POLICE PHOTOGRAPHY REVIEW NOTES
1. Literal Definition:
The word photography us derivative of two Greek words; phos
which means “light” and graphia meaning “write”. Therefore
photography best translates to “write with light”. (Herschel 1839)
2. Modern definition:
Photography is an art or science which deals of the reproduction of
images through the action of light
Upon sensitized materials, with the aid of camera and its accessories
and the chemical processes involved therein. (Aquino 1972)
3. Technical/Legal Definition:
Modern photography may be defined as any means for the chemical,
thermal, electrical or electronic recording of the images of scenes, or
objects formed by some type of radiant energy, including gamma
rays, x-rays, ultra violet rays, visible light and infrared rays. This
definition is broad enough to include not only the conventional
methods of photography but almost and new process that may
developed. (Scott 1972)
PRINCIPLES OF PHOTOGRAPHY:
A photograph is both mechanical and chemical result of
photography. To produce a photograph, light is needed aside from
sensitized materials (film or paper)
Light radiated of reflected by the subject must reach the film while
all other lights are excluded. The exclusion of all other lights is
achieved by placing the film inside a light tight box (camera).
The effect of light on the film is not visible in the formation of
images of objects. To make it visible, we need or require a chemical
processing of the exposed film called development.
The visual effect of light on the film after development varies with
the quantity or quality of light that reached the emulsion of the film.
Too great in the amount of light will produce a transparent or white
shade after development.
The amount of light reaching the film is dependent upon several
factors like lightning condition, lens opening used, shutter speed used,
filters used, etc.
B) Police Photography
Is an art or science which deals with the study of the principles of
photography, the preparation of photographic evidence, and its
application to police work. (Aquino 1972)
C) Forensic Photography
Is the art or science of photographically documenting a crime
scene and evidence for laboratory examination and analysis for
purposes of court trial.
HISTORICAL EVOLUTION OF FORENSIC PHOTOGRAPHY
A.The Basic components Of Photography
1839-is generally known as a birth year of photography.
William Henry Fox Tablot explained a process he had
invented (calotype) at a royal society of London.
The “Calotype” used paper with its surface fibers
impregnated with light sensitive compounds.
Louis Jacques Mande Daguerre- made a public demonstration
in Paris. The Daguerriotype in collaboration to Joseph
The Daguerreotype formed an image directly on the silver
surface of a metal plate.
With Talbots CALOTYPE the fixation was only partial while
the daguerreotype image were permanent with the use of hypo.
1848 – Abel Niepce de Saint Victor introduced a process of
Important Personalities in Police Photography
*Joseph Nicephore Niepce - 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"
*Louis Jacques Mande Daguerre - invented "Daguerreotype", an
early photograph produced on a silver or silver-covered copper plate.It
formed an image directly on the silver surface of a metal plate.It was a
positive process,thus,it yielded one of a kind images.
*William Henry Fox Talbot - invented a process called calotype, a
photographic process by which a large number of prints could be
produced from a paper negative.Calotype use paper with surface fibers
impregnated with light sensitive compounds.
Calotype vs. Daguerre - fixation in calotype was only partial while
images in daguerreotype were made permanent with the use of
hypo (short for hyposulfite thiosulfate,sodium thiosulfate or a
solution of thiosulfate).
Sodium thiosulfate or hypo is a hygroscopic (readily taken up and
retaining moisture) crystalline salt used especially as a
photographic fixing agent and a reducing or bleaching agent.
*John Frederick William Herchel - coined the term photography and
applied the terms negative and positive to photography.He made
improvements in photographic processes, particularly in inventing the
cyanotype process and variations (such as the chrysotype) the
precursors of the modern blueprint process.
- He discovered sodium thiosulfate to be a solvent of silver halides
in 1819, and informed Talbot and Daguerre of his discovery that this
"hyposulfite of soda" (hypo) could be used as a photographic fixer, to
fix pictures and make them permanent after experimentally applying it
*Richard Leach Maddox - was an English photographer and
physician who invented light weight gelatin negative plates for
photography in 1871.
*Frederick Scott Archer - invented the photographic collodion
process which preceded the modern gelatin emulsion.
Collodion - is a wound dressing material made of nitrated cotton
dissolved in ether and alcohol and other chemicals on sheet of
*George Eastman - founded the Eastman Kodak company and
invented roll film, helping bring photography to the mainstream.
Definition of Terms:
Photography - To write with light,from two Greek words, Phos - light
and Graphia - write.
Police Photography - It is an art or science which deals with the study
of the principles of photography, the reproduction of photographic
evidence, and its application to police work.
Forensic Photography - the art or science of photographically
documenting a crime scene and evidence for laboratory examination
and analysis for purposes of court trial.
1.Take photographs of the following:
g.applicants for clearances
h.military and civilian personnel
j.applicant to possess firearm
k.other physical evidence
2. Conduct comparative examination and analysis of questioned
photographs or pictures to the known photographs.
3. Process color and black and white film, print, reduce and enlarge
4. Reproduce picture and other printed matters.
5. Compose portrait by means of portrait composition.
6. Provides photographic intrusion detection devices.
7. Maintain Rogues Gallery (a collection of pictures of persons
Care and Handling of Camera
- Must be carried using a portable bag or built-in container to avoid
dust and dirt.
- Must be kept dry and avoided contact with water and other liquid
- Must be repaired only by qualified technician.
- Must not be cleaned by oil.
- Must not be fixed without proper equipment and tools to avoid
serious damage on it.
Basic Camera Parts and Functions
Camera is a light-tight box; with a lens to form an image with a shutter
and diaphragm to control the entry of the image; a means of holding a
film to record the image/and a viewer or viewfinder to show
the photographer what the image is.
Camera originated from the term camera obscura. Camera obscura
(Latin veiled chamber ) is an optical device used, for example, in
drawing or for entertainment. It is one of the inventions leading to
photography. The principle can be demonstrated with a box with a hole
in one side (the box may be room-sized, or hangar sized). Light from a
scene passes through the hole and strikes a surface where it is
reproduced, in color, and upside-down. The image's perspective is
accurate. The image can be projected onto paper, which when traced
can produce a highly accurate representation.
1. Light Tight Box. This part of the camera is very essential because
of its capability to exclude all unwanted light that may expose the
sensitized materials or film. It is an enclosure that is devoid of light.
2. Lens. The lens is the only responsible in focusing the rays of light
coming from the subject. It is one of the most important parts of
camera because without lens, it is impossible to form a sharp image
of the film.
3. Film H older. The film holder holds the film firmly inside the
is always located at the opposite side of the lens of the camera.
4.Shutter. The shutter served as the barriers of the rays of light that
will enter and effect the film inside the camera. It is usually placed
at the path of the light passing thru the lens.
Other Parts of the Camera
1. Viewing system
2. Film advancer
3. Shutter speed
4. Lens aperture
5. Focusing mechanism
Major Types of Camera
1.View Finder Type - The smallest and simplest type of camera. This
also known as instamatic camera. View finder camera suffers
2.Single Lens Reflex Type - Cross section view of SLR system
4) Film or sensor
5) Focusing screen
6) Condensing lens
8) Eye piece
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 of parallax error.
Twin Lens Reflex Camera - has two lenses, one for viewing and
focusing on the subject and for taking lens. In this type of camera, the
image to be photographed is seen as flat surface as the image is
reflected by the mirror behind the viewing lens. This suffers parallax
Parallax - the difference between what the view finder on a point and
shoot camera sees and what the lens sees (and thus records on film).At
close shooting distances, the difference can cause you to crop off the
top of a subject's head.
Parallax error - the image you see through the view finder is different
from the image the lens will capture.
VIEW OR PRESS TYPE
5.Film holder/Ground glass
View Or Press Type Camera - The biggest and most sophisticated
among the different type of camera. This type of camera is practically
useless for candid and action photography.
Special Cameras - These are cameras that have been devised that
offer unique advantage or serve special purposes. Among the special
cameras are: a. polaroid, b. panoramic cameras, c. aerial cameras, d.
miniature and ultra-miniature cameras e. digital cameras (using
Control of Cameras:
Knowing the controls on camera is necessary to produce a sharp and
normal image and negatives after photographing. There are three
important controls in a camera to be manipulated and adjusted to its
* Focusing control
* Diaphragm/Aperture control
* Shutter speed
- The camera lens bends light rays to form an image or likeness of the
object. Adjusting the lens to form the clearest possible image is called
focusing. Focusing is defined as the setting of the proper distance in
order to form a sharp image.
Three Types of Focusing
1.Rangefinder Type (e.g. viewfinder, instamatic camera and 35mm
2.Ground Glass Type (e.g. twin-lens reflex camera and digital camera)
3.Scale Bed Type (e.g. press and view camera, and Polaroid Evidence
The rangefinder type is classified into two:
1. Coincidence type - the object to be photographed looks double
the focusing control is not in proper distance, and by moving this
control, one of the objects will move and coincide with the other
to make as one and become accurate appearance of an object.
2. Split Type - Splits the objects to be photographed into two. While
moving the focusing control, the split image will move and unite to
an undivided appearance and therefore the focus is accurate and
Ground Glass Type
Ground glass type focusing mechanism clearly indicates whether the
object distance and the camera is out of focus or not. If the object is
not well focused, the object to be photographed will appear blurred. To
make it clear and accurate the focusing ring of the camera is adjusted
on clockwise or counter clockwise to get the desired clearness of the
Scale-Bed or Focusing Scale
In the scale or bed type focusing mechanism, the distance of the object
to be photographed is calculated by means of feet or meter. There are
cameras where estimated distance from the camera to objects is being
indicated in the focusing ring.
Diaphragm Control (lens opening)
A device called a diaphragm usually serves as the aperture stop, and
controls the aperture. The diaphragm functions much like the iris of the
eye²it controls the effective diameter of the lens opening. Reducing the
aperture size increases the depth of field, which describes the extent to
which subject matter lying closer than or farther from the actual plane
of focus appears to be in focus.
Aperture and shutter speed are the fundamental controls available to
the SLR user: Varying one or other of these opens up a myriad of
creative possibilities. Both also control how much light reaches the
film ± so if you make the hole through which the light passes into the
camera (the aperture) smaller; you must keep this hole open for longer
(the shutter speed) to compensate.
Fortunately, on most cameras this adjustment is made automatically.
The size of the aperture is measured using f/numbers (or f/stops).
Confusingly, as f/numbers represent fractions, the larger the
f/number the smaller the aperture. The widest aperture on a lens might
be f/2, whilst the smallest aperture available may be f/22.
Shutter Speed - is a device that allows light to pass for a determined
period of time, for the purpose of exposing photographic film or a
light-sensitive electronic sensor to light to capture a permanent image
of a scene.
Types of Shutter
1. Central shutters
Central Shutters - are mounted within a lens assembly, or more rarely
behind or even in front of a lens, and shut off the beam of light where
it is narrow. A leaf mechanism is usually used.
Focal Plane Shutter - In camera design, a focal-plane shutter is a type
of photographic shutter that is positioned immediately in front of the
focal plane of the camera, that is, right in front of the photographic
film or image sensor.
Types of Shutters (as to mechanism)
Focal-Plane Shutters - Focal-plane shutters are usually implemented
as a pair of cloth, metal, or plastic curtains which shield the film from
Leaf Shutters - is a type of camera shutter consisting of a mechanism
with one or more pivoting metal leaves which normally does not allow
light through the lens onto the film, but which when triggered opens
the shutter by moving the leaves to uncover the lens for the required
time to make an exposure, then shuts.
Diaphragm Shutters - is a type of leaf shutter consisting of a number
of thin blades which briefly uncover the camera aperture to make the
Central Shutters - is a camera shutter normally located within the lens
assembly where a relatively small opening allows light to cover the
entire image. The term is also used for shutters behind, but near to, the
lens. Interchangeable lens cameras with a central shutter within the
lens body require that each lens has a shutter built into it. In practice
most cameras with interchangeable lenses use a single focal plane
shutter in the camera body for all lenses, while cameras with a fixed
lens use a central shutter. In photography, shutter speed is a common
term used to discuss exposure time, the effective length of time a
shutter is open; the total exposure is proportional to this exposure time,
or duration of light reaching the film or image sensor.
There are many factors to be considered in using this control .
Some of these factors are:
1.The light sensitivity of the film, which are determined through its
2.The lighting condition
3.The motion of the subjects on different angles
4.The purpose of the photographs to be taken, etc.
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 o r 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.
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
T (for time ) - keep the shutter open until the shutter release is
Avoiding Camera Shake
Unless you are using a tripod, the first thing you should ensure when
choosing the shutter speed is that it is fast enough to avoid camera
shake. However tightly you hold your camera, it will always move
slightly as you fire. If you use too slow a shutter speed this will mean
blurred pictures. The speed you use depends on the focal length of lens
you are doing.
How to Hold Your Camera
To be able to use the slowest possible handheld speeds, you must hold
the camera correctly to avoid as much vibration as possible.
Low-level shooting - you don’t always want to take your pictures
normal eye level. This kneeling position allows you to take shots at
When to Use Slow Shutter Speeds
- By using a tripod, or other camera support, photographers can use
slower shutter speeds than usual. These allow you to use apertures that
would not otherwise be possible when using a handheld camera and to
shoot in the lowest light. Slow shutter speeds can also be used for
creative effect, as moving subjects will become artistically blurred.
When to Use Fast Shutter Speeds
Moving subjects require you to consider using a faster shutter speed
than that needed to avoid camera shake. Some blur may be welcome
with action subjects, but often we want to freeze the action. Selecting
the right shutter speed depends not only on the velocity of the subject,
but also on the direction in which it is traveling.
The Lens - A lens is an optical device with perfect or approximate
axial symmetry which transmits and refracts light, converging or
diverging the beam.
Types of Lenses
4. Convex-concave or meniscus
5. Positive or converging lens
6. Negative or diverging lens
Biconvex - A lens is biconvex (or double convex , or just convex ) if
both surfaces are convex.
Biconcave - A lens with two concave surfaces is biconcave (or just
Plano-convex or Plano-concave - If one of the surfaces is flat, the
lens is plano-convex or plano-concave depending on the curvature
of the other surface.
Meniscus - A lens with one convex and one concave side is convex-
concave or meniscus.It is this type of lens that is most commonly used
in corrective lenses.
Positive or Converging Lens - If the lens is biconvex or plano-convex,
a collimated or parallel beam of light traveling parallel to the lens axis
and passing through the lens will be converged (or focused ) to a spot
on the axis, at a certain distance behind the lens (known as the focal
length ). In this case, the lens is called a positive or converging lens.
This lens is always thicker at the center and thinner at the sides. Light
passing through it is bended toward each other on the other side of the
lens meeting at a point. It produces a real image on the opposite side of
the lens or where light is coming from.
Negative or Diverging Lens - If the lens is biconcave or plano-
concave, a collimated beam of light passing through the lens is
diverged(spread); the lens is thus called a negative or diverging lens.
The beam after passing through the lens appears to be emanating from
a particular point on the axis in front of the lens; the distance from this
point to the lens is also known as the focal length, although it is
negative with respect to the focal length of a converging lens.This lens
is always thinner at the center and thicker at the sides. Light passing
through it is bended away from each other as if coming from a point. It
produces a virtual image on the same side of the lens or where light is
Inherent Lens Defects or Aberrations
1. Spherical Aberration
3. Curvature of Field
5. Chromatic Aberration
7. Chromatic Difference of Magnification
Spherical Aberration - When light passing through near the central
part of a converging lens is bended more sharply than those rays
falling in the edge, thus the rays coming from the edges are focused on
a plane nearer the lens than those coming from the central part.
Coma - This is 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. If a lens
has coma, circular objects reproduced at the corners of the negative are
comet-like form. Just like the spherical aberration, it is reduced by
combinations of lenses of different curvatures.
Curvature of Field - This is a kind of defect where 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
Distortion - A lens with distortion is incapable of rendering straight
lines correctly; either horizontal or vertical lines in an object. This is
caused by the placement of the diaphragm. If the diaphragm is placed
in front of the lens,straight lines near the edges of the object tends to
bulge outside. This is known as the barrel distortion.If the diaphragm
is placed behind the lens, straight lines near the edges tends to bend
inward. This isknown as the pincushion distortion. Distortion is
remedied by placing the diaphragm in between the lens component and
the two opposite distortions will neutralize each other.
Chromatic Aberration - This defect is the inability of the lens to bring
photographic rays of different wavelengths to the same focus.
Ultraviolet rays are bent the most while infrared rays are bent to the
least when they pass through the lens. This defect is reduced by
utilizing compound lenses made up of single lens made up of glass of
Astigmatism - This defect is present when 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. In color photography it produces a rainbow colored
fringes around the edges of objects while in black and
white photography, it appears as a slight blue.
Types of Lenses (as to degree of correction to lens aberration)
1. Achromatic lens - corrected for chromatic aberration.
2. Rapid-rectilinear lens - corrected for distortion.
3. Anastigmatic lens - corrected for astigmatism as well as the other
4. Apochromatic lens - also corrected for astigmatism but with higher
degree of correction to color.
Focal length - 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 is a measure of the light-bending power of
a lens. It is invariably measured in millimeters (mm). The longer the
focal length of a lens, the narrower the angle of view , and the larger
objects appear in the viewfinder without the need to move any closer
Focal Distance - is the distance from the optical center of the lens to
the film plane.
Telephotos - are long focal length lenses.
Telephotos are lenses with focal lengths greater than 50mm. They
range from 70mm short telephotos to "long toms" with focal lengths of
1000mm or more.
Wide angles - are short focal lengths.
A lens with a focal length of 50mm is known as a standard lens ± the
view that it gives is similar to that of the human eye . Any lens with a
shorter focal length, and wider angle of view, is known as wide-angle.
How Focal Length Affects Image Size - Lenses work on the principle
that light affecting from a subject can be bent using the
refractive properties of glass to form a miniature image of the subject.
Lenses with short focal lengths, such as the wide-angle lens, produce a
small image. Telephoto lenses, with longer focal lengths, produce a
larger image, when taken from the same distance.
Zoom Lens - It is a kind of lens with variable focal length.
Does Focal Length Affect Depth of Field?
Aperture is not the only factor that affects how much of a scene is in
focus. You should also take into account the focal length of the lens
being used and the distance that the lens is focused at (generally the
distance from the camera to your subject). The longer the focal length,
the more restricted depth of field becomes.So, all things being equal, a
wide-angle lens keeps more of the scene in focus than a telephoto one.
In addition, depth of field becomes increasingly more limited the
closer you are to the subject that your lens is focused on.
Factors Affecting Depth of Field
1. Aperture - The larger the aperture the less depth of field. For
maximum depth of field, use the smallest aperture.
2. Focused Distance - The closer the subject you focus on, the less
of field. Depth of field is greater with distance subjects.
3.vFocal Length - The longer the lens you use, the less depth of field
will have. Wide-angle lenses give the greatest depth of field.
Films and Papers
A.Black and White Films
1.Emulsion - a suspension of a sensitive silver salt or a mixture of
halides in a viscous medium (as a gelatin solution) forming a coating
photographic plates, film, or paper.
2. Gray or Anti-Halation Backing - a layer found in modern
photographic films. It is placed between the light-sensitive emulsion
and the tough film base, or sometimes on the back of the film base.
The light that passes through the emulsion and the base is absorbed
by the opaque anti-halation layer. This keeps that light from
off the pressure plate or anything else behind the film and re-
the emulsion, reducing contrast. The anti-halation layer is rendered
transparent or washed from the film (as in K-14 films) during
of the film.
3.Film Base- A film base is a transparent substrate which acts as a
support medium for the photosensitive emulsion that lies atop it.
Despite the numerous layers and coatings associated with the
layer, the base generally accounts for the vast majority of the
thickness of any given film stock.
Historically there have been three major types of film base in use:
cellulose nitrate,cellulose acetate (cellulose diacetate, cellulose acetate
propionate, cellulose acetate butyrate, andcellulose triacetate), and
polyethylene trephthalate polyester (Kodak trade-name: ESTAR).
Characteristics of B & W Films:
3.Granularity or Graininess
a. ASA (American Standards Association) rating. This is expressed in
b. DIN (Deutsche Industrie Normen) rating, which is expressed in
c. ISO (International Standards Organization) rating. This is expressed
the combined arithmetical and logarithmic values.
a. Blue sensitive film ± sensitive to UV rays and blue color only
b. Orthochromatic film ± sensitive to UV rays, to blue and green color.
It is not sensitive to red color.
c. Panchromatic film ± sensitive to UV radiation to blue, green, and
light or all colors.
d. Infra-red film ± sensitive to UV rays, to blue, green, red light and
Granularity or Graininess
- This refers to the size of the metallic silver grains that are formed
after development of an exposed film. Generally, the size of metallic
silver grains are dependent on the emulsion speed of the film and the
type of developing solution that is used in processing.
Rules to remember:
1.The lower the emulsion speed rating of the film, the finer is the
2. The higher the emulsion speed rating of the film, the bigger are the
3. A film developer will produce a finer grain that a paper developer
used for film processing.
B. Color Films
A color film is a multi-layer emulsion coated on the same support or
Main types of color film in current use
1.Color negative film forms a negative (color-reversed) image when
exposed, which is permanently fixed during developing. This is then
exposed onto photographic paper to form a positive image.
2.Color reversal film, also known as slide film, forms a negative
when exposed, which is reversed to a positive image during
developing. The film can then be projected onto a screen. Ex:
C. Photographic Papers (Black & White)
Photographic paper is exposed to light in a controlled manner, either
by placing a negative in contact with the paper directly to produce a
contact print, by using an enlarger in order to create a latent image, by
exposing in some types of camera to produce a photographic negative,
or by placing objects upon it to produce photograms. Photographic
papers are subsequently developed using the gelatin-silver process to
create a visible image.
Characteristics of a Photographic Paper
1.Chloride paper - has a slow speed and is suited for contact printing.
2. Bromide paper - has a fast speed and is recommended for projection
printing or enlarging.
3. Chloro-bromide paper - is a multi-speed and could be used in both
contact printing and enlarging.
Exposure and development latitude
Latitude is the degree or amount of which you can deviate from the
ideal exposure or development without appreciable loss of print
1. Exposure latitude Generally, photographic papers do not have a
exposure latitude so exposure must be critical at all times.
2. Development latitude Papers that do not change appreciable in
contrast and image tone with reasonable variations in development
has a good latitude. However, for best quality the developing time
should be as near as those prescribed by the manufacturer.
Contrast Range or Grade
In most photographic papers, the contrast range or grade are indicated
by numbers - # 0 to 5
1.#0 and 1 are used on over-exposed or low contrast negative
2.#2 are used on normal exposed or normal contrast negative
3.#3 to 5 used in under-exposed or high contrast negatives
Which Film to Use
Film is available in variety of 'speeds'. The faster the film the more
sensitive it is to light, and the shorter the exposure needed. Fast film
produces a grainier image.Film speed is measured on the ISO scale. A
film rated as ISO 100 is four times slower than an ISO 400film, and
needs four times more light for the same shot.
In photography, a filter is a camera accessory consisting of an optical
filter that can be inserted in the optical path. The filter can be a square
or rectangle shape mounted in a holder accessory, or, more commonly,
a glass or plastic disk with a metal or plastic ring frame, which can be
screwed in front of the lens.
Types of Filters
a. Light Balancing Filter
b. Color Compensating Filter
c. Neutral Density Filter
d. Polarizing Filter
Light Balance Filter - A filter used to change the color quality of the
exposing light in order to secure proper color balance for artificial light
Color Compensating Filter - This is used 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 - This filter is used when the light is too bright
to allow the use of desired f-number or shutter speed with a particular
Polarizing Filter - It is used to reduce or minimize reflections on
subjects like water glass, and highly polished surfaces.
Exposure - is simply a combination of the 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 is subjective and errors in calculation will result to
overexposure or underexposure.
Proper exposure is dependent on:
a. Film speed
b. Lighting condition
c. Type of subject
Light: Its Characteristics and Sources
Light is a form of energy, and to understand light we begin with the
electromagnetic spectrum which is basically a grouping of all
electromagnetic radiation arranged according to the amount of energy
contained in the radiation. Visible light is a part of this electromagnetic
spectrum that creates the sensation of light when it falls on the human
eye. The properties of all electromagnetic radiation can be described
by three inter-related terms. These are wavelength, frequency and
energy. Since light is a part of this spectrum, it too can be described by
these terms. Hence, it is important to understand these terms as a first
step towards understanding light.
Simplistically, we can think of light traveling as a wave. A typical
wave form (e.g., ripples on the surface of water) has crests (or peaks)
and troughs (or valleys). The distance between two consecutive peaks
(or troughs) is called the wavelength, and is denoted by the Greek
letter (lambda).The wavelengths of visible light are measured in
nanometers (nm) where 1 nm = 1 billionth of a meter (10-9 meters).
The wavelength of visible light is between 400-700nm. The combined
effect of the complete range of radiation between 400-700nm appears
as white light to the human eye.
* Violet - 400 to 440nm
* Blue - 440 to 490nm
* Green - 490 to 540nm
* Yellow - 540 to 590nm
* Orange - 600 to 650nm
* Red - 650 to 700nm
4 Photographic Rays of Modern Photography
1.X-Rays - 1 to 30 nm
2.UV Rays - 30 to 400 nm
3.Visible Light - 400 to 700 nm
4.Infrared Rays - 700 to 100 nm
Primary Colors of Light
Secondary Colors of Light
White - is the presence of all color.
Black - is the absence of all colors or the absence of light.
Primary Colors of Coloring Matters
Bending of Light - When traveling in open space, light travels in a
straight line (186,000 miles/second). However, when light comes in
contact with an object, it may be bended in the following manner:
face, it bounces off in all directions due to the
microscopic irregularities of the interface.
* Refraction - It is the change in direction of a wave
due to a change in its speed. This is most commonly observed
a wave passes from one medium to another.
* Diffraction - It is described as the apparent bending of waves
around small obstacles and the spreading out of waves past small
openings.It is also described as the bending of light when it hits a
sharp edge of an opaque object.
Examples of Diffraction
1.The closely spaced tracks on a CD or DVD act as a
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.
Kinds of Objects
1.Transparent objects - allows sufficient visible light to pass through
them that the object on the other side may be clearly seen.
2.Translucent objects - allows light to pass, however diffuse it
sufficiently that objects on the other side may not be clearly
distinguished. In some cases the objects on the other side may be
recognizable but sharp detail and outlines are obscured.
3.Opaque objects - so greatly diffuse the light that recognizing the
object on the other side is very difficult if not impossible.
Sources of Light
1.Natural Light Source
2.Artificial Light Source
Natural Light Source (Sunlight)
1. Bright sunlight - a lighting condition where objects in open space
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
1.Cloudy bright - objects in open space cast no shadow but objects
far distance are clearly visible.
2.Cloudy dull - objects in open space cast not shadow and visibility
distant objects are already limited.
Artificial Light Source - Light sources of this category are man-made
and is divided into the continuous radiation and the short duration.
Forensic Light Sources
2.LASER - Light Amplification through Simulated Emission of
3.Alternative Light Sources
4.Forensic Light Sources
DEVELOPING, PRINTING AND ENLARGING
1.Black & White Processing - development, stop-bath, and fixation.
2.Color Processing - development, stop-fix, and stabilizer
Development - It is the conversion of latent image in an emulsion into
1.B & W Emulsion - reducing exposed silver halide crystals (black
into metallic silver. (Same reaction is found in photographic papers.)
2.Color Emulsion - Developed silver is replaced with cyan, yellow,
Stop-Bath - The 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.
Fixation - The 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. The most
common salts used are sodium thiosulfate - commonly called hypo -
and ammonium thiosulfate, commonly used in modern rapid fixer
Film Processing - It can be carried out in trays, tanks, or mechanized
Panchromatic materials - handled in total darkness.
Blue films, orthochromatic films and printing papers - handled under a
Equipment for Film Processing
1.Tank or tray
3.Opener for film cartridge (pliers)
4.Scissors to cut the tongue of the film
9.Film clips for drying
10.glass or plastic bottles (gallon size) for storing mixed solutions
4.Accelerator or activator
D-76 Film Developer Formula
1.Water 520 C - 750 ml
2.Elon - 2 gm
3.Hydroquinone - 5 gm
4.Sodium Sulfite - 100 gm
5.Borax (granules) - 2 gm
6.Water to make - 1 li
Dektol - Paper Developer
1.Water 520C or 125 0F - 500 m l
2.Elon - 311 gm
3.Hydroquinone - 12 gm
4.Sodium Sulfite - 4.5 gm
5.Sodium carbonate - 67.5 gm
6.Potassium bromide - 1gm
7. Water to make - - 1 li
Stop-Bath - Stop-bath can be plain water only with 28% glacial acetic
Fixing Bath Formula
Typical Fixing Formula:
1.Water 520C or 125 0F - 600 ml
2.Hypo - 240 gm
3.Sodium sulfite - 15 gm(anhydrous)
4.Acetic Acid (28%) - 480 ml
5.Boric Acid (crystals) - 7.5 gm
6.Potassium alum - 15 gm(fine granular
7 Water to make - 1 li
1.Contact Printing - It is a procedure of exposing photographic print
materials while it is pressed in contact with the negative being
2.Projection Printing or Enlarging - It is a type of printing where the
image in a negative is optically projected or enlarged onto a print
material for exposure to produce a picture image. The main
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).
2.Metal, plastic, or bamboo tong preferably with rubber ends to hold
3.Rubber (surgical) hand gloves.
6.A bigger tray or tank for washing prints.
APPLICATION TO POLICE WORK
2.Recording and preserving of evidences
3.Discovering and proving of evidences not readily seen by the naked
4.Recording action of offenders
5.For court exhibits
6.For crime prevention
Forensic photography - sometimes referred to as police photography,
forensic imaging or crime scene photography. - is the art of producing
an accurate reproduction f a crime scene or an accident using
photography for the benefit of a court or to aid in an investigation.
Photography - is the art, science and practice of creating durable
images by recording light. The word photography was derived from
the Greek word "phos" - light and "graphe" - drawing.
Photograph - is an image created by light falling on a light-sensitive
surface usually photographic film or electronic imager.
Sir John Herschel - made the word photography known to the world
in a lecture before the royal society of London on 1839.
Camera - is a device that records and stores images.
History of camera
• Mo Ti - 5th century BC Chinese philosopher who noted that a
pin hole can form an inverted and focused image when light
passes through the hole and into a dark area. He is the first
recorded person to have exploited this phenomenon to trace the
inverted image to create a picture.
• Aristotle - in 4th century BC, described observing a partial solar
eclipse in 330 BC by seeing the image of the sun projected
through the small spaces between the leaves of the tree.
• Ibn Al-Haytham (Alhazen) - an Egyptian scientist who wrote
about observing a solar eclipse through a pin hole and he
described how a sharper image could be produced by making the
opening of the pin hole smaller.
• Roger Bacon - English philosopher and Franciscan friar who in
his study of optics, included a discussion of the physiology of
eyesight, the anatomy of the eyes and brain and considered light,
distance, position, size, direct vision, reflected vision and
refraction, mirrors and lenses.
• Johannes Kepler - a German mathematician and astronomer who
applied the actual name of camera obscura and later added a lens