reviewer in police photography
TRANSCRIPT
Reviewer in Police
PhotographyBy
MELCON S. LAPINA, MSCrim4th Place, Criminologists Board Exams, October 1996, Manila
melcon s. lapina, mscrim
melcon s. lapina, mscrim
1. He was able to obtain camera images on papers sensitized with silver chloride solution in 1816. He invented a photographic process which he called “heliography,” meaning “writing of the sun.”a. John Frederick William
Herschelb. Joseph Nicéphore Niépcec. Louis Jacques Mande
Daguerred. William Henry Fox Talbot
invented
ANSWER
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2. The art or science of photographically documenting a crime scene and evidence for laboratory examination and analysis for purposes of court trial.
a. Forensic Photographyb. Modern Photographyc. Police Photographyd. Technical Photography
ANSWER
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3. Literally means dark chamber a. Diaeta aquilus b. Anacleta atramentum c. Thalamus attratus d. Camera obscura
ANSWER
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4. A light tight box, with a means of forming the image (lens), holding sensitized materials (film holder), and with a means of controlling the amount of light that reach the film.
a. Shutter b. Aperture c. Camerad. Lens
ANSWER
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5. The best way to determine the entire coverage of the camera is to look behind the lens of the camera. In this manner, the object can be framed properly and recorded on the film. This type of camera eliminates the problem on parallax error.
a. Single-Lens Reflex b. Twin-Lens Reflex c. Press Type Camera d. Viewfinder TypeANSWE
R
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6. The difference between the image seen by the viewing system and that recorded on the film. Problems occur as the subject moves closer to the taking lens when using Twin-Lens Reflex (TLR) cameras. a. Aberration b. Shutter error c. Diaphragm error d. Parallax error
ANSWER
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7. The object to be photographed looks double when the focusing control is not in proper distance…
a. Coincidenceb. Rangefinderc. Scale-Bed Typed. Split-Type
ANSWER
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8. Functions much like the iris of the eye—it controls the effective diameter of the lens opening.a. Diaphragmb. Focusingc. Shutterd. Lens
ANSWER
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9. A lens with one convex and one concave side is convex-concave.a. Biconcave b. Biconvex c. Meniscusd. Plano-Convex
ANSWER
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10.A lens aberration in which off-axis light rays focus as different distances when they pass through different areas of the lens. a. Astigmatism b. Chromatic aberration c. Spherical aberration d. Coma
ANSWER
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11.Lens with focal lengths greater than 50mm.
11. Standard lens12. Telephoto lens13. Wide-angle lens14. Zoom lens
ANSWER
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12.The material necessary to produce a positive print is
a. Sensitized paper b. Film c. Emulsiond. Filter
ANSWER
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13.A homogenous medium, which absorbs and transmits differentially light rays passing through it.
13. Sensitized paper 14. Filter 15. Film16. Emulsion
ANSWER
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14.A part of this electromagnetic spectrum that creates the sensation of light when it falls on the human eye.
a. Visible light b. UV light c. X-rays d. Infrared light
ANSWER
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15.Objects that caused absorption are
a. Opaque b. Translucent c. Fluorescence d. Transparent
ANSWER
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16.Object in open space casts a deep and uniform shadow
a. rainy sunlight b. bright sunlight c. hazy sunlight d. dull sunlight
ANSWER
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17.The process of removing unexposed silver halides remaining in the emulsion after the first stage of development of the latent image.
a. stop bath b. fixation c. development d. washing and dryingANSWE
R
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18.A developer for film.a. Dektolb. D-76c. Hypod. Glacial acetic acid
ANSWER
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19.The so-called camera in reverse.
a. Contact printerb. Enlargerc. Projectord. Magnifier
ANSWER
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20.Photographs are being used in police work to deter would-be offenders in committing crime.
a. Identification purposesb. Recording actions of
offendersc. For crime preventiond. Public information
ANSWER
melcon s. lapina, mscrim
1. He was able to obtain camera images on papers sensitized with silver chloride solution in 1816. He invented a photographic process which he called “heliography,” meaning “writing of the sun.”a. John Frederick William
Herschelb. Joseph Nicéphore Niépcec. Louis Jacques Mande
Daguerred. William Henry Fox Talbot
invented
PERSONALITY CONTRIBUTION
Joseph Nicéphore Niépce
Heliography – writing of the sun.
Louis Jacques Mande Daguerre
Daguerreotype – photograph on a silver or a silver-covered copper plate; positive image. Fixation is permanent by hypo.
William Henry Fox Talbot
Calotype – paper negative with light sensitive compounds on the surface. Fixation is partial.
John Frederick William Herschel
Coined photography. Applied terms negative and positive to photography.
Frederick Scott Archer Collodion process – preceded the modern gelatin emulsion.
Richard Leach Maddox Lightweight gelatin negative plates
George Eastman Eastman Kodak Company & roll of film
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PERSONALITY CONTRIBUTION
Alhazen Described camera obscura.
JM Petzval Designed the first lens specifically for photographic use
Geronimo Cardano Fitted a biconvex to the camera obscura.
Thomas Sutton Patented the first single-lens reflex.
Vioglander Produced a lens for the use in the first all-metal unitized camera.
Daniel Batbaro Suggested the use of diaphragm to sharpen the image.
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2. The art or science of photographically documenting a crime scene and evidence for laboratory examination and analysis for purposes of court trial.
a. Forensic Photographyb. Modern Photographyc. Police Photographyd. Technical Photography
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DEFINITION OF TERMS
CATEGORY DESCRIPTION
Etymological/Literal
To write with light. Gr. Phos – light & Graphia – write
Modern Definition
Reproduction of images: light, sensitized materials, camera and its accessories, and the chemical processes.
Technical/Legal Chemical, thermal, electrical or electronic recording of the images of scenes, or objects thru XUVI.
Police Photography
Photography applied to police work.
Forensic Photography
Documenting crime scene & evidence for laboratory examination and court trial.
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3. Literally means dark chamber a. Diaeta aquilus b. Anacleta atramentum c. Thalamus attratus d. Camera obscura
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Latin veiled chamber or dark room
An optical device in drawing or entertainment.
CAMERA OBSCURA
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4. A light tight box, with a means of forming the image (lens), holding sensitized materials (film holder), and with a means of controlling the amount of light that reach the film.
a. Shutter b. Aperture c. Camerad. Lens
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Light-tight box – devoid of light Lens – focusing rays of light Film holder Shutter Viewing system Film advancer Shutter speed Lens aperture Focusing mechanism
CAMERA
Other parts
Basic parts
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5. The best way to determine the entire coverage of the camera is to look behind the lens of the camera. In this manner, the object can be framed properly and recorded on the film. This type of camera eliminates the problem on parallax error.
a. Single-Lens Reflex b. Twin-Lens Reflex c. Press Type Camera d. Viewfinder Type
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Type Description
Viewfinder Type Smallest & simplest type; a.k.a. instamatic; suffers parallax error
Single Lens Reflex
Looking behind the lens of the camera; eliminates parallax error
Twin Lens Reflex Type
Two lenses: viewing and focusing lens, & taking lens; suffers parallax error
View or Press Type
Biggest and most sophisticated; not for candid & action photography
Special Cameras Polaroid, panoramic cameras, aerial cameras, miniature and ultra-miniature cameras, digital cameras
Major Types of Camera
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6. The difference between the image seen by the viewing system and that recorded on the film. Problems occur as the subject moves closer to the taking lens when using Twin-Lens Reflex (TLR) cameras. a. Aberration b. Shutter error c. Diaphragm error d. Parallax errorProceed to Next Question
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7. The object to be photographed looks double when the focusing control is not in proper distance…
a. Coincidenceb. Rangefinderc. Scale-Bed Typed. Split-Type
This topic discusses about control of camera.
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Type Description Focusing Setting of proper
distance in order to form sharp image.
Diaphragm
Usu. serves as aperture stop, & controls aperture; like iris of eye.
Shutter Barriers of rays of light
Control of Camera
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Control of Camera
Type Description
Rangefinder Type
For viewfinder, instamatic camera and 35mm cameras: 1. coincidence – object appears double when out of focus; 2. split – object appears split when out of focus.
Ground Glass Type
Object appears blurred when out of focus.
Scale Bed Type
Focusing is made by calculating or estimating the distance of object to be photographed. Focusing ring is adjusted to corresponding estimated distance.
Three Types of Focusing
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8. Functions much like the iris of the eye—it controls the effective diameter of the lens opening.a. Diaphragmb. Focusingc. Shutterd. Lens
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Diaphragm
Characteristics:
A.k.a. Lens Opening or Aperture
Size of aperture: measured by f/numbers or f/stops
Ratio of f/# to aperture: larger number of f/# : smaller aperture.
Small aperture: increased depth of field – nearest and farthest object in the same sharpness.
Control of Camera
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Shutter
CharacteristicsAllows light to pass for a determined period of time.Purpose: Expose photographic film, light-sensitive electronic sensor to light.Shutter Speed. About exposure time, the effective length of time a shutter is open.
Control of Camera
There are factors to consider in using this control.
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Shutter is expressed in a fraction of a second. The different shutter speeds are:
1, 2 or 1/2 sec, 4 or 1/4 sec, 8 or 1/8 sec, 15 or 1/15 sec, 30 or 1/30 sec, 60 or 1/60 sec, 125 or 1/125 sec, 250 or 1/250, 500 or 1/500 sec, 1000 or 1/1000, 2000 or 1/2000.
Control of Camera
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Camera shutters often include one or two other settings for making very long exposures:
B (for bulb) — keep the shutter open as long as the shutter release is held.
T (for time) — keep the shutter open until the shutter release is pressed again.melcon s. lapina, mscrim
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Both control the amount of light reaching the film.
Aperture Shutter SpeedLens opening Time shutter is
openSmaller opening Longer time
Exposure: Aperture & Shutter Speed
COMPENSATION
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As discussed, exposure is the combination of aperture and shutter speed. Thus, it is defined as the product of the total light intensity and the length of time it strikes the emulsion. Exposure priority refers to giving precedence of particular camera control – aperture or shutter – over the other depending on the purpose of the photographer. Ex. Aperture priority – photographer sets first the aperture and adjusts the shutter speed to compensate.
Exposure Priority
Aperture Priority
Purpose Aperture
Shutter Speed
Result
Show entire scene
Small Slow Good depth of field.
Select or highlight particular object in scene
Big Fast Object selected – sharply focused. Foreground and background – poor.
Shutter Speed Priority
Purpose Shutter Speed
Aperture Result
Maximizing sharpness
Slow Small Much of scene is sharp.
Taking nightscapes
Very slow Very small Cityscapes at night are clearly seen using available light.
Freezing action in mid-air
Fast Big Action is frozen.
Maximizing Sharpness
NightscapesFrozen in Mid-Air
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9. A lens with one convex and one concave side is convex-concave.a. Biconcave b. Biconvex c. Meniscusd. Plano-Convex
This topic discusses about LENS.
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A lens is an optical device with perfect or approximate axial symmetry which transmits and refracts light, converging or diverging the beam.
The Lens
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10.A lens aberration in which off-axis light rays focus as different distances when they pass through different areas of the lens. a. Astigmatism b. Chromatic aberration c. Spherical aberration d. Coma
This topic discusses about inherent lens defects or aberrations.
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Defect Description
Spherical aberration
Light passing through near the central part of a converging lens is bended more sharply than those rays falling in the edge.
The rays coming from the edges are focused on a plane nearer the lens than those coming from the central part.
Lens Aberrations
Defect Description
Coma
Another form of spherical aberration but is concerned with the light rays entering the lens obliquely.
The defect is noticeable only on the outer edges and not on the central part of the lens.
Circular objects reproduced at the corners of the negative are comet-like form.
Defect Description
Curvature of Field
The image formed by a lens comes to a sharper focus in curved surface than a flat surface.
The correction of this defect is similar to spherical aberration and coma.
Defect Description
Distortion
Incapable of rendering straight lines correctly – either horizontal or vertical lines in an object.
Caused by the placement of the diaphragm.
Barrel distortion - If the diaphragm is placed in front of the lens, straight lines near the edges of the object tends to bulge outside.
Pincushion distortion – If the diaphragm is placed behind the lens, straight lines near the edges tends to bend inward.
Remedied by placing the diaphragm in between the lens component and the two opposite distortions will neutralize each other.
Barrel Distortion
Defect Description
Chromatic Aberration
The inability of the lens to bring photographic rays of different wavelengths to the same focus.
Ultraviolet rays – bent the most Infrared rays – bent the least
Reduced by utilizing compound lenses made up of single lens made up of glass of different curvatures.
Defect Description
Astigmatism
The size of image produced by photographic rays of one wavelength is different from the size produced by another.
Size of the image increases as the wavelength of the rays decreases.
Color photography – rainbow colored fringes around edges of objects B&W Photography – slight blue. Classic example of astigmatism. Left
wheel: no astigmatism. In the presence of astigmatism (middle and right wheels) one discriminates between the sagittal and tangential foci.
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Types of Lenses (accdg to degree of correction to lens aberration)
Type Description
Achromatic lens corrected for chromatic aberration
Rapid-rectilinear lens
corrected for distortion
Anastigmat lens corrected for astigmatism as well as the other lens defects
Apochromatic lens also corrected for astigmatism but with higher degree of correction to color
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11.Lens with focal lengths greater than 50mm.
a. Standard lensb. Telephoto lensc. Wide-angle lensd. Zoom lens
This topic discusses about focal length.
Focal Length
It is the distance measured from the optical center of the lens to the film plane when the lens is set or focused at infinity position or far distance.
Focal Length
Characteristics
Measure of the light-bending power of a lens.
Measured in millimeters (mm).
Longer focal length
- Narrower the angle of view
- Larger the objects appear in the viewfinder without need to
go move closer.
Focal Length
Type Characteristics
Standard 50mm
View that it gives is similar to that of human eye.
Wide-Angle
Shorter focal length
Wider angle of view
Telephoto
Greater than 50mm
Narrower angle of view
Zoom Lens
Variable focal length
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Factors Affecting Depth of Field
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12.The material necessary to produce a positive print is
a. Sensitized paper b. Film c. Emulsiond. Filter
This topic discusses about films and papers
Two General Types of Films
Black & White
Emulsion Gray/Anti-Halation BackingFilm Base
Color Film
Multi-layer emulsion coated on the same support or base.
Emulsion
a suspension of a sensitive silver salt or a mixture of silver halides in a viscous medium (as a gelatin solution) forming a coating on photographic plates, film, or paper.
Gray
Placed between the light-sensitive emulsion and the tough film base, or sometimes on the back of the film base.
Absorbs light by and into opaque anti-halation layer.
Prevents re-exposing of film
Being washed from film during processing.
Film Base
Transparent substrateSupport medium for the photosensitive emulsion atop it.Accounts for the thickness of film.Types: cellulose nitrate, cellulose acetate and polyethylene trephthalate polyester (Kodak trade-name: ESTAR)
Characteristics of B & W FilmsEmulsion Speed
Spectral Sensitivity
Granularity or Graininess
Emulsion Speed
ASA (American Standards Association) rating. This is expressed in arithmetical value.
DIN (Deutsche Industrie Normen) rating, which is expressed in logarithmic value.
ISO (International Standards Organization) rating. This is expressed in the combined arithmetical and logarithmic values.
Spectral Sensitivity
Blue sensitive film – sensitive to UV rays and blue color only
Orthochromatic film – sensitive to UV rays, to blue and green color. It is not sensitive to red color.
Panchromatic film – sensitive to UV radiation to blue, green, and red light or all colors.
Infra-red film – sensitive to UV rays, to blue, green, red light and infrared rays.
Granularity: size of metallic silver grains that are formed after development of an exposed film.
Points to rememb
er
Lower emulsion speed, finer grains.Higher emulsion speed, bigger grainsFilm developer – finer grain Paper developer – bigger grain
Main Types of Color Film
Color negative film
Forms a negative (color-reversed) image when exposed
Permanently exposed during developing
E.g. Kodacolor
Color reversal film
A.k.a. slide film
Forms a negative image when exposed
Reversed to a positive image during developing
Projected onto a screen.
E.g. Kodachrome
Ways of Exposing Photographic Paper
Contact printing Placing negative in contact with paper directly to produce contact print
Enlarging Using enlarger in order to create latent image
Exposing in specialized camera
Producing photographic negative
Photograms Placing objects upon it
Photographic papers are subsequently developed using the gelatin-silver process to create a visible image.
Characteristics of a Photographic Paper
Chloride paper
has a slow speed and is suited for contact printing.
Bromide paper
has a fast speed and is recommended for projection printing or enlarging.
Chloro-bromide paper
is a multi-speed and could be used in both contact printing and enlarging.
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13.A homogenous medium, which absorbs and transmits differentially light rays passing through it.
a. Sensitized paper b. Filter c. Filmd. Emulsion
FILTERS
TYPES OF FILTERS
Light Balance Filter
to change the color quality of the exposing light in order to secure proper color balance for artificial light films.
Color Compensating Filter
to change the over-all color balance of photographic result obtained with color films and to compensate for deficiencies in the quality of exposing energy.
Neutral Density Filter
when the light is too bright to allow the use of desired f-number or shutter speed with a particular film.
Polarizing Filter
to reduce or minimize reflections on subjects like water glass, and highly polished surfaces.
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14.A part of this electromagnetic spectrum that creates the sensation of light when it falls on the human eye.
a. Visible light b. UV light c. X-rays d. Infrared light
Light: Its Characteristics & Sources
Light is a form of electromagnetic energy that can be explained in the following: wavelength, frequency and energy.
Wavelength
Light is traveling like a wave, e.g. ripples in surface of water.Parts: 1. Crests – peaks, 2. Troughs – valleys Wavelength – distance between two consecutive peaks (or troughs)Greek symbol: letter λ (lambda)
Visible Light
Measured in nanometers; 1nm = 1 billionth of meter (10-9 meters).400 – 700 nm
Rainbow ColorsViolet 400 to 440nm Blue 440 to 490nm Green 490 to 540nm Yellow 540 to 590nm Orange 600 to 650nm Red 650 to 700nm
Photographic Rays of Modern Photography
X-rays 1 to 30 nmUltra-Violet Rays
30 to 400 nm
Visible Light 400 to 700 nm
Infrared Rays
700 to 1,000+nm
White is the presence of all colors.Black is the absence of all colors or the absence of light.
Light travels in a straight line at 186,000 miles/second. However, when light comes in contact with an object, it may be bended in the following manner:
BENDING OF LIGHT
Type Subtype Description
Reflection
Specular or Regular Reflection
Reflecting surface – very smooth
Diffuse or Irregular Reflection
Reflecting surface – rough or granular
Refraction
Change in direction of wave due to change in speed
Observed when wave passes from one medium to another
Diffraction
Apparent bending of waves around small obstacles and spreading out of waves past small openings.
Bending of light when it hits sharp edge of opaque object.
Specular or Regular Reflection
Diffuse or Irregular Reflection
The straw seems to be broken, due to refraction of light as it emerges into the air.
Examples of Diffraction1.The closely spaced tracks on
a CD or DVD act as a diffraction grating to form the familiar rainbow pattern we see when looking at a disk;
2.The hologram (a picture that changes when looked at from different angles) on a credit card;
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15.Objects that caused absorption are
a. Opaque b. Translucent c. Fluorescence d. Transparent
This topic talks about the different kinds of objects that light may come in contact with.
Kinds of Objects
Kind Description
Transparent objects
Allows light to pass through; object on the other side may be clearly seen.
Translucent objects
Allows light to pass but sufficiently diffused; objects on the other side may not be clearly distinguished. Some may be recognizable but detail and outline are obscured.
Opaque objects
Greatly diffuse the light; the object on the other side is very difficult if not impossible.
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16.Object in open space casts a deep and uniform shadow
a. rainy sunlight b. bright sunlight c. hazy sunlight d. dull sunlight
This topic discusses about SOURCES OF LIGHT.
SOURCES OF LIGHT
1.Natural Light Source
Moonlight, lightning, starlight, sunlight, etc.
2.Artificial Light Source
Man-made; divided into: 1. continuous radiation and 2. short duration.
Natural Light Source (by Sunlight)1.Bright
Sunlight Objects in open space cast a deep and uniform or distinct shadow.
2.Hazy Sunlight
Objects in open space cast a transparent shadow.
3.Dull Sunlight
Objects in open space cast no shadow.
Types of Dull Sunlight1.Cloudy
bright Objects in open space cast no shadow but objects at far distance are clearly visible.
2.Cloudy dull
Objects in open space cast not shadow and visibility of distant objects are already limited.
Artificial Light SourceArtificial light sources most
useful to police work are FORENSIC LIGHT SOURCES.
FORENSIC LIGHT SOURCES1.UV Lamp2.LASER – Light Amplification
through Simulated Emission of Radiation.
3.Alternative Light Sources4.Alternative Light Sources
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17.The process of removing unexposed silver halides remaining in the emulsion after the first stage of development of the latent image.
a. stop bath b. fixation c. development d. washing and drying
This topic discusses about CHEMICAL PROCESSING of FILM.
Chemical Processing of Film1.Black & White
Processing Development, stop-bath, and fixation.
2.Color Processing
Development, stop-fix, and stabilizer.
Development – the conversion of latent image in an emulsion into visible image.
DEVELOPMENT
1.B & W Emulsion
Reducing exposed silver halide crystals (black silver) into metallic silver. (Same reaction is found in photographic papers.)
2.Color Emulsion
Developed silver is replaced with cyan, yellow, and magenta dye.
STOP-BATHThe purpose of the stop bath is to halt the development of the film, plate, or paper by either washing off the developing chemical or neutralizing it.
FIXATIONThe fixer removes the unexposed silver halide remaining on the Photographic film or photographic paper, leaving behind the reduced metallic silver that forms the image, making it insensitive to further action by light. Without fixing, the remaining silver halide would quickly darken and cause severe fogging of the image.
Salts Used in FixationThe most common salts
used are sodium thiosulfate - commonly called hypo - and ammonium thiosulfate, commonly used in modern rapid fixer formula.
Film Processing: How DoneCarried out in trays, tanks, or mechanized equipment.Panchromatic materials – handled in total darkness.Blue films, orthochromatic films and printing papers – handled under a safelight.
Equipment for Film Processing
a.Tank or tray f. Timer
b.Developing reel g.Funnel
c.Opener for film cartridge (pliers)
h.Photographic sponge
d.Scissors to cut the tongue of the film
i. Film clips for drying
e.Thermometer j. glass or plastic bottles (gallon size) for storing mixed solutions.Proceed to Next Question
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18.A developer for film.a. Dektolb. D-76c. Hypod. Glacial acetic acid
This takes up the formulation of developer, stop-bath and fixer.
Typical Component of Developer:1.Solvent (water)2.Developing agent3.Preservative4.Accelerator or activator5.Restrainer
D-76 Film Developer formula1. Water 520C or 125 0F -750 ml2. Elon -
2 gm3. Hydroquinone - 5 gm4. Sodium Sulfite -100 gm5. Borax (granules) -
2 gm6. Water to make - 1 li
DEKTOL – Paper Developer1. Water 520C or 125 0F -500 ml2. Elon -
311 gm3. Hydroquinone - 12 gm4. Sodium Sulfite - 4.5 gm5. Sodium carbonate -
67.5 gm6. Potassium bromide - 1 gm7. Water to make - 1 li
STOP-BATHStop-bath can be plain
water only with 28% glacial acetic acid.
FIXING BATH FORMULA1. Water2. Dissolving agent3. Preservative4. Neutralizers5. Hardeners
Typical Fixing Formula:1. Water 520C or 125 0F -600 ml2. Hypo -
240 gm3. Sodium sulfite -
15 gm(anhydrous)
4. Acetic Acid (28%) -480 ml5. Boric Acid (crystals)-
7.5 gm6. Potassium alum - 15 gm
(fine granular)7. Water to make -
1 li
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19.The so-called camera in reverse.
a. Contact printerb. Enlargerc. Projectord. Magnifier
This topic deals with photographic printing.
Types of Photographic Printing
1.Contact Printing
Photographic materials are exposed by pressing in contact with the negative being reproduced.
2.Projection Printing or Enlarging
The image in a negative is optically projected or enlarged onto a print material for exposure to produce a picture image. The main equipment is Enlarger, the so-called camera in reverse.
EQUIPMENT FOR PAPER DEVELOPING
1. Three plastic trays – one each for the developer, stop-bath, and the fixer. (The size of the tray is determined by the largest prints size).
4. Timers
2. Metal, plastic, or bamboo tong preferably with rubber ends to hold the prints.
5. Paper cutter
3. Rubber (surgical) hand gloves.
6. A bigger tray or tank for washing prints.
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20.Photographs are being used in police work to deter would-be offenders in committing crime.
a. Identification purposesb. Recording actions of
offendersc. For crime preventiond. Public information
This topic discusses about application of photography to police work.
GENERAL APPLICATION
1.Identification purposes
5.For court exhibits
2.Recording and preserving of evidences
6.For crime prevention
3.Discovering and proving of evidences not readily seen by the naked eye.
7.Public information
4.Recording action of offenders
8.Police training
SPECIFIC APPLICATIONS1.Identification Photographs2.Crime-Scene Photography
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CRIME SCENE
PHOTOGRAPHYWhat crime scene
photography can give: It seeks to establish a visual
record of the condition of the scene and the items present in it.
It leads the viewer from the overall perspective to the details of specific objects.
A crime scene photo log helps eliminate the following issues: Identification, Orientation, and Confusion Issues
Crime Scene Photo Log It is a written record of
photos, detailing: Administrative data. What time the photos were
taken and in what order. What they show. Other pertinent details as
deemed necessary.
Crime Scene Photo Log
Crime Scene Photo LogCase #: 02-01-0045 Date: January 13, 2002
Camera Used: Nikon F2a Time: 1830-1940 HrsFilm Type: ASA 400 Scene: 3567 Wayland Dr.Photographer: SA Brown Film Roll #: 1
Types of Crime Scene Photographs
Over-all PhotographsEvidence Establishing
PhotographsEvidence Close-Up
Phtographs
Overall Photographs
Characteristics
1. Exposed with wide-angle lens
4. Typically taken by shooting from the four corners of the crime scene.
2. Documents the condition and layout of the scene as found.
5. These four photographs will often capture the entire scene.
3. Eliminate issues of subsequent contamination (e.g. tracked blood, movement of items).
6. Photographs from vantage point can be taken if four photographs are not sufficient.
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Shooting the Four Corners
Crime Scene
Photo # 1
Photo # 2
Photo # 3
Photo # 4
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Overall Photo #1
Overall Photo #2
Overall Photograph Example
Overall Photo #3
Overall Photo #4
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Characteristics
1.Typically exposed with a 50mm lens.
4.Most overlooked photograph in crime scene work.
2.Frames the item of evidence with an easily recognized landmark.
5.It is not intended to show details, simply to frame the item with a known landmark in the scene.
3.Visually establishes the position of the evidence in the scene.
6.It goes hand in hand with close-up photograph.
Evidence Establishing Photos
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Use of Establishing Photo
Where is this item in the scene?
The blue background by itself might indicate a number of locations.
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Evidence Establishing Example
Evidence EstablishingPhotograph
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Evidence Close-up Photographs
Evidence close-up photographs are exposed with a "macro" lens (50mm, 55mm or 105mm).
Their function is to allow the viewer to see all evident detail on the item of evidence.
You have to get close and fill the frame with the evidence itself.
They are taken with and without a scale.
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Evidence Close-up Example
Taken both with and without a scale of reference.
Get close and fill the frame of the camera.
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Very important when taking photos of small items, whose detail may affect another analysis.
Ensure a good focus, make the picture sharp.
Evidence Close-up Example
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Photograph Methodology
1. Document the entire scene in-situ as soon as possible using overall photographs.
2. Photograph all fragile evidence as soon as possible.
3. In the documentation stage, photograph all known evidence using evidence establishing and evidence close-up photos.
4. As items are discovered in later stages, return and document them fully, including additional overall photographs if needed.
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Photograph Methodology
5. Create photographs that fully demonstrate the results of additional examinations (e.g. latent prints, bloodstain pattern analysis, trajectory analysis).
6. Always use a film roll reference card on the first shot of each roll to demonstrate admin data.
7. Always use a crime scene photo log.
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1. Chromatic Difference of Magnification – The inability of the lens to produce image sizes of objects with different colors.
2. Depth of Focus – It is the distance toward and away from the film that the lens can be moved at a given f-value and the object still appears in interior.
Some Important Terms
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3. Hyperfocal Distance – The nearest space at which a lens is focused with a given particular diaphragm opening which will give the maximum depth of field.
4. Macrophotography – The photography of a subject so that the final image is either unmagnified or magnified to no more than 10 times the object.
Some Important Terms
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Some Important Terms
5. Microphotography – It is the facsimile of photographs in which the image of an object is reproduced much smaller than it actually is.
6. Photomicrography – Photography showing initial magnifications when the camera is used in relation with a microscope.
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7. Photomacrography – Making large pictures of small subjects by using a short-focal-length lens on a long-bellows camera.
8. Relative Aperture – The light gathering power of the lens, expressed in the F-number system.
Some Important Terms