archaeological photography workshop field archaeology arch1003
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Archaeological Photography Workshop Field Archaeology ARCH1003. Archaeological Photography Objectives. Photo Documentation (Hester 1997) A comprehensive and technical record of an investigation from beginning to end - PowerPoint PPT PresentationTRANSCRIPT
Archaeological Photography Workshop
Field Archaeology ARCH1003
Archaeological Photography Objectives
Photo Documentation (Hester 1997)A comprehensive and technical record of an investigation from beginning to end
Excavation, process of recovering artefacts, sequences, units and profiles, survey finds. It is a historical record
Ethical responsibility of archaeologist to visually record an irreversible process such as excavation or survey. Subsequent analysis or re-analysis of your work in future
Photo Illustration (Hester 1997)To provide images for publication or presentation What are you trying to communicate to the public or in the journal?
Why photograph and illustrate?
Single Lens Reflex (SLR) Camera Features
LensLens apertureFocusing ringAuto AdvanceAperture or AV valueHot shoeShutter speed or TV
(Time Value)
ISO settingShutter releaseFrame counterFocal plane shutterRemote release
socketFilm WindowMirrorPrism
Light
Light is focussed through a lens by refraction (bending of light rays) to form an image behind the lens
To produce a photograph we need:
A light source
An object such as a mirror to reflect the light
A light sensitive medium to record the reflected light (film/digital sensor)
Colour temperature (degrees Kelvin)
Aperture Value
Aperture = f/stop = AV (Pentax camera)
Size of the aperture opening in the lens
A large number (F22) is a small aperture
A small number (F2.8) is a large aperture
To stop down is to reduce the aperture
The f number derives from dividing the focal length (mm) of the lens by the diameter of the aperture
Relationship Between Aperture and Light
Time Value/Shutter Speed
Time Value = shutter speed = TV (Pentax camera)
Length of time the camera shutter opens to expose the film/sensor to the light coming through the lens
1/8 second or slow shutter speed (requires tripod to avoid camera shake)
1/4000 or fast shutter speed (captures water splashing)
Exposure
Exposure is the total amount of light reaching the film calculated from a combination of aperture value (AV) and time value (TV)
Reducing the AV value (or f-stop) from f16 to f22 necessitates doubling the exposure time or TV (time value) for the same exposure result
1/250 second at f22 will give the same exposure result as 1/125 second at f16 (TV reduced but aperture opened up)
Depth of Field
Depth of field is the zone extending in front of and behind the focussed distance within which points will appear to be sharp
The smaller the aperture (AV 22) increases the depth of field
The larger the aperture (AV 5.6) decreases the depth of field
Shorter focal length (wide-angle 28mm) increases depth of field
Longer focal length (telephoto 300mm) decreases depth of field
Focal Length
Light travels in parallel beams and reaches the lens
The distance between the lens and the point at which such light is focussed is the focal length of the lens
It is always expressed in millimetresAn object the same distance away from a long
focal lens will give a larger image than one of short focal length
Standard focal length is 50mm for 35mm camera (negative is 35mm x 24mm)
Angle of View
The angle of view for the human eye is around 45 degrees
Angle of view is the amount of the scene in front of camera taken in by the lens.
A fish eye lens (18mm focal length) will provide 180 degrees angle of view
A telephoto lens (1200mm focal length) will provide 2 degrees
Note: A longer focal length (300mm lens) will decrease the depth of field
Film speed
ISO film speed is the films sensitivity to light rating
The more sensitive the film, the higher the ISO number and the less light required
ISO 6 is a slow, fine grained film and requires a tripod
800 or 1600 ISO is a fast film (newer films not so grainy, used with/without flash)
TMax 3200 can be used with available light at night
Perspective
The apparent distance in the relative sizes of near and far objects
A function of the distance away of the cameraWide angle distortion 28 to 35mm may steepen
the perspective of your trench or structure leading to convergence of lines and aberrations at edge of negative
Standard focal length lens (50mm) or higher will give normal perspective
Telephoto lens (above 50mm) may flatten perspective
Metering
Current Single Lens Reflex (SLRs) cameras have built in metering
Correct Exposure (Pentax) is when the green light is half-way and is changed by adjusting AV/TV values
If positive = overexposedIf negative = underexposedNote: internal meter reads whole scene not just
object unless that fills the frameIncident, reflective, spot metering, grey cards
Camera Handling and Care
Dirt, water, dust, sun can damage cameras and/or precious exposed film
Use bag or waterproof case (e.g. Pelican) for rainy days
Lens tissue for clearer picture. Check the lens!
filters will help protect the lens
Do not over tighten the tripod screw
Batteries may leak if for a long time in the camera
Field Equipment
Scale (range pole and/or centimetre scales)
Additional cameras (black and white, slide and/or colour print, digital)
Photographic proforma or notebook/register
North arrowTripod and remote cable
releaseFlash/Supplementary
Lighting
Film! cards/laptop/burnerBatteriesFiltersSpecial requirements for
digital camerasCamera hood and
waterproof caseReflectors Lens cleaning materialSpecial lenses
General Principles of Archaeological Photography
Technical Photograph descriptive and realistic
Control the lightUse an appropriate scaleA scale should be in the same
plane as the objectViewpoint is critical. Fill the
frame. Use macro lenses/function for small objects
Film/CD media is low cost, while project time is not Exposure is critical
Record on proforma/notebook (Never Later)
Record meaningful information
A changing landscape?Detail, Geology,
construction materials, flora,
Save images to digital archive at highest resolution possible and back up records
Overall Site and Aerial Photographs
The relationship between a site and surroundings is essential. Try to convey a sense of context or environment
Try to take an elevated photograph if possible (wall, ladder, tree, elevating machinery, box
Conventional aerial photographs - planes,
Low-level aerial photographs - booms, balloons, and kites
Photo Illustration
Photo Illustration
Aerial Site OverviewPhoto: David Webb, UK
Critique Photograph
Critique Photograph
Critique Photograph
Critique Photograph
Scale
Scale Position/Use of Negative
Human Scale/Site Context
Scale/Use of Negative/Cleaning
Direct Sunlight/Contrast
Diffuse Light
Overcast Lighting/Scale/Use of Negative
Background Placement, Scale, Glass in Sunlight
Artefact Use Visualization
Finger as Scale
Scale Size/Placement
Scale Placement
IFRAO scale AURA, PO BOX 216, Caufield
South VIC [email protected]
Rock ArtIFRAO scale
Studio Lighting
Studio Lighting