-9.4GBdual-sided,single-layereddisc.

• DVD-18-17GBdual-sided,dual-layereddisc.

TherearefiverecordableversionsofDVD:

DVD-RAM

The first rewritable DVD format, DVD-RAM uses phase-change technologysimilartothatinCD-R.OfalltheDVDformatsthisistheleastcompatiblewithdifferentplayers.Ithassomedistinctadvantagesintermsofrewritinganddatarecording,however,sinceitdoesnotneedtorecordalead-inandlead-outeachtimethediscisused.

DVD-RandDVD-RW

SimilartoCD-R,DVD-R(or,DVD-Recordable)iswrite-once.Recordingtakesplace on a dye layer that is permanently altered by a highly focused red laserbeam.AswithCD-R,therearethreeareas:lead-in,userdata,andlead-out.Also,aswithCD-RandCD-RW, thewrite-once -R format is compatiblewithmoreDVD read-only drives than its -RW counterpart. (This is the format used byApple’sbuilt-inDVDwriter,the“Superdrive.”)

DVD+RandDVD+RW

ThisthirdrewritableDVDformathasthehighestcompatibility.LikeDVD-Ritcomes in write-once and rewritable flavors with varying degrees ofcompatibility.Somedrives cannowwrite toboth+Rand -R formats, and aretypicallydesignated±R. Ifyou’rebuyingaDVDwriter, this isagoodwayofhedgingyourbets.Atthemoment,onlyDVD+Rsupportsdual-layerburning.

NewerDVDwriters,suchasthisonefromSony,arecapableofwritingdual-layerdiscs.The8.5GBdiscsarefullycompatiblewiththeDVD9standard.

RAID

RAIDstandsforRedundantArrayofInexpensive(orIndependent)Disks,andisahardware-plus-softwaretechnologydesignedforhigh-storagesafety.ARAIDdeviceisastackofharddrives(typicallyfourorfive)thatfunctionasasingleunit. Depending on the RAID level you choose to implement, the device canstore files in such a way that if one disk crashes, all the information can berebuiltfromtheremainingdrives.ThesafertheRAIDlevelchosen,thelessthetotal capacity. Individual drives are hot-swappable,meaning that you can pullthemoutsafelywhilethedeviceisconnectedandrunning.

Fileformatsandcompression

While there are a number of file formats inwhich you can save images after

optimization—see the listavailable inPhotoshop’sFormatdrop-downmenuinthe Save As... dialog—there is little reason for photographic images to straybeyondthetwomostwidelyrecognized:TIFFandJPEG.Universalreadabilityisimportantiftheimagesarelikelytobeseenandusedbyotherpeople,andifyou want to open them in different applications. TIFF offers a losslesscompressionmethod,LZW,and thiscan typicallyreduce thefilesizebymorethan half. This is for 8-bit images; it does little for 16-bit. JPEG is both fileformatandcompressionsystem,andidealfortransmission.Youcanchoosethedegree of compression in the dialog box as you save, but beware of savingJPEGsmorethanonce—thissimplymultipliestheartifacting.

BasicOptimization

Optimizationissimpyatermforimprovingthelookofanimageandpreparingit for final viewing. In itsmost basic sense, optimizing an image is away ofgettingtheimagetolookasyouthinkitshould.

Thisseeminglystraightforwardideahidestheissueofhowyoudefinethebestappearance,andinpracticethisisacombinationofobjectivetechnicalstandardsandthesubjectiveonesofyourpersonalpreference.Asthepersonwhosawthesceneandchose to take thephotograph,onlyyouare fullyqualified todecidewhattheoptimalbrightness,contrast,andcolorshouldbe,andforthisreasonitis always best to perform these adjustments as soon as possible, while yourmemoryisfresh.

The key here is the sequence—the order in which you make the several

differentadjustmentstotheimage.Theaimistoavoidmakingachangethatwilllater be changed again, as would happen for instance if you first altered aspecifichueandthenmadeaglobalcolorchange.Themostlogicalapproachis

towork fromglobal corrections to selective, and the following four stages dothis:

1Balance theoverallcolor,eliminatinganyunwantedcast.Either identify thisbias by eye and use any of the usual tools (Color Balance sliders, individualchannels inLevelsorCurves),oruseaGrayPoint“dropper”onany tone thatyouthinkshouldbeneutral.

2Settheblackandwhitepoints.ThesimplestwayistocloseuptheendsofthehistograminLevels.Otherwise,useBlackPointandWhitePoint“droppers”onthedarkestandbrightestpartsoftheimage,respectively.

3 Adjust brightness, contrast, and saturation overall. Curves gives excellentcontroloverbrightnessandcontrast,whilesaturationismosteasilyadjustedintheHue/Saturation(HSB)dialog.

4Adjustindividualcolorranges,forinstancebyusingoneofthehuerangesinHSB.

Inmanycases,optimizationinvolvesmakingsubjectivejudgementsastothefinalappearanceoftheimage.BothoftheseshotsofelephantsunderatreeintheAfricansavannahareperfectlyvalid.Thelightertopimageperhapsevokesmorestronglyasenseofbrightheat,whilethelowerimageplaysmoreon

contrastandcolor.

Quickoptimization

It is possible to make an independent, objective adjustment that traces andeliminates a color cast, closesup the endsof thehistogram tomake the rangefromblack(0) towhite (255),andperformsapre-setsaturation.This takesnoaccountofthecontentoftheimage,butisausefulstartingpointasanunbiasedsuggestionofhowtheimagemightbeimproved.Oneofthereasonsitworkssowellhastodowiththepsychologyofperception—inaside-by-sidecomparison,mostpeoplepreferbrighter,richer,crisperversionsofanimage.InPhotoshop,tools to consider are those in the Image>Adjustments>menu, such asAutoLevelsandShadows/Highlights.Therearealsothird-partyapplicationsthatcanhelp,suchasI-Tricks2,astandalonecolor-repairprogram.

Subjectiveassessment

The process of optimizing for color has one serious built-in flaw. It tacitlyassumesthateveryimagedeservesthesamebasicstandardsofbrightness,afullcontrast range, neutral grays, and so on. Most of the time this is true, and“automaticoptimization”nearlyalways looks instinctivelybetter.Yet thismaynotsuitthepurposeoftheshot.Forexample,ifpartoftheappealofalandscapeisitslimitedrangeofmutedcolorsandsoftness,thereisnopointinclosingupthe Levels to give it a range from black to white. The very first step inoptimizing any image is to assess it from a creative viewpoint.Whatwas theeffectyouwereaimingforwhenyoushot?Willitsuittheimagetobeotherthannormal?

Basicoptimizingprocedure

The iCorrect EditLab provides an excellent example of an ordered optimizingworkflow. The approach can just as easily be achieved in other software;balancing the overall color, then the levels histogram, before making morepersonaladjustmentstobrightness,contrast,andindividualtones.

1Correcttheoverallcolorbalancebysettinganeutral.

2Settheblackandwhitepoints.

3Adjustbrightness,contrast,andsaturation.

4Correctspecificcolors(hues)individually.

AdvancedOptimization

Every image requires its own level of optimization; some will simply needtweakingintermsof,forexample,contrast,othersmayrequirealotmorework.

Even ifyou thinkyouhaveaduty todoeverythingpossible, in the realworldtheremaysimplynotbeenoughtimetoworkoneveryphotograph.Inanycase,optimizing is subject to the law of diminishing returns—lengthy tweaking ofdetails may not have a significant impact. Nevertheless, the recommendedprocedureforafulloptimizationisasdescribedhere.Remember,however,thatthisisnotcastinstone,butjustanexampleofonereliablesequence.

ARawadjustment

Foranyoneseriousaboutgoodimagequality,thefirststepistoshootRaw.Thelatest Photoshop Raw adjustment window offers an exceptional range ofcontrols,whereitispossibletodoalmostallofyourimage-optimizingwork.

BAssignprofile

This isbestseenasanalternative toRawadjustment,and it isnotpractical tomakefulluseofboth.Ifcolorprecisionisimportant,youmaywanttoadjustthetonalrangeintheRawdialog,andthenassignapreparedprofile.

CLevels

Again,ifyouhavemadegooduseofRawadjustment,inparticulartheExposure

andShadowssliders,goingtoLevelsmaynotbenecessaryotherthantocheckthe histogram.Otherwise, the key procedure in Levels is to set the black andwhite points. Any adjustments to the tones between these points, however, isbetterlefttotheCurvesdialog.Movingthemidpointslideraltersthebrightnessaroundtheexactmidtoneonly,whileCurvesallowsyoutheflexibilityofbiasingthelighteningordarkeningtowardtheshadowsorhighlights.

DCurves

Thishaslongbeentheprecisiontoolfortonaladjustments,Nevertheless,itnowhastwostrongcompetitorsinPhotoshop—oneistheRawadjustmentdialog(A),andtheotheristhenewShadows/Highlightsdialog(E).

EShadows/Highlights

This extremely useful control is slider-based in operation, designed forphotographs,andactuallyexceedstheabilityofCurvestomanipulatecontrastinthemidtones.Because of its uniquemethod ofworking, this is almost alwaysworthlookingatbeforefinalizinganimage.

FHue/Saturation

WhilesaturationcanbemanipulatedinCurves,thesimplestcontrolforitistheHue/Saturationdialog.Onceagain,however,Rawadjustmentalsoallowsgreatcontroloverhueandsaturation,andmaymakethisstepunnecessary.

GDistortion,correctionandcropping

Distortionmayoccurbecauseof tilting the camera in a situation that calls forvertical verticals, or through over-enthusiastic use of an extreme wide-anglelens, or because of lens barreling or pincushion distortion. Correction usuallyleavessomegaps thatneedcropping,so that ifyouplan tocrop the imageforcompositional reasons, it is best to run these two operations together.Photoshop’sdistortion-correctiontoolsareeitherthoseunderEdit>Transform,ortheLensCorrectionfilter,andtherearemanythird-partyplug-insfordealingwithlensdistortionofthebarrelingandpi-cushionvarieties.

HRetouch

Finally, and there is little point in doing this before the above procedures,removeartifactswith theHealingorCloneStamp tools.Themainculprits aredust particles on the sensor, but you might then decide to move on to moreelaborateimage-editing,suchasremovingpowerlinesfromalandscape,orskinblemishesonaportrait.

OptimizationTricksandTips

Image-editingtools,particularlythosesuchasPhotoshop,PaintShopPro,andsoon,areimmenselypowerfulprogramsthatofferanumberofwaysofachievingalmostidenticalresults.

Forthisreasonthestepsoutlinedonthepreviouspagesarenomorethanmy

recommendation. This is partly because there are so many ways of makingsimilarcorrections,butalsobecauseanyevaluationofaphotographisultimatelysubjectiveandpartofthecreativeprocess.Alliedtothisistheconceptof“tipsand tricks,” which in other circumstances would just be sloppymethodology.Yet in optimization and image-editing generally, tips and tricks are—strangethoughitmayseem—apartofthemethodology.Herearesomekeyones.

Editathighbit-depth

Despitethefactthatnormal8-bitcolorcandisplay16,777,216separatecolorsinan image—wellbeyondtheeye’sability todiscriminate—anymajorchange to

thecontrast,brightness,orcolors, suchasyoumightmakewith theCurvesorLevelstoolswilldestroysomeoftheseasitshiftscertainpixelvalues.Thetell-tale sign is in thehistogram—afteranadjustment therewill typicallybewhiteline gaps and black spikes above, instead of a smoothly curved, solid-blackmass. The way to avoid this is to edit in 16-bit. It’s double the file size andoverkill for a final image, but there are sufficient color steps (well over 281trillionofthem)toaccommodateanychanges.IfyoushootinRaw,Photoshopwillautomaticallyconverttheimageinto16-bit.Otherwise,ifyouhavean8-bitimage,it isstillworthwhileconvertingit to16-bitforediting.Butinthiscase,converttoLabmodeandedittheLightnesschannelfortheleastdamage.

Before

After(8-bit)

After(16-bit)

UsePhotoshopprofiles

IfpartofyourworkflowincludesmanagingcolorinPhotoshop,youwillneedtocalibrateyourmonitor,usingeitherthevisualmethodorbyusingacolorimeter.ThefirsttimeyoulaunchPhotoshopafterinstalling,you’reasked“Doyouwishtocutomize thecolor settings?”Thedefault setting isWebGraphics,which isdesigned tomaintaincolorgraphicsconsistentlyon screen. Itmaybe thatyoudon’t need to alter this at all; however, if you’re planning another kind ofworkflow, click Yes to be taken to the Color Settings dialog. If you’re notinstallingPhotoshopforthefirsttime,youcanaccessthedialogviaEdit>ColorSettings… (or on older Mac versions via the Photoshop menu). In order to

maintain consistency, make sure that you use the same settings in any othercolor-managed applications that you use. Colors might also seem different innon-colormanagedsoftware.

GotoColorSettingsandmakesure that thehighlighted fieldsareasshown

here. Adobe RGB (1998) is in any case the working space of choice forphotographs. Under Color Management Policy, for RGB choose Convert toWorking RGB; this ensures that images always appear in this standard colorspace.Thetwooptionsatthebottomofthewindowgiveyoutheopportunitytodiscardunwantedprofilesandtoassigntheoneofyourchoice.

Evaluatingacolorchart

If getting accurate color is paramount, photograph a test that includes a colorchart (suchas theGretagMacbethColorCheckerbelow). Ideally,do itonceforanygivenlightingsituation.Foreasyreference,cropintothechartandsavethisimageasacheckfile.ItsappearanceinPhotoshopshouldbeasfollows;ifnot,

usetheRaweditorsothatitdoes—andnotethesettings.

1Thewhitesquareshouldbe250-245andnohigherinallchannels.

2Theblacksquare(darkestneutral)shouldbe5andnolowerinallchannels.

3Youcandistinguishalltheneutralsfromeachother.

4NoRGBvaluesinanysquarearelowerthan5orhigherthan250.

5TheRGBvaluesintheneutralsquaresarewithin5pointsofeachother(e.g.126,130,127,not124,132,121).

IMAGE EDITING PART II

ShootingRaw

Apartfromthefactthatitrequiresadditionalpost-productionworkthatwilltakealittlemoretime,shootingintheRawformatprovidesmanybenefits.

Thesimplereasonforthisisthatthedataandsettingsarestoredseparatelyon

capture,meaning that you have complete access to the original, “raw”data inyour image-editing program.Moreover, this image information remains at themaximumbit-depthofwhich thesensor iscapable (typically,12-bit,14-bit,or16-bit).Ifyouhaveanyneedtooptimizeoraltertheimage,Rawistheobviouschoice.

However, there are some decisions you need to make about fitting Raw

adjustments into your workflow. The first is which software to use? Onepossibility is the image editor offered by the camera manufacturer, with theadvantagethatthisshouldbethoroughlyintegratedwiththecamera’ssensorandprocessor. Alternatively, Photoshop (and Photoshop Elements) has a CameraRawplug-in.Asyou areprobablygoing tobeworking inPhotoshopanyway,youmightaswellstarthere,especiallyasithasmoresophisticatedcontrolsthanmostcameramanufacturersoftware,oddthoughthismayseem.Ideally,testthetwoside-by-sidewithdifferent imagesand thendecide foryourselfwhichoneyouprefertousetoworkonyourRawfiles.

Cameraraw

Photoshop’sCameraRawconverterenablesextensivechangestobemadetotheimage.Thesedialogtabs,incombinationwiththeAdjusttab,illustratethechoicesavailable.ItissensibletousethesetabsaccordingtotheOrderof

adjustments.

Exposureadjustment

Thisimageisoriginallyslightlyoverexposed,buttakenusingtheRawformat.WhenopenedinPhotoshop,theRawconverterallowschangestobemadetotheexposure,whitebalance,andnumerousothersettings.Thefinalshot(left)hashaditsexposurereducedby1/5stop,andchangesmadetothesettingsincluding

acustomwhitebalancetoenhanceshadows.

Rawadjustments

Another decision is which adjustments to make when you are converting theRawfile,andwhichonestomakelaterwiththenormalPhotoshopeditingtools.TheExposureandWhiteBalanceadjustmentsareclearwinnersinRaw,becausetheycanrestoreoriginaldata,whilesomeothers,suchasSharpness,areusuallybestleftuntillater,astheyuseessentiallythesamealgorithms.

Moredifficult to decide is the contest betweenRawadjustment and camera

profiling.Ifyouuseprofilingsoftwaretocreateaspecificcameraprofile,thisisonlygoodforimagesthathavenotbeenadjustedduringopening.Basically,youcan’thaveboth.

One alternative is to restrict the Raw adjustments to tonal range (that is,

Exposure, Shadows, andBrightness in Photoshop’sCameraRaw plug-in) andthenassigntheprofile.AnotheroptionistousetheCalibratedialogtomakethesameprofileadjustments.Ifyouarehavingproblemswiththewayinwhichtheplug-in reads non-neutral colors, this may be sufficient reason for using thecameramanufacturer’sRawadjustmentsoftwareinstead.

Photoshop CS automatically opens a Raw file and displays an adjustment

windowthatoffersalltheoriginalcamerasettingsandpossiblymore,dependingonthecamera,althoughthemenustructureisdifferent.Thisiswheretobegin,andinmanycases,thissetofdialogscantakecareofallthatyouneedtodotoanimage—one-stopoptimization.

PotentialRawworkflow

CameraCalibrationwindow

1Compensateforerrorsinreadingthecamera’sprofile,ideallybyloadingapre-

preparedprofile.

Basicwindow

2SetWhiteBalance,adjustingwithTemperatureandTintsliders.

3(optional)ChooseAutoadjustmenttoseewhatthesoftwarerecommends,butdon’tnecessarilyusethis.

4 Adjust Exposure for the overall brightness, favoring the high values andpayingattentiontohighlightclipping(settheclippingwarningon).

5AdjustRecovery,ifnecessary,torecoverclippedhighlightsbyreconstructingfromremainingoneortwochannels.

6AdjustFillLightifnecessarytoopenupshadows,beingcarefulnottooverdothis.

7AdjustBlacksifnecessary,effectivelytosettheblackpoint.

8AdjustBrightnessifnecessary,toalteroveralltonalrange(thiscompressesorexpandsshadowsandhighlightswithoutclippingthem,providedthatthesliderisusedmoderately).

9AdjustContrasttofine-tunemidtonecontrast.

10 Adjust Vibrance and/or Saturation to achieve the desired color saturation.FavortheVibrancecontrol,whichhasbuilt-inprotectionagainstclippingwhenparticularhuesapproachfullsaturation.

ToneCurvewindow(optional)

11Ifnecessary,makefineadjustmentstothetonaldistributionafterworkingintheBasicwindow.

HSL/Grayscalewindow

12Tweakindividualcolorsifnecessary.

Detailwindow

13AdjustSharpnessonlyifaimingdirectlyforaspecificoutput.

14 Reduce noise in a high-ISO image by adjusting Luminance Smoothing tocontrol luminance (grayscale) noise and Color Noise Reduction to controlchrominance noise. Otherwise, perform this with a specialist noise-reductionprogram.

LensCorrectionswindow

15CorrectcolorfringingduetolensdefectswiththeChromaticAberrationR/C(red/cyan)andB/Y(blue/yellow)sliders.

16Correctcornershading ifnecessary(typicallywithawide-angle lens),usingtheVignettingAmountandMidpointsliders.

17Forgreatercontrol and tocorrector introducevignetting tocrop selectionsusethePostCropVignettingsliders.

WorkingwithPhotoshopandRaw

Adobehasworkedhardtomakesure thateditingRawfiles inPhotoshopisasintuitiveandseamlessaspossible.

TheWorkflow Options are accessed from a clickable line at the bottom—

these are color space, bit-depth, and size and resolution. The Raw Adjustcontrols,fromtoptobottomintheorderinwhichyouwouldnormallyusethem,areWhite Balance (presets plus color temperature and tint sliders), Exposure,Recovery, Fill Light, Blacks, Brightness, Contrast, and two color saturationcontrols:VibranceandSaturation.

TheimageasopenedintheRawAdjustwindow(top)andthefinalimage,after

adjustment(above).

Settingwhitebalance

This is why it doesn’t matter which white balance setting you choose whenshootingRaw—simplyset ithere.Thereare threewaysofdoing this,offeringmuchgreater control than in-camera.The simplest is the dropdownmenu thatreplicatesthechoiceinthecameramenu,andthedefaultisAsShot.

Alternatively,youcanusethecolortemperatureslider,whichoperatesonthe

Kelvinscale.Onceyouhavegotclosetothewhitebalancesetting,fine-tuneitwiththeTintslider—thisaddsmagentawhenslidtotheright(+)orgreenwhenmovedleft(–).

Finally,youcanalsousetheWhiteBalancedroppertoolatthetopleftofthe

mainwindowtoselectatoneintheimagethatyouknoworwanttobeneutralgray.Thesliderscanthenbeusedtomakeanyfurtheradjustments.

Midtoneadjustments

Following the all-important exposure adjustments, use theBrightness slider toaltermidtoneswithinthesetblackandwhitepoints.FollowthiswithContrast,whichalsoworksprincipallyonthemidtones.FillLightperformssimilarworktotheShadow/Highlightcontrolinopeningupshadowdetail,andrunsthesamerisk of false appearance if used too aggressively.TheSaturation control has anewslider,calledVibrance,whichminimizesclippingasfullsaturation inanyone hue is approached, so this is generally a safer alternative for photographythantheSaturationslider.

Adjustingexposure

ThisfeaturealonemakesRaweditingworthit:theabilitytore-visittheshotandselectanexposuresettingupto2ƒ-stopsbrighterordarker—atotalof5stopsreal range. Ideally, work from the top down through the adjustment sliders.WatchthehighlightsasyoudragtheExposuresliderfirst.Alsoconsiderholdingdown the Option/Alt key as you move the slider. This reveals any highlightclippingascoloredareasoutofablackbase,andsoisanidealwayofsettingthewhitepoint—inthesamewayasyouwoulddoitinLevels,butbetter,ashereitis on more of the image data. Typically, for a normal image, show just thebeginningsofclipping.Asthecoloredareasshowindividualchannels,onlypurewhite (thecombinationofall three) indicatescomplete (255,255,255)clipping.Aslongasonlyoneortwochannelsareclippedinthehighlights,theRecoveryslidercanrestorepixelsbyreconstructingfromtheremainingchannel(s).FollowwiththeBlacksslider,whereholdingdownOption/Altshowsshadowclippingoutofawhitebase.

Whitepoint,blackpoint

AdvancedRawAdjustment

With shooting Raw proving to provide the best option for creating optimumimage quality, software manufacturers are working hard to produce Rawconvertersthatallowyoutoundertakemoreandmorepost-productiontasks.

Rawconvertersnowgobeyondexposure,brightness,andcoloradjustments,

with some now offering sharpening, lens aberration adjustments, noisereduction,rotation,andevenblack-and-whiteconversion.Thenumberandtypeof extra features varieswith the program.A sign of the direction being takentoward comprehensive post-productionwithin theRaw converter dialog is thearrival of retouching tools,whichwork atmuchmore localized levels.Expectmorefeaturesandmoresophisticationtobeadded.

ChoosingaRawconverter

Although Photoshop is probably the best-known Raw converter, cameramanufacturersprovidetheirownconvertersoftwarebundledwiththeircameras.ThismayhavetheadvantagethatitisdesignedtoworkwiththeirspecificRawfiles.Thisisoffsetbyweakersoftwareengineeringrelativeto,say,Adobe.Themarket for Raw conversion has expanded and become more competitiverecently, and there are now many choices, not least among the new class ofworkflow software, including Lightroom, Aperture, DxO Optics and CaptureOne.Ideally,downloaddemoversionsofdifferentRawconvertersoftwareandcomparetheresultsforyourcamera.BecauseRawformatallowsalterationstobe made to the original exposure data received by the sensor, use it beforeimage-editingtools.

RetainingRawadjustments

Once you’ve made adjustments to a Raw image, you have to save it into adifferentformat—withTIFFbeingtheusualchoice.Inotherwords,youcannotoverwrite the original, which is a good thing. An open-source Raw format,DNG, promoted by Adobe, is a saveable format, but there are differences ofopinionastoitsusefulness.ItcanbeseenasastepawayfromtheoriginalRaw,but in a different direction from TIFF and JPEG.As for the adjustments youmakeduringopening,thesecanbesaved,andinsuchawaythattheycanbere-appliedtootherimagesifyoulike.Thereisachoiceoftwoplacesinwhichtosavethem.ThedefaultistheCameraRawdatabase.InWindowsthisisusuallylocated in the user’s Application Data folder as Document and Settings/usernameApplicationDataAdobe/CameraRaw (Windows), and inMacOS in theuser’sPreferencesfolderasUsers/username/Library/Preferences(MacOS).Theadvantageof savinghere is that the imagesare indexedby filecontent, so thesettingssticktotheimageevenifyourenameormoveit.Thealternativeisinasidecar“.xmp”file,whichusesthesamenameandisstoredinthesamefolder.IfyouwanttoarchivetheRawimagefileswiththeirsettings,thisisthebetterchoice.WithsidecarfilesstoredonaCDorDVD,makesurethatyoucopythemtoyourharddrivealongwiththeimagesbeforeopening.

Fixinglensissues

Chromatic aberration, resulting in color fringing as the lens focuses differentwavelengths of light at slightly different distances, and vignetting, in whichcornersappeardarkerasthelighttransmissionfallsoffradiallytowardtheedgesof the frame, are two common issues with lenses. The chromatic aberrationcorrection here is very useful if the problem exists, while the vignettingcorrection is one of several alternatives. Actually, chromatic aberrationmanifests itself in a number of ways depending on the specific lens, and theCameraRawadjustmentdealswithoneofthem,calledcomplementaryfringing.Inthis,thefringecolorsarestrongestalongsidehigh-contrastedgesintheimage,

and close to the corners of the frame. They differ in color between the sideclosesttoandthesidefarthestfromthecenter.TheR/Cslidercontrolsred/cyanfringing,theB/Ysliderblue/yellow.TheVignettingAmountsliderlightensthecorners when moved to the right (+), or darkens when moved left (–). TheMidpointslideraltersthespreadofthelightening;movingright(+)restrictstheeffecttowardthecorners,whilemovingleft(–)broadensittowardthecenter.

Before

After

After

TonewithHistogramsandLevels

Ahistogram is avisual representation, in the formofagraph,of all the tonespresentinadigitalimage.

In digital photography, a standard 8-bit scale of 0–255 shows 256 columns

frompureblackatleft(0)topurewhiteatright(255),andnormally,incameradisplaysandPhotoshop,theyarepackedtogethersothattheyjoinandtherearenogaps.Pixel brightness is plotted across the bottomon theX axiswhile thenumberofpixelsthatcontainaparticulartoneisplotteduptheverticalYaxis.

At all stages of the photography workflow, this is the single most useful

representation of the tonal qualities of an image. In Photoshop it appears as apalette (Windows >Histogram), and as an image-adjustment dialog (Image >Adjustments>Levels).Areasonablyexposed(thatis,problem-free)photographhas a nice, smooth distribution to the shape of the histogram, peakingsomewherenearthemiddleandtailingoff towardtheleftandright; thesetailsalmostreach,butdonotcrushupagainsttheedges.

Typically, thefirst timeadigitalphotograph isopenedon-screenyouwould

goimmediatelytoLevelstocheckthedistributionoftones.Indeed,foranynon-Rawimagethisisthefirstportofcallforoptimization.Unlessyouarelookingforaspecialtonaleffect,suchasaflateffectwithlimitedtones(forexampleadelicatelandscapeonafoggyday)oragraphichigh-keytreatment(forexample,a fashion shot that deliberately washes out skin tones to emphasize lips andeyes),thenthekeyprocedureinLevelsistosettheblackandwhitepoints.Thisstretchesorcompressesthetonalrangesothat thedarkestshadowsarelocatedclosetoblack,andthebrightesthighlights(excludinglightsourcesandspecularreflections)close towhite. I say“close to”because it’s customary to set theselimitstoslightlylessthanfullblackandwhite.

UsingLevels

Fromthisoriginal,followtheroutetoimagecorrectionusingtheLevelsdialog.YoucanreachthedialogusingImage>Adjustments>Levels…orbyaddinganadjustment layer to your image. Two alternative methods are shown on thefollowingpages.

1Lookatthehistogramandmovethewhiteinputsliderleftto

thefirstgroupofpixelsanddothesame(totheright)withtheblackslider.Itwillthenlooklikethehistogrambelow.

2Youcanfine-tunetheLevelsbyholdingOption/Altasyou

drageachslider,revealingthe“clipped”areaswheredetailhasbecomepureblackorpurewhite.

FinalImage

1Thismethodinvolvesselectingthelightpoint,darkpoint,andmidtonefromtheimageusingtheeyedroppersatthebottomrightoftheLevelsdialog.Startwithdarkpoint.

2Asyouselectthedarkandlightpoints,thehistogramwill

adjustaccordingly.Finally,clickontheMidpointdropperandclickonanareaoftheimagethatshouldbeaneutralgraytoadjustthecolor.

ToneAdjustmentswithCurves

For more precise and more localized tonal adjustment turn to the Curvescommandinyourimage-editingsuite.

The characteristic curve plots exposure against density on a graph, and the

shapeof thecurve revealssuch thingsashowcontrasty the response is. In theCurvesdialog,thisischangedtoagraphinwhichthehorizontalistheInput(theoriginaldensityofpixels) and thevertical axis is theOutput (thechangesyouapply).Thecurveappearsbydefaultasastraightdiagonalline.Becauseyoucanselectanynumberofpointson thecurveand thendrag themtowarddarkerorlighter, this is amore flexible tool than Levels.Open it by going to Image >Adjustments>Curves.

Clickingonanypartoftheimageshowsonthegraphasasmallcircle,which

is a useful way of seeing how the tones are distributed. Command-clicking(Mac)orCtrl-clicking(Windows)addsthesepointstothegraph,soyoucanthenuse them to drag that part of the curve lighter (higher) or darker (lower).Midtonesareinthecenter,shadowsaredowntotheleft,andhighlightsuptotheright. Dragging points alters the shape of the curve and, just as with acharacteristiccurve,anS-shapeindicatesamorecontrastyimage,andareverseStheopposite—aflatimage.Thisismuchmoreeasilyunderstoodvisuallythanin a description, and the selection of sample curves best explains the possiblecorrections.

Curvespresets

Recent versions of Photoshop have introduced preset Curves. Clicking on theCurvesdropdownmenuprovidesachoiceofbasicbutpotentiallyusefulsettingsto try. These include Darker, Lighter, three strengths of Contrast, and moreartisticsettings,suchasCrossProcess,Negative,andColorNegative.

Curveadjustmentswithsamples

Inthisexample,Cmd/Ctrl-clickingisusedtosamplethetonesinthisimagethatwewant toadjust.The threecontrolpointsareadded,andare thendragged tomake the highlights brighter and shadows darker—in otherwords, to increasethecontrast.

Threepointsontheimageandtheirmarkersontheadjustedcurve.

FinalImage

TypicaltonaladjustmentswithCurves

TheCurve graphs shownhere are can be used as the starting points for somecommoncorrections.Individualimages,however,shouldalwaysbeassessedontheir own merits, and these curves may need tweaking. Note that all thevariations shown here are within the set black point and white point limits.AlthoughthesecanbeadjustedusingtheCurvestool,bydraggingtheendpoints,IprefertouseLevels.

Shadows/HighlightsTool

TheShadows/Highlights toolwasoneof themajornewfeaturestobereleasedwiththefirstversionofPhotoshopCS.

Thetoolusessliders,andsocarriestheadvantageofbeingquickandeasyto

use, although with the possible disadvantage of “hiding” some of theinformation.

In particular, itworks differently from the other optimization tools, such as

Curves and Levels, with algorithms to control effects across specific tonalranges. Its primary intent as designed by Adobe is to lighten shadowsrealistically,inparticularforbacklitimages.However,itsalgorithmsforalteringthe contrast in the midtones alone are possibly more important for manyphotographers.

Whatmakes thisdialogspecial is that the lighteninganddarkening thatyou

canapply isbasednotsimplyona rangeof tonesbutalsoonasampledrawnfromthesurroundingpixels.Alladjustmentsneedtobejudgedvisually,ratherthanbyvalues.Togetthemostoutofthispowerfultool,firstassesstheimageandthechangesyouwouldliketoseemade.Thenworkdownthroughtheslidercontrols from top to bottom, if necessary going back to tweak the effects.Beware of over-correcting, as artifacting is likely—halos around edges andbanding, as well as unrealistically light shadows. Open by going to Image >Adjustments>Shadows/Highlights...

Shadows/Highlightscontrols

Amount

Thisadjuststhestrengthoftheeffect,andhastobeusedinconjunctionwiththenexttwosliders.

TonalWidth

Thisspecifiestherangeoftheshadows.50%takesituptothemid-point,whichwill usually be too much. Decide from the image itself which shadows needlighteningorhighlightsdarkening.Toohighawidthwillcauseartifactingandalsolookunnatural.

Radius

Untilyouhaveexperiencewiththiscontrol,itistheleastintuitiveofthethree.Itsets the radiusaroundeachpixel that issampled, inorder todecidewhether itbelongsintheshadowgrouporthehighlightgroup,andismeasuredinpixels.Moving the slider to the right enlarges the sample area.Adobe recommends aradiusapproximatelyequaltothesizeofthesubjectofinterest.

Adjustments

ColorCorrection

Thisaffectsonlytheareasthathavebeenchangedwiththeslidersabove,sothestrength of its effect depends entirely on how strong an adjustment you havemade.Movethesliderrightformorecolorsaturation,leftforweaker.

MidtoneContrast

For many of us, this is the most important control, because it achieves animportant effect not possible any otherway. Inmost photographs, themiddlerange of tones contains the important elements. You can easily find manyimages in which youwould like to increase the contrast in this zone withoutdeepening the shadows or lightening the highlights. There is a limit to howcloselyyoucouldachievethiswithCurves.WiththeShadows/Highlightsdialog,however,youcan treat thegroupsof slidersasawayofprotecting them—theMidtoneContrastsliderthenworksontheremainingpartsoftheimage.

BlackClipandWhiteClip

Normallyyouwillnotwant toclipshadowsorhighlights,as thissimply losesimagedata.

InthisimagetheShadows/Highlightstoolhasbeenappliedtobringoutdetailintheshadowyforegroundwhileatthesametimeintroducingalittlemorewarmth

tothebrighthighlightareasinthebackground.

Sharpening

Perhapsoutofallthecontrolsthatdigitalimagingputintothehandsoftoday’sphotographers,sharpeninghasbeenmostwidelyabused.

The reason for this is that sharpening is a subjective impression and not a

measurabledetailofthephotograph.Ahigh-contrastimage,forexample,tendstolooksharperataglancethanaphotographwithmutedtones.Thereisalsonogoodmeasurement of sharpness.Most evaluations are in terms of “too sharp”and“not sharpenough.”This isn’t to say that thesearepoordescriptions, justthat they don’t transfer well from one viewer to another. It reinforces theprinciplethatthephotographershouldmakethejudgment.

The factors that give an impression of sharpness are acutance, contrast,

resolution, and noise. Acutance is how abruptly one tone changes to anotheracrosstheimage,andthemoreabrupttheedgebetweenoneareaofpixelsandanother,thehighertheacutance.Contrasthasaneffectinthatanedgebetweenblackandwhitelookssharperthananedgebetweentwograytones.Resolutionis the degree of detail, andmore detail looks sharper than less. Finally, noisebreaks up the image and reduces the overall detail, although sometimes it canhave theopposite effect and add to the sharpness simplybybeing itself sharpanddefinite.

Because sharpness and sharpening are such perceptual issues, we have to

consider how the photograph is going to be seen—under what conditions, atwhat distance, and what size. Because some of the sharpening controls aremeasuredinpixelsratherthanpercentages,thesizeandresolutionofthedigitalimagedomatter—a1-pixel radiushasamuchgreater effectona screen-sized

640×480imagethanonahigh-resolution3,000×2,000image.Theconditionof the original image is also a factor. A detailed, high-quality image, forexample, needs a different kind of sharpening technique (finer,more detailed)thandoesanimagethatsuffersfrom,say,lowresolution,slightlysoftfocus,ornoise.

Ultimately,twothingsstandout.Thefirstisthateveryphotographneedstobe

sharpenedinawaythatisappropriatetoit,sojudgeeveryphotograph—oreverysetofsimilarphotographs—onitsownmerits.Theother,importantpoint,isthatsharpening should be the last action you perform on an image before it isdisplayed—whetherasrepro,fineartprint,orontheWeb.Sharpeningcanonlybe judgedon itsappearanceas intended,andneversharpenanoriginal,onlyacopy. If you are shootingRaw, then theRaw files are your true originals, buttheir optimization represents an investment of time and skill, and you mayconsidersaving thefinishedTIFFin itsunsharpenedform.Sharpenedversionsforvariouspurposescanbegivenaslightlyamendedfile-name(suchasadding“sh”).Note that repairing focusblur andmotionblur involves sharpening, butshouldnotbeconfusedwiththesharpeningdiscussedhere.

Sharpeningandthirdparties

Wheneveranimagemovesoutofyourdirectworkflowcontrol,itisabsolutelyessentialthatotherpeopleknowwhetherornotithasbeensharpened.Ifithasnot,youandtheyshouldagreeonhowitwillbesharpened.Becauseofall thevariables (see Factors governing sharpness, below), it is clearly better not tosharpenbeforedelivery,buttakenochancesthatthisisunderstood.Inrepro,theimagemaygothroughseveralpeople,includingthepictureeditor,designer,andprinter, and there is a risk that the sharpening information gets lost, with theresultthattheimagefinallyappearssoft.

Factorsgoverningsharpness

Factorsgoverningsharpness

1Imagesize.

2Qualityofimagedetail.

3Reproductionsize.

4Printerqualityandsettings.

5Viewingdistance.

6Yourtaste.

Varyingdegreesofsharpness

Sharpeninganimageshouldideallyaddtoitsoverallimpact,notmakeitappearunnaturaloraddartifactstoit.Tell-talesignsofoversharpeningarehighlevelsof what appears to be grain, even in areas outside the image’s main focusedareas,andpixelationarounddetailedareas.

Original,Sharpened,Oversharpened

BasicSharpening

As discussed, sharpening is concernedmorewith subjective judgement than ameasurableprocess.

Certainlythereareobviousartifactstolookoutfor,suchasthedreadedhalos,

butultimatelywhatandhowmuchyousharpenisdowntoyourpersonaltaste.You may, for example, disagree with some of the results here and on thefollowingpages,andthatisasitshouldbe.Yourtasteisthefinalarbiter.

AlthoughPhotoshophasSharpen,SharpenEdges,andSharpenMore filters,

these are rough and ready, and allow no fine-tuning, so are best ignored. TheusualprofessionalsharpeningtoolistheUnsharpMask.Asawayofincreasingsharpness,thissoundslikeanoxymoron,buttheapparentillogicalityisbecausethetermisaholdoverfrompre-digitaldays.Infilm-basedrepro,anout-of-focuscopy of the imagewas sandwichedwith it as amask, and the result, as if bymagic,wasasharperimage.Theexpression,oftenshortenedtoUSM,hasstuck.

The digital process, however, is quite different, and works by resampling

pixelssothecontrastbetweenneighborsis increased.Atapixel level,anedgelooks like an area of dark pixels against an area of light ones. Increasing thetransition between them—making the dark pixels darker, and the light pixelslighter—is the key way of heightening the contrast, or sharpening. Mostsharpeningtechniques,includingUSM,canbeadjustedtosuitdifferentimagesbythreevariables:amount,radius,andthreshold.

Inpractice,gettingtheserightforaparticularimageiscomplicatedbyasetof

factorsthatincludethesizeandqualityoftheimage,theviewingdistance,andyourowntaste,whichissubjective.ProprietarysharpeningapplicationssuchasPower Retouche Sharpness Editor and Nik Sharpener Pro take a moresophisticated approach than USM, include more variables, and can protectsensitiveareasofaphotographsuchasintricatedetail.

UnsharpMaskcontrols

ThethreestandardsettingsareAmount,Radius(alsoknownasHaloWidth),andThreshold,andbetweenthemtheyprovidegood,thoughnotperfectcontroloverthesharpening.Beaware that thereareanumberof sharpeningalgorithms (ofwhichPhotoshop’sUSMisjustone),andmostaimtoheightenlocalcontrast.

Amount

This, expressed as a percentage, is the intensity or strength of the sharpening.Opinionsvary,asthissettingdependsverymuchonpersonaltaste,butforhigh-resolutionimages,valuesbetween150%and200%arenormal.

Radius

Thisisthedistancearoundeachpixelthatisusedforcalculatingthesharpeningeffect.Asmallradiuswillsharpenanarrowedge,alargerradiusabroaderband.Itaffectsthecoarsenessofthesharpeningandismeasuredinpixels.Thewideritis, thewider that edgeswill appear, and if it is set toowide, a “halo”appearsalong edges (hence the alternative name Halo Width). For high-resolutionimages,aradiusofbetween1and2isnormal.

Threshold

This controls the level of difference between adjacent pixels that will besharpened,andservesasakindofprotectionforsmoothareaswithfinetextureand little detail.With the threshold at 0, everything is sharpened.Raising it alittle prevents the sharpening being applied to areas in the image where thedifferencebetweenpixel values is small, such as sky and skin. It concentratesthe sharpeningmore on the distinct edges,which are usually consideredmoreimportant,andwithoutit,thesmoothareascanappear“noisy.”Itismeasuredinlevelsbetween0and255.Setting the threshold to4, forexample, restricts thefiltertoareaswherethedifferencebetweenadjacentpixelsisgreaterthan4—forinstance, neighbors 128 and 133would be sharpened, but 128 and 130wouldnot. For a high-resolution photograph, values between 2 and 20 are typical,reflectingthedifferenceinimagecontent.

TheresultofsharpeningwithaThresholdsettingofzero.

TheresultofsharpeningwithaThresholdsettingof10.

Whensharpeninggoeswrong

Whensharpeninggoeswrong

Oversharpeningisresponsibleforruiningmanythousandsofphotoseachyear.Undersharpening is also an errorof akind, but difficult tomeasurebecause itreliesonpersonaljudgment.Commonfaultsareasfollows,andcanbeavoidedbyreadjusting theAmount,Radius,orThreshold,orbyusingoneof themoreadvancedtechniquescoveredlater.

Halo

Alsoknownasnegativecontour,thisisanedgeeffectinwhichatoo-brightortoo-darkbandofoneormorepixelsseparatestwotonalareas.

Aliasing

Anti-aliasing is thewell-knownsoftware technique for softening the“staircasesteps”thatoccurondiagonallinesandedgesindigitalimages(duetothesquarestructureofpixels).Sharpeningcanremovetheanti-aliasing.

Colorartifacts

Unwanted colors appear at the margins of other colors, particularly in high-contrastandlow-qualityimages.

Localextremeartifacts

Clumpsofalmost-blackoralmost-whitepixels.

Haloeffect

Colorartifact

AdvancedSharpening

Whenitcomestosharpening,notonlyiseveryimageunique,butdifferentareas

withinthesameimagemaywellrequiredifferinglevelsofsharpening.

Ultimately,what thismeansis that toachievesuccessfulsharpening—that is

the impression of sharpness but without any artifacts—you need to applyselectivesharpening.TheThresholdcontrolshownonthepreviouspagesisthestandardmeansofapplyingselectivity,butthereareothers.Typically,themostsharpening is wanted along edges and in areas of fine detail, and the least(indeed,oftennone)iswantedinsmoothareasandespeciallyinzonesthatareoutoffocus.Animportantcaveatisthatsomeareasmayhavesuchintensityofdetailthattheyreactbadlytosharpening—brightlylitfoliageisaparticularcase.

Havingidentifiedtheareastoselect,youcandothisinanumberofways.One

ismanually,byairbrushinginamaskinglayertocreateaselection.Anotheristouseanotherfiltertofindtheareastobesharpened—theexampleshownoppositeuses the Find Edges filter. Because the level of detail usually varies betweenchannels, another technique is to apply sharpening to one channel only. AnextensionofthisistoprotectcolorsfromsharpeningbyswitchingmodesfromRGB toLab and applying the sharpening filter to theLightness channel only.Finally,andmostconveniently,considerthird-partysharpeningsoftwarethatisusually available as plug-ins to Photoshop. Two specialist programs inparticular,nikSharpenerProandIntellisharpen,useadvancedalgorithms.

Anotheradvancedapproachtosharpeningistoapplythefilterstwiceormore

atalowlevel.Multipasssharpening,asitisknown,isthebestwaytoapplyanysharpenerforhigh-qualityresults,becauseitreducestheriskofartifacts.Itcallsfor experiment, but once you are familiar with its effects, it becomes easy toexecute.Batchprocessingmakesitmoreconvenient.

SmartSharpen

With the introduction of PhotoshopCS2 in 2007, an additional Sharpen filter

was added—Smart Sharpen. This filter offers greater flexibility than UnsharpMask. First, Smart Sharpen provides a variety of sharpening options, foundunder the Remove menu—Gaussian Blur, Lens Blur, and Motion Blur. LensBlur usually provides the best results for standard sharpening. Additionalflexibility comes in the form of the Fade Amount, TonalWidth, and RadiussliderslocatedundertheShadowandHighlighttabsonceAdvancedisselected.Together these options provide much greater control than the Unsharp Maskfilter.

Sharpentwice

Onewayofreducingtheriskofsharpeningartifactsistoperformtwo(ormore)sharpening passes. Additionally this allows you to aim the sharpening atdifferentpartsoftheimage.Forinstance,thefirstpasscouldbegentlebutwithno threshold, to subtly improve fine texture, followedbya secondpass that isstrongerandaimedattheedges,whilesettingathresholdtoprotectthesmootherareas.Thisworkswithwhateversharpeningtechniqueyouuse,butclearlyneedsexperimentandexperience.Theadvantageofdoingthisisthatthesecondpass

multipliesthesharpeningeffect,whileonlyaddingtotheartifacting.So,ifyousharpenonceat100%andasecondtimeat125%,thesharpeningeffectwillbe100+(2x2x125)=600%.Theartifactgeneration,however,willbeonly100+125=225%.

ConverttoLab

High levels of sharpening can often lead to color artifacts, particularly alongedges.Agoodsolution,worthconsideringasyourdefaultsharpeningtechnique,is toconvert theimagetoLabandsharpenjust theLightnesschannel.This,asyoucanseebylookingattheaandbchannels,containsalmostallthetexturaldetail. The gentleness of the color gradations in the two color channels ispreserved.ConvertbacktoRGBwhenfinished(LabisalsousedbyPhotoshopasitsconversioncolorspace,andswitchingbetweenthetwolosesnoquality).

SharpeningwiththeFindEdgesfilter

It’stheedgesofanimagethatcanprovidethegreatestimpressionofsharpness,yet theUnsharpMaskfilterdoesnotpayanyparticularattention to these.TheThresholdsettingwithahighradiuswillconcentratesharpening,tosomeextent,ontheedges,buttherearemorefocusedtechniques.

1UsingtheChannelspalette,identifythechannelwiththemost

contrastin.Inthisphotograph,thedancersaremostclearlydistinguishedbytheredchannel.DuplicatethechannelyouidentifiedbydraggingittotheNewChannel(turningpaper)iconatthebottomoftheChannelspalette.

2Workingonthenewlycopiedlayer,selecttheFilter>Stylize

>FindEdgesfilter.Thiswillhighlighttheedgesonly,andbyworkingonthenewchannel,itwon’taffecttheimageitself.Sincewe’relookingtohighlighttheedges,notthe

majorityoftheimage,clickImage>Adjustments>InvertbeforeclickingtheLoadChannelasSelectionbutton(dottedcircle)atthebottomoftheChannelspalette.

3SwitchbacktotheLayerspaletteandclickonthebackground

layertomakeitactiveagain.Youshouldseeyournewlymadeselectionimposedontopoftheoriginalimage,ratherthanthealteredchannel.

4Withtheselectionstillactive,applytheFilter>Sharpen>

UnsharpMask(USM)totheimage.Itwillonlyworkontheselectedareas.

5Thefinalimage,withextrasharpeningappliedtotheselected

areas.

IMAGE EDITING PART III

IncreasingImageSize

As sensor resolution has been steadily increasing year on year, the issue ofincreasing the size of an image—upscaling—has become more and moreredundant.

However,evenwithtoday’s20+-megapixelsensors, theremaystillbe times

whenyou’renotsureifyourcamera’sresolutioncanfillthesizeoftheprintyouwant.

Andso thequestion still arises,howmuch is itpossible to enlargeadigital

image and still have an acceptable level of detail? There is a 300 dpi rule ofthumb in repro,but it isnomore than that—asafe industrystandard.The twoprincipal factors are the line frequency (line screen) of the printer, and thepercentageofthisthatthedigitalimageshouldbe.Newspapersprintat85,mostmagazinesat133-150,high-qualityillustratedbooksat200,andafewartbookshigher still. The percentage is very much a matter of opinion, but generallybetween 150% and 200%. In other words, even excluding the low quality ofnewspapersfromthecalculation,theacceptableresolutionforadigitalfilecouldbebetween200and300.Andthisdeterminesthesize.

Interpolation

Goingbeyondtheselimitsinvolvesinterpolation,andtherearegoodargumentsfor doing this yourself so that you can check and guarantee the result. Theimportant choice is the method, meaning the interpolation algorithm. WithinPhotoshop, thechoice issimple forphotographs—Bicubic. Itgivesasmoother

tonal gradation than the other two (Nearest Neighbor and Bilinear) and alsobettersuitsthecomplexstructureofaphotograph,usuallylackingexactstraightedges.It’simportanttorealizethatthereisalwaysalossofqualityinupscaling.How much is acceptable is a matter of opinion. Some users believe thatincremental upscaling (say, 10% at a time) gives superior results, as withsharpening,althoughIhaveseennoside-by-sidecomparisonthatbearsthisout.

Going beyond Photoshop, there are proprietary applications that promise

betterresults.Oneapproachisasuiteofalgorithmsthatanalyzethedetailinanimageandapplydifferentmethodstodifferentareas—maintainingsharpedges,forexample.PhotoZoomisoneofthese.

Anotherapproachistoconverttheimagetoadimension-freeimageformatso

that it can be output at a larger scale.GenuineFractals is an example of this.Comparisons between these different methods vary depending on the image.Thereis,however,adifferenceinqualitybetweeninterpolationalgorithms,andthe best do not blindly apply the same techniques to every part of an image,insteaddiscriminatingaccordingtothetonal,color,andtexturaldifferences.

Filling in the gaps like this tends to create unsharpness. Upscaling is

analogous to stretching, and most methods fail to hold edge sharpness. Inenlarging an edge, normal resampling adds an intermediate value between thedark and light pixels,which softens the appearance.After upscaling, a secondsharpening operation may be necessary, although proprietary upscalingtechniquescancomplicatemattersiftheyalsoincorporateedge-sharpening.

Resolutionandsharpness

Therelationshipbetweenresolutionandsharpness,whilesuperficiallydistant,isin fact close and intricate. Resolution in an image is the amount of detailrecordedandsoisobjective,whilesharpnessistheappearanceofdefinition,and

soisperceptualandevenamatterofopinion.Thatwouldseemtosetthemapart,butinupscalingtheyconverge.Theconfusionarisesbecausethewholeprocessofcreatingalargerimagefromasmallerversioninvolvesguessworkandopticaltricks. Digitally, both processes use interpolation, which means re-calculatingthe values of existing pixels. Sharpening can certainly help in creating theimpressionofgreaterdetailaroundedges,butitneedstheusualcare,andaddstothevariables.Inpractice,upscalingwithsharpeningcantaketimeandinvolvesmultiplechoices.

Photoshop’sinterpolationoptions

When it comes to rescaling,Photoshopprovides three coreinterpolation algorithms. Nearest Neighbor is the simplest,expandingpixelsintosquareblocksofpixels,whichcanbequite ugly. Bilinear andBicubic, on the other hand, softenthe edges using data from the surrounding pixels, creatingsmootheredgessimilartoanti-aliasedtext.Bicubicisfurthersubdivided into Bicubic (for smooth gradients), BicubicSmoother(bestforenlargement),andBicubicSharper(bestforreduction),whichareallself-explanatory.

Nearestneighbor

Bilinear

Bicubicsmoother

Framecomposite

With a static subject and time, there is a simple workaround to increaseresolution when you’re shooting—take a series of overlapping images with alongerfocallength,andthenstitchthesetiledimagestogether.

Overlappingimagesbeforetrimming.

ResizingSoftware

There are fewer examples of dedicated upscaling software on themarketthanthereusedtobe,withperhapstheneedforsuchprogramsdecreasing.

Themost popular two cross-platformprograms areBenVista’s PhotoZoom

Pro(areincarnationoftheDutchsoftwareS-Spline),andGenuineFractals.

Genuine Fractals is not, strictly speaking, dedicated to upscaling, but was

developedasascalelessimagefileformat.Neverthelessthisisprobablyitsmostvaluable use.What both have in common is that the algorithms they use forinterpolation are much more complex than that for Bicubic—the Photoshop

defaultforphotographicimages.

Asimple200%scaling

GenuineFractals

OnOne’sGenuineFractals’Photoshopplug-in isdesigned tobeused either toscaleupimages,orasanalternativeandspace-efficientwaytosavefiles.Intheformercase,itisespeciallygoodatcreatinglargerfilesfromsmalleroriginals,at up to 600%without serious loss in quality. In the latter case it can createlosslessarchivesofyourimagefiles.

PhotoZoom

Formerly marketed as S-Spline, and still using the same S-Spline algorithm,PhotoZoom is designed solely for image enlargement. It uses adaptiveinterpolationsothatthepartsoftheimagethatneedsharpeningthemost(withdetail) are given more sharpening than featureless areas, and it does this byanalyzingthestructureoftheimage.Asthedesignerssay,it“works,sotosay,more‘aggressively’inareaswithhighcontrast(andthisisexactlywheredetailsneedtobepreservedmost),whileitinterpolatesmoregentlyinsmootherareas.”

DigitalColorSpaces

Thecolorsavailableforuseinadigitalimagearedeterminedbycolorspace.Acolorspaceisamodelfordescribingcolorvalues,andhasa“gamut,”orrangeofcolorsthatit iscapableofrecordingordisplaying.Byconvention,theusualwayofillustratingthisisasshownonthenextpage.

Some spaces are bigger than others, with obvious advantages. A perfect

illustrationofwhycolorspacemattersandwhyitissometimeslessthanidealisthe very problem of showing what it looks like on a printed page. Thecombinationofpaperandprintinginksactuallyshowsfewercolorsthaninreallife,whichmakesCMYKthesmallestcolorspaceinnormaluse.Thediagramshereare,ofnecessity, inaccurate.Theareaoutside themarkedspacescontainscolorsubtletiesthatareimpossibletoshowinprint.

BecauseRGBisstandardfordigitalcamerasandcomputerdisplays,themost

commonlyusedcolorspacesarevariantsofthis.Ahigh-endcameraallowsyouto choosewhich space towork in, as do image-editing programs.Despite theseveral possibilities, there is at the moment just one recommended space forprofessionalphotography,andthatisAdobeRGB(1998).Thereasonsarethatit

hasthelargestrangeforanRGBspaceandiswidelyacceptedforprepresswork.TheotherRGB spaces offered are all designed for specific non-prepress uses,principally matching monitor types and printing directly from the camera ormemorycard.

RGBmaybe standard, but there is a larger color space available for digital

imaging, and it has striking advantages. This is CIE Lab (strictly speaking,L*a*b*),developedin1976bytheCommissionInternationaled’Eclairage,anddesignedtomatchhumanvisionascloselyaspossible—atleast inthewayweperceive and appreciate color. Thus, it uses three channels, one for brightnessand the other two for opposing color scales. L* stands for luminance (that is,brightness),a*forared-greenscaleandb*forablue-yellowscale.Beingalargecolorspace,itisalsousefulforconvertingcolorsfromonemodeltoanother,asnothingislost.Indeed,AdobePhotoshopusesL*a*b*internallyforconvertingbetweencolormodes.Withallthisgoingforit,L*a*b*’sonlydrawbackisthatRGBjusthappenstobemorewidelyused.Youcanuseitinimageediting,andconvertRGBtoandfromitwithimpunity—itallowssomespecialprocedures,suchasnoisereduction.

As for CMYK, which is where most professional photographs end up, the

advice is straightforward;don’tuse it toeditorarchive images. Ifyoudo, theimagewilljustlosecolorinformation.Aswithsharpening,CMYKconversionisbestdonefromRGBat the laststepand, incidentally, isbestdonebyprepressprofessionals.

Whichcolorspace?

AdobeRGB(1998)

Afairlylargerange,andthemostcommonlyrecommendedspaceatthemomentfor photography. Good for images that will later be converted in prepress to

CMYKforprinting(asmostprofessionalphotographsare).

sRGBIEC61966-2.1

ThisstandsforStandardRGB,butitissmallerthanAdobeRGB(1998)andsonotrecommendedforprofessionalphotographythatwillbeusedforprepress.ItsadvantageisthatitmatchestheaveragePCmonitor,andisstandardforlow-endprintersandscanners.

Colormodes

Briefly, color spaces are the theory, colormodes are the practice, and can beselectedinanimage-editingprogram(Image>ModeinPhotoshop).Becausethefour modes normally available—RGB, HSB, Lab and CMYK—separate thequalities of color in different ways, they each have certain advantages forparticularphotographs:

RGB

The standard mode, by virtue of being used in all digital cameras. Widelyaccepted.Thethreecolorsarehighlyfamiliar,soeasytomanipulatechannelbychannel,usingCurvesorLevels.

HSB

SeparatesthecolorsintothethreedimensionsofHue,Saturation,andBrightness—the method most similar to the way in which we see. Therefore, highlyintuitive.

Lab

Thelargestcolorspaceavailable,andusefulinthatitsthreechannelsaredividedbetweenLightness(L),acoloraxisfromredtogreen(a),andanotherfromblueto yellow (b). The Lightness channel is especially useful for adjustmentsindependentofhue.

CMYK

Usedinprinting,withafourthblackchanneladdedtomakeupfor thelackofinkdensityonpaper.Thesmallestcolorspace,andsonotparticularlygood toworkin.

Colorspace

Twocolorspacescompared:AdobeRGB(wireframe)andCMYKPress(solid),representedin3Dandviewedfromdifferentangles.Youcanseethatinsomeplaces,theCMYKspace—whichisgenerallysmaller—exceedstheRGB,for

exampleintheyellows.

AdjustingColors

Althoughgettingcolorsasyouwant themisgenerallypartof theoptimizationprocessdescribedearlier, itmaybe that for specific creative reasons,youwillwanttochangespecificcolorsinanimage.Asusual,thereareseveralmethodsforachievingthis.

There are many tools and dialogs for making color adjustments within

Photoshop(fromtheImage>Adjustmentsmenu),andthroughthird-partyplug-ins(suchasnikColorEfexPro)andothersoftwareapplications.All relyonabasicoperation,whichistoselectarangeofpixelsandthenmapthesevaluestoanewrangeofvalues.Todothisinonestep—thatis,throughonetool—thereneeds tobeamethodofselectingpixelsbasedontheirvalues:hue,saturation,andbrightness.

Tomakeanyotherkindofselection,suchasontheshapeofanobjectinthe

photograph,youwouldfirstneedtouseoneoftheselectiontools.YoumayfindtheSelect>ColorRangefacilityinPhotoshopveryusefulifyouarelookingtoalterregionsofcolor.UnliketheHue/Saturationtool’scolorrangeselection,itsFuzzinesscanbealtered.

Hue/Saturation

The Hue/Saturation dialog is one of the most intuitive ways of making coloradjustment.Thisisbecausethetoolusesthecolormodemostcloselyrelatedtothe waywe judge colors—hue, saturation, and brightness. It helps to keep inmind that the color bar is a straightened-out version of the color wheel, withhues defined by their angle (0º–360º, as on a compass).By default, the entire

color range—called Master—is selected, but the changes can be restricted toindividualcolorsfromadropdownmenu,andevenfurtherrefinedbysamplingcolors from the image while you are in one of these ranges. The sliders thatappearonthecolorbarcanthenbeadjusted.Thetwohorizontalbarsdeterminetherangeofcolorsselected,andthetwooutertriangleslidersdeterminethefall-offorfadingfromthisrange.

TheHue/Saturationdialogpresentsanumberofoptions.Youcanadjustthecolorsintheimageusingthesetools,orapplyacolortothembycheckingthe

Colorizebutton.

Alternatively,youcanopttoaffectonlyacertainrangeofcolors.Youcanselecttherangeusingthedroppers,orfromoneofthepre-definedrangesfromthe

Edit:dropdownmenu.

Photofilter

ThePhotoshopImage>Adjustments>PhotoFilter…toolallowsyouto

simulatetheeffectofcertainfiltercolors,orcreateacolorofyourchoiceusingthestandardcolorpicker.Thisisaveryphotographer-friendlyapproach,sincetheconceptisonelong-establishedinfilmphotography,withthebenefitofan

undooption.

MemoryColors

Dependingonourgeographicalandculturalupbringing,therearecolorsthatarestronglyfixedinourconsciousness.

Oftenreferredtoasmemorycolors,suchcolorsaresofamiliartousthatwe

areable,witha fairdegreeofcertaintybeable to saywhetherornot theyarecorrectlyrenderedinadigitalimage.

Theyareknownasmemorycolorsbecausetheyseemtobeembeddedinour

visualmemory.Naturally,theyplayanimportantroleinimage-editingbecausetheyareanimmediatekeytoassessingthecoloraccuracyofaphotograph.For

memory colors, we can say whether they are “right”or “wrong,” and to whatdegree, and we can do this intuitively. Measurement is important inoptimization,aswesaw,butascolorisultimatelyamatterofperception,neverunderestimatetheimportanceofsubjectivejudgment.Ifitlooksright,itisright.

Greengrass,capturedhereundertheclear,evenlightofanovercastsky.Grassandplants—andevensomeanimals—areacrucialmemorycolor,especiallyintemperateclimatessuchastheUnitedStatesandmuchofEurope.Inthemind,memorycolorstendtobecomeslightlymoresaturated—inotherwords,the

grassisalwaysgreener.

The twomost importantmemorycolorsare thosewithwhichwehavemost

familiarity: neutrals and skin tones. Following this, there are green vegetationand sky tones.Your colormemory alsodependson the environment inwhichyou grow up—if you live inNewMexico orNorthAfrica, youwill bemoreattuned to the colors of sand and rock than if you live in northwest Europe.Adjustingthememorycolorsinaphotographinvolvesmatchingthemtoknown

samples. At it simplest, this means relying on your memory at the time ofcorrection, but you can refine the process by referring to samples that youalreadyaccept as accurate.Oneway is toopena second image that is alreadywell-adjustedanduseitforreference.

Insomecolorareas,ourcameraismoresensitivetothesubtletiesofshadethanyoureye.Areassusceptibletothisareoftenfabricswithorganicdyes,anditis

notuncommonforgreenstoappearneutraloronthewarmside.

Memorycolorsareonlyunderstoodbythemindinthecontextthatweseethemin.Placetheredfromthisimagesomewhereonitsownanditissimplyaredcolor,butinthisimage,thered(andindeedyellowandblack)clearlyneedtoappearstrong,sincetheyrepresentcommonlyunderstoodwarningcolors.

FixingNoise

Advances in DSLR sensor technology have seen ISO sensitivity settingsreachingpreviouslyundreamedof scales (ISO12,800 is common)andat suchhighsettings,noisewillcontinuetobeaproblem.

Noiseiscomplexandcomesinavarietyofforms,whichmakesitdifficultto

tackle at the time of capture. In practice, some noise is best dealtwith in thecamera—notably fixed-pattern noise—but the most useful place for noisereductionishere,inpost-production.

To repeat the key characteristic of noise, it is embedded in the imageperceptually—thatis tosay,itcanbedistinguishedfromsubjectdetailonlybyjudgment,andthatdiffersfrompersontoperson.Notonlythis,butnoisedoesnotevennecessarilydamageaphotographicimage.Photographsarenotslicesofreality;theyhavetheirowntexturalqualities,andoneofthesethathasbecomeaccepted is a certain amount of graininess from film. There are many well-known images (to name one example, the sequence of D-Day landingphotographsbyRobertCapa)thatdrawsomeoftheirpowerfromgraininess.

One implication of this perceptual relationship with detail is that noise

reduction has side effects on the rest of the image, usually softening, and thecreation of artificial-looking textures. Because of this, most noise-reductionfiltersincorporatesomekindofthresholdsettingtoprotectdetailbelowacertainlevel.Theproblemisthatahardthreshold,whichleavesfinerdetailuntouched,workson size rather thanvisual importance, and this cancreate anevenmoreunnaturaleffect,anddrawattentiontotherepairprocess.

The algorithms used in different software vary. One common procedure is

blurring(seeAveragevs.Medianbox,opposite).Anotherisfrequencyanalysis,alsoknownastheFourierTransformation,inwhichtheimageisconvertedintofrequencies; these can then be searched for structures that don’t conform toknownonesrepresentinglines,edges,andpatterns.Noneofthesemethodscanwork alone, however; all need guidance from the user. In other words, whenusinganynoise-reductionfilter,thebestyoucanhopeforistoadjustthesettingsandchoosethebest-lookingcompromise.

Photoshop

Usethistechniqueonasmallselectedareaofanimagetoseethenoiseartifactsmoreclearly.

1Opentheimageandchooseasmooth,midtonearea,where

noisewillbemostapparent.

2OpentheHighPassfilter(Filter>Other>HighPass)and

zoominontheareato100%.Applyataradiusof3pixels.

3ApplyAutoLevels(Image>Adjustments>AutoLevels)to

increasethecontrast.Thiswillexaggeratethevisibilityofthenoise.

4Desaturatetheimage(Image>Adjustments>Desaturate)to

showtheluminancenoiseseparatelyfromthechrominancenoise.

Averagevs.Median

Mostblurringfilterstakeanaverageapproach,meaningthattheysampleanareaofpixels(thesizedependsontheradiusyouset),andfindtheaveragevalue.Amedianfiltermayappeartodothesamesortofthings,butinfactitchoosesthemostrepresentativepixel.Inanextremecase,ifanareaof100pixelsissampled,inwhich there are 51 black and 49white, average blurringwill return a graypixel, while a median filter will choose black. The disadvantage of averageblurringisthatitreducesratherthanobliteratescompletelyblown-outhotpixels,while amedian filterwill replace them. The disadvantage ofmedian filters isthattheycanintroducelarge,unnatural,painterlyartifacts.

HotPixOriginal

HotPixGaussian

HotPixMedian

Original

RGB

L*A*B

Opinionisdividedonthis,butthemajorityviewisthatifaparticulartypeofnoiseappearsmostinonechannel,applythefiltertothatalone.InanRGB

image,theredchanneloftenhasthemostchrominancenoise.ConvertingtoLabmakesitpossibletoisolateluminancenoisebyselectingtheLuminancechannel,orcheckingtoseewhethertheaorbcolorchannelhasthemostchrominance

noise.

Makeaselection

Noiseismoreapparent inflat,moreuniformlycoloredareasthanit is inareascontaining lots of detail. This gives us a handy get-out clause, since these arealsotheareasthatthefiltershaveahardertimecopingwith.Toachievethis:

1Duplicatethelayeryouwishtoapplythefilterto.

2Onthehigherlayer,withasoft-edgedbrush,erasethose

areastowhichyouwouldliketoapplythefilter.(Itisagoodideatoturnoffthevisibilityofthebackgroundwhiledoingthis.)

3Applythenoisereductionfiltertothelowerlayer.Theeffect

willonlybevisiblethroughthoseareasyouerasedfromthelayerabove.

FixingLensDistortion

Lens technology is improving year on year. However, as the technologyimprovesthedesireforproducingzoomswithagreaterrange,fromwideangletolongtelephoto,haveresultedinlensesthatoftendisplaygeometricdistortion.

Gone are the days when prime lenses were obviously superior in image

quality,butitismoredifficulttocorrectdistortioninazoom—onalenswithalargerange,it’squitelikelythattherewillbebarreldistortionatthewide-angleend, with pincushion at the other, longer-focus end. Wide-angle zooms areunderstandablypopular,butthepenaltyisdistortion.Becausedistortionscanbecorrecteddigitally, there isnoexcuse for ignoring them, and thisbecomesyetanotheradditiontotheworkflow.Lensdistortioncanbecorrectedwithsoftware,althoughcurrentlythechoiceissmall.Becauselenseshaveindividualdistortioncharacteristics—andmoreimportant,withzoomlensesthedistortionvarieswiththe focal length—correction software has to be able to interpolate severalparameters,includingtheradialamountofdistortion.Ofcourse,lensdistortionmattersonlyifitisnoticeable,asitischieflyalonglong,straightlinesclosetothe edges of the picture. If it doesn’t disturb you visually, theremay be littlepointincorrectingit.

In principle, both barrel and pincushion distortion are corrected digitally by

applyingtheoppositeradialdistortion,andtoanextentyoucoulduseoneofthebasictools,suchasPhotoshop’sDistortfilters.These,however,donotallowforthevariationintheamountbetweentheinnerandouterpartsoftheframe.Lens-distortioncorrection filterscanallowfor thedifferentopticalcharacteristicsofdifferentmakesoflens.Thedegreeofdistortionalwaysincreasesoutwardfromthecenter,but thewaythisprogressesvariesfromlenstolens.Without takingthis intoaccount,youcanendupwithcorrectedstraight linesat theedgesbutunder-orover-correctionnearerthecenter.

Threecommoncorrections

Therearethreemainkindsofcorrectionthatyoumayneedtomaketothegeometryofanimage:

Type Characteristics procedure

1Lensdistortion Bowinginwardoroutwardaroundthecenter(radial).

Lenscorrectionplug-infilterthatappliestheoppositeradialdistortion,weightedappropriatelybetween

centerandedges.

2Perspectivedistortion ConvergenceofParallels,verticallyorhorizontally.

Edit>Transform>Perspectivefilter.

3Rotation Tiltedclockwiseorcounter-clockwise(aroundthezaxis).

Edit>Transform>Rotatefilter,orImage>Rotate>Canvas.

Itmaynotbeimmediatelyclearinwhichordertoapplythese,andmuch

dependsonthespecificimage.However,inprinciple.correctinglensdistortionfirstwillleavestraightlinesthatareeasiertojudgeforperspectiveandrotation.

Usingcorrectionsoftware

Correction software is judged by its effect on straight lines and, to a lesserextent, on symmetrical shapes such as circles. A grid overlay is essential formeasuring the effectof the filter, either in the filterwindoworon the appliedresultinPhotoshop—orboth.Adjustthespacingofthegridsothatthelinesareclosetothoselinesintheimagethataremostimportant.Imagedistortionisverydemanding of processing ability, and final image quality depends on goodinterpolationalgorithms.

Theidealmethodistoanalyzeeachlens,mapitsdistortion(and,ifazoom,at

everyfocallength),andthenreverseitseffectintheprogram.EssentiallythisiswhatDxOOpticsProdoes,anditiscompletelyeffective.Theonlydrawbackisthat it is entirely dependent on the time-consuming analysis that the softwaremanufacturermakes, and there isnowayof adjusting, tweaking,or creating a

userprofileforanyotherlens.AnalternativeapproachistakenbyAndromeda’sLensDoc,whichworksbydefiningpointsalongalineintheimagethatneedtobestraightened,thenstraighteningthatcurve.Andromedaalsohasamethodforuserstoprofiledistortionsforthemselves,thoughthisisverytimeconsuming.

It may not be immediately clear in which order to apply these, and much

dependsonthespecificimage.However,inprinciple,correctinglensdistortionfirstwillleavestraightlinesthatareeasiertojudgeforperspectiveandrotation.

Isdistortionapparent?

Certain types of lens distortion are only really apparent if there are long linesthatshouldbestraightandparalleltooneanother.Ifthescenecontainsnolong,straight lines, theremaybenocompelling reason todoanything to the image.Naturalscenery,forexample,usuallyhasnocleargeometry.Withtheexceptionof fish-eyes,most lenses require a small amount of correction;make a visualassessmentfirst.

Croplast

Aftercorrection,theimagewillneedcroppingtoremovethenewcurvededges,unless the softwareoffers theoptionof stretching the image to fit theoriginalframe.Forthisreason,donotcropanimagebeforeapplyinglenscorrection.Thesoftware assumes symmetrical correction around the center of the image, socroppingbeforehandresultsinaskewedcorrection.

Thisimage(left)wastakenwithazoomlenssetatitslongestfocallength,

resultinginclearpincushiondistortion.Thisiseasilycorrected(below)byusingPhotoshop’sLensCorrectionfilter(Filter>Distort>LensCorrection).

GLOSSARY

Archive

The process of organizing and saving digital images (or other files) for readyretrievalandresearch.

Aberration

Theflawsinalensthatdistort,howeverslightly,theimage.

Aperture

TheopeningbehindthecameralensthroughwhichlightpassesonitswaytotheCCD.

Artifact

Aflawinadigitalimage.

Backlighting

Theresultofshootingwithalightsource,naturalorartificial,behindthesubjecttocreateasilhouetteorrim-lightingeffect.

Banding

An artifact of color graduation in computer imaging, when graduated colorsbreakintolargerblocksofasinglecolor,reducingthe“smooth”lookofapropergraduation.

Bit(binarydigit)

The smallest data unit of binary computing, being a single 1 or 0. Eight bitsmakeuponebyte.

Bit-depth

The number of bits of color data for each pixel in a digital image. Aphotographic-quality image needs 8 bits for each of the red, green, and blueRGBcolorchannels,makinganoverallbit-depthof24.

Bracketing

Amethodofensuringacorrectlyexposedphotographbytakingthreeshots:onewiththesupposedcorrectexposure,oneslightlyunderexposed,andoneslightlyoverexposed.

Brightness

The level of light intensity.One of the three dimensions of color in theHSBcolorsystem.SeealsoHueandSaturation.

Buffer

Temporarystoragespaceinadigitalcamerawhereasequenceofshots,takeninrapidsuccession,canbeheldbeforetransfertothememorycard.

Calibration

The process of adjusting a device, such as a monitor, so that it worksconsistentlywithothers,suchasascannerorprinter.

CCD(Charge-CoupledDevice)

Atinyphotocellusedtoconvertlightintoanelectronicsignal.Usedindenselypackedarrays,CCDsaretherecordingmediuminmostdigitalcameras.

Channel Part of an image as stored in the computer; similar to a layer.Commonly, a color imagewillhaveachannel allocated toeachprimarycolor(e.g.RGB)andsometimesoneormoreforamaskorothereffects.

Clipping

The effect of losing detail in the lighter areas of your image because theexposure was long enough for the photosites to fill (and record maximumvalues).

Clippingpath

The line used by desktop publishing software to cut an image from itsbackground.

CMOS(ComplementaryMetal-OxideSemiconductor)

AnalternativesensortechnologytotheCCD,CMOSchipsareusedinultra-highresolutioncamerasfromCanonandKodak.

Colortemperature

A way of describing the color differences in light, measured in Kelvins andusing a scale that ranges from dull red (1,900K), through orange, to yellow,white,andblue(10,000K).

Compression

Technique for reducing the amount of space that a file occupies, by removingredundantdata.

Conjugate

Thedistancebetweenthecenterofthelensandeitherthesubjectorthesensor.

Contrast

Therangeoftonesacrossanimagefrombrighthighlightstodarkshadows.

Cropping

Theprocessofremovingunwantedareasofanimage,leavingbehindthemostsignificantelements.

DeltaE(∆E)

A value representing the amount of change or difference between two colorswithintheCIELABcolorspace.Industryresearchstatesthatadifferenceof6∆Eorlessisgenerallyacceptable.

Depthoffield

Thedistanceinfrontofandbehindthepointoffocusinaphotographinwhichthesceneremainsinacceptablysharpfocus.

Diffusion

Thescatteringoflightbyamaterial,resultinginasofteningofthelightandofanyshadowscast.Diffusionoccursinnaturethroughmistandcloudcover,andcanalsobesimulatedusingdiffusionsheetsandsoft-boxes.SeeSoft-box.

Dynamicrange

A measure of image density from the maximum recorded density to the

minimum, so an imagewith a DMax (maximum density) of 3.1 and a DMin(minimum) of 0.2 would have a dynamic range of 2.9. Dynamic range ismeasuredonalogarithmicscale:anintensityof100:1is2.0,1,000:1is3.0.Theverybestdrumscannerscanachievearound4.0.

Edgelighting

Lightthathitsthesubjectfrombehindandslightlytooneside,creatingflareorabright“rimlighting”effectaroundtheedgesofthesubject.

Extensionrings

An adapter that fits into an SLR between the sensor and the lens, allowingfocusingoncloserobjects.

Extraction

Inimageediting,theprocessofcreatingacut-outselectionfromoneimageforplacementinanother.

Feathering

Inimageediting,thefadingoftheedgeofadigitalimageorselection.

Fileformat

The method of writing and storing information (such as an image) in digitalform.FormatscommonlyusedforphotographsincludeTIFF,BMP,andJPEG.

Filter

(1)Athinsheetoftransparentmaterialplacedoveracameralensorlightsourcetomodifythequalityorcolorofthelightpassingthrough.

(2)A feature in an image-editing application that alters or transforms selectedpixelsforsomekindofvisualeffect.

Focallength

Thedistancebetweentheopticalcenterofalensanditspointoffocuswhenthelensisfocusedoninfinity.

Focalrange

Therangeoverwhichacameraorlensisabletofocusonasubject(forexample,0.5mtoInfinity).

Focus

Theopticalstatewhere thelightraysconvergeonthefilmorCCDtoproducethesharpestimage.

Fringe

In image editing, an unwanted border effect to a selection, where the pixelscombinesomeofthecolorsinsidetheselectionandsomefromthebackground.

f-stop

Thecalibrationoftheaperturesizeofaphotographiclens.

Gamma

Afundamentalpropertyofvideosystemswhichdeterminestheintensityoftheoutput signal relative to the input. When calculating gamma, the maximumpossible input intensity is assigned a value of one, and theminimumpossibleintensity (no input) isassignedavalueofzero.Output iscalculatedby raisinginputtoapowerthatistheinverseofthegammavalue(output=input(1/)).

Graduation

The smoothblendingofone toneor color into another, or from transparent tocoloredinatint.Agraduatedlensfilter,forinstance,mightbedarkononeside,fadingtoclearattheother.

Grayscale

Animagemadeupofasequentialseriesof256graytones,coveringtheentiregamutbetweenblackandwhite.

Halo

A bright line tracing the edge of an image. This is usually an anomaly ofexcessivedigitalprocessingtosharpenorcompressanimage.

Histogram

A map of the distribution of tones in an image, arranged as a graph. The

horizontalaxisgoesfromthedarkesttonestothelightest,whiletheverticalaxisshowsthenumberofpixelsinthatrange.

HMI(HydrargyrumMedium-ArcIodide)

Arecentlydevelopedandpopularlightsourceforphotography.

Hot-shoe

An accessory fitting found on most digital and film SLR cameras and somehigh-endcompactmodels,normallyusedtocontrolanexternalflashunit.

HSB(Hue,Saturation,andBrightness)

Thethreedimensionsofcolor,andthestandardcolormodelusedtoadjustcolorinmanyimage-editingapplications.SeealsoHue,Saturation,andBrightness.

Hue

The pure color defined by position on the color spectrum; what is generallymeantby“color”inlayterms.SeealsoSaturationandBrightness.

Inverter

Adeviceforconvertingdirectcurrentintoalternatingcurrent.

ISO

Aninternationalstandardratingforfilmspeed,withthefilmgettingfasterastherating increases, producing a correct exposurewith less light and/or a shorterexposure. However, higher speed film tends to produce more grain in theexposure.

Kelvin(K)

Used to measure the color of light based on a scale created from the colorchanges that occur when a black object is heated to different temperatures.Normal midday sunlight is considered 5,000K. Lower temperature light (lessthan5,000K)ismoreredoryellow,whilehighertemperaturelightismoreblue.

Lasso

Inimageediting,atoolusedtodrawanoutlinearoundanareaofanimageforthepurposesofselection.

Layer

In imageediting,one levelofan imagefile towhichelements fromthe imagecanbetransferredtoallowthemtobemanipulatedseparately.

Localcontrast

Thecontrastrangefoundinsmallerareasofasceneoranimage.

Luminosity

Thebrightnessofacolor,independentofthehueorsaturation.

Macro

Amodeofferedbysomelensesandcamerasthatenablesthelensorcameratofocusinextremeclose-up.

Mask

In image editing, agrayscale template that hidespart of an image.Oneof themost important tools in editing an image, it is used to limit changes to aparticularareaorprotectpartofanimagefromalteration.

Megapixel

Aratingofresolutionforadigitalcamera,relatedtothenumberofpixelsoutputby theCMOSorCCDsensor.Thehigher themegapixel rating, thehigher theresolutionofimagescreatedbythecamera.

Midtone

The parts of an image that are approximately average in tone, fallingmidwaybetweenthehighlightsandshadows.

Modelinglamp

Smalllampinsomeflashgunsthatgivesalightingpatternsimilartotheflash.

Monobloc

Anall-in-oneflashunitwiththecontrolsandpowersupplybuiltin.Monoblocs

canbesynchronizedtocreatemoreelaboratelightingsetups.

Noise

Randompatternsofsmallspotsonadigitalimagethataregenerallyunwanted,causedbynon-image-formingelectricalsignals.

Pentaprism

Abbreviation for pentagonal roof prism. This prism has a pentagonal cross-section, and is an optical component used in SLR cameras. Light is fullyreflected three times, so that the imagedisplayed in theviewfinder is orientedcorrectly.

Photomicrography

Taking photographs of microscopic objects, typically with a microscope andattachment.

Pixel(PICtureELement)

The smallest unit of a digital image—the square screen dots that make up abitmappedpicture.Eachpixelcarriesaspecifictoneandcolor.

Plug-in

Inimageediting,softwareproducedbyathirdpartyandintendedtosupplementthefeaturesofaprogram.

PPI(pixels-per-inch)

Ameasureofresolutionforabitmappedimage.

Primelens

Onewithafixedfocallength.SeealsoZoomlens.

Rectifier

Adeviceforconvertingalternatingcurrentintodirectcurrent.

Reflector

Anobjectormaterialusedtobounceavailablelightorstudiolightingontothesubject,oftensofteninganddispersingthelightforamoreattractiveendresult.Resampling Changing the resolution of an image either by removing pixels(loweringresolution)oraddingthembyinterpolation(increasingresolution).

Resolution

The level of detail in a digital image, measured in pixels (e.g. 1,024 by 768pixels),lines-per-inch(onamonitor),ordots-per-inch(inahalf-toneimage,e.g.1,200dpi).

RGB(Red,Green,Blue)

Theprimary colors of the additivemodel, used inmonitors and image-editingprograms.

Saturation

Thepurityofacolor,goingfromthelightesttinttothedeepest,mostsaturatedtone.SeealsoHueandBrightness.

Selection

In imageediting,apartofanon-screen image that ischosenanddefinedbyaborderinpreparationformanipulationormovement.

Sensitometer

An instrument for measuring the light sensitivity of film over a range ofexposures.

Shutter

Thedeviceinsideaconventionalcamerathatcontrolsthelengthoftimeduringwhichthefilmisexposedtolight.Manydigitalcamerasdon’thaveashutter,butthe term is still used as shorthand to describe the electronic mechanism thatcontrolsthelengthofexposurefortheCCD.

Shutterspeed

Thetimetheshutter(orelectronicswitch)leavestheCCDorfilmopentolightduringanexposure.

SLR(SingleLensReflex)

Acamerathattransmitsthesameimageviaamirrortothefilmandviewfinder,ensuringthatyougetexactlywhatyouseeintermsoffocusandcomposition.

Snoot

Ataperedbarrelattachedtoalampinordertoconcentratethelightemittedintoaspotlight.

S/Nratio

The ratio between the amplitude of the signal (S) to be received and theamplitudeoftheunwantednoise(N)atagivenpointinareceivingsystem.

Soft-boxAstudiolightingaccessoryconsistingofaflexibleboxthatattachestoa light sourceatoneendandhasadiffusion screenat theother, softening thelightandanyshadowscastbythesubject.

Spotmeter

A specialized lightmeter, or function of the camera lightmeter, that takes anexposurereadingforapreciseareaofascene.

Tonalrange

Therangeoftonalvaluesinanimage.Thehistogramfeatureinanimage-editingapplicationdisplaystonalrange.Whenanimagehasfulltonalrange,pixelswillbe represented across the whole of the histogram. Analyzing variation anddeficiencies in the distribution represented in the histogram is the basis formakingtonalcorrections.

Telephoto

Aphotographic lenswitha long focal length thatenablesdistantobjects tobeenlarged.Thedrawbacksincludebothalimiteddepthoffieldandangleofview.

Transformer

Adevicethatconvertsvariationsofcurrentinaprimarycircuitintovariationsofvoltageandcurrentinasecondarycircuit.

TTL(ThroughTheLens)

Describes metering systems that use the light passing through the lens toevaluateexposuredetails.

Value

Aparticularcolortint.Alsoanumericalvalueassignedtoavariable,parameter,orsymbolthatchangesaccordingtoapplicationandcircumstances.

Whitebalance

Adigitalcameracontrolusedtobalanceexposureandcolorsettingsforartificiallightingtypes.

Zoomlens

Acameralenswithanadjustablefocallengthgiving,ineffect,arangeoflensesin one. Drawbacks compared to a prime lens include a smaller maximum

apertureandincreaseddistortion.SeealsoPrimelens.

the dslr field guide: the essential guide to getting the most from your camera

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