Photography

Literal Definition: To write with light. From 2 Greek words:phos – light andgraphi a – write.

Modern Definition: It is an art or science which deals with the reproduction of images through the action of light, upon sensitized materials, with the aid of a camera and its accessories, and the chemical processes involved therein.

Photography

Technical/Legal Definition: It is any means for 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.

Technical/Legal Definition: This definition is broad enough to include not only the conventional methods of photography but almost any new process that may be developed.

Police Photography – 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.

Basic Camera Parts and Functions

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 Holder . The film holder holds the film firmly inside the camera. It 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

Major Types of Camera

1.Viewfinder type.2.Single Lens Reflex.3.Twin Lens Reflex Type.

4. View or Press Type. 5.Special Cameras.

Major Types of Camera cont…

Viewfinder Type = The smallest and simplest type of camera. This is also known as instamatic camera. Viewfinder camera suffersparallax error. Single-Lens Reflex Type = 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.

Twin Lens Reflex Camera – 2 lenses: 1. for viewing & focusing of the subject, & 2. 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 also parallax error.

Parallax – The difference between what the viewfinder on a point-and-shoot camera sees and what the lens sees (and thus records on film). At close shooting distances, this difference can cause you to crop off the top of a subject’s head.

Parallax error – The image you see through the viewfinder is different from the image the lens will capture.

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 computer processing)

3 Important Controls of Camera

FOCUSING CONTROL. 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 Rangefinder Type (e.g. viewfinder, instamatic camera and 35mm cameras) Ground Glass Type (e.g. twin-lens reflex camera and digital camera) Scale Bed Type (e.g. press and view camera, and Polaroid Evidence Camera)

Rangefinder Type The rangefinder type is classified into two: Coincidence type – the object to be photographed looks double when the focusing control is not in proper distance, and by moving this control, one of the objects will move and coincide with the other object to make as one and become accurate appearance of an object. Split Type – Splits the objects to be photographed into two. While moving the focusing control, the split image will move and unite to form an undivided appearance and therefore the focus is accurate and perfect.

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 object.

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 eye—it 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.

SHUTTER SPEED. Shutter 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. There are many factors to be considered in using this control. Some of these factors are:

The light sensitivity of the film, which are determined through its ISO; The lighting condition; The motion of the subjects on different angles; and The purpose of the photographs to be taken, etc.

Types of Lenses1. Biconvex2. Biconcave3. Plano-convex/plano-concave4. Convex-concave or meniscus5. Positive or converging lens6. Negative or diverging lens

Inherent Lens Defects or Aberrations1. Spherical Aberration2. Coma3. Curvature of Field4. Distortion5. Chromatic Aberration6. Astigmatism7. 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 coma.

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 is known 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 different curvatures.

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. Anastigmat lens – corrected for astigmatism as well as the other lens defects. 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 distance is the distance from the optical center of the lens to the film plane.

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 to them. Long focal length lenses are called telephotos – short focal lengths are called wide angles.

Wide-angles 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.

Telephoto 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.

Zoom Lens It is a kind of lens with variable focal length.

A. BLACK & WHITE FILMS 1. 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. 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 reflecting off the pressure plate or anything else behind the film and re- exposing the emulsion, reducing contrast. The anti- halation layer is rendered transparent or washed from the film (as in K-14 films) during processing 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 emulsion 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, and cellulose triacetate), and polyethylene trephthalate polyester (Kodak trade- name: ESTAR).

Characteristics of B & W Films: 1. Emulsion Speed 2. Spectral Sensitivity 3. Granularity or Graininess

Emulsion Speed a. ASA (American Standards Association) rating. This is expressed in arithmetical value. b. DIN (Deutsche Industrie Normen) rating, which is expressed in logarithmic value. c. ISO (International Standards Organization) rating. This is expressed in the combined arithmetical and logarithmic values.

Spectral Sensitivity 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 red light or all colors. d. Infra-red film – sensitive to UV rays, to blue, green, red light and infrared rays.

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 grain. 2. The higher the emulsion speed rating of the film, the bigger are the grains. 3. A film developer will produce a finer grain that a paper developer when used for film processing.

B. COLOR FILMS A color film is a multi-layer emulsion coated on the same support or base. Main types of color film in current use 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. Ex: Kodacolor Color reversal film, also known as slide film, forms a negative image when exposed, which is reversed to a positive image during developing. The film can then be projected onto a screen. Ex: Kodachrome

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.

TYPES OF FILTERSa. Light Balancing Filterb. Color Compensating Filterc. 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 films.

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 film.

Polarizing Filter It is used to reduce or minimize reflections on subjects like water glass, and highly polished surfaces.

Light: Its Characteristics & 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.

Rainbow Colors:

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

X-rays – 1 to 30 nm

UV rays – 30 to 400 nm

Visible light – 400 to 700 nm

Infrared rays – 700 to 1,000+ nm.

PRIMARY COLORS OF LIGHT

R ed

Green

Blue

SECONDARY COLORS OF LIGHT

Yel l o w

C y an

M ag en t a

NOTE: 1. White is the presence of all colors 2. Black is the absence of all colors or the absence of light.

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:

Reflection of Light

1.Specular or Regular Reflection - If the reflecting surface is very smooth, the reflection of light that occurs is called specular or regular reflection. 2.Diffuse or Irregular Reflection – When light strikes a rough or granular surface, 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 when 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.

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 outline 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 Light1. Natural Light Source2. Artificial Light Source

Natural Light Source (Sunlight)

1. Bright sunlight – a lighting condition where 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.

a. Cloudy bright – objects in open space cast no shadow but objects at far distance are clearly visible.

b. Cloudy dull – objects in open space cast not shadow and visibility of 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 1. UV Lamp 2. LASER – Light Amplification through Simulated Emission of Radiation.3. Alternative Light Sources4. Forensic Light Sources

CHEMICAL PROCESSING 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 visible image.

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.

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 rapi d fixer formula.

FILM PROCESSING It can be carried out in trays, tanks, or mechanized equipment.

NOTE:Panchromatic materials – handled in total darkness.Blue films, orthochromatic films and printing papers – handled under a safelight.

Equipment for Film Processinga. Tank or tray

b. Developing reelc. Opener for film cartridge (pliers)d. Scissors to cut the tongue of the filme. Thermometerf. Timerg. Funnelh. Photographic spongei. Film clips for drying

j. glass or plastic bottles (gallon size) for storing mixed solutions.

DEVELOPER FORMULATIONTypical component:1. Solvent (water) 2. Developing agent

3. Preservative4. Accelerator or activator5. Restrainer

D-76 Film Developer formula 1. Water 520C or 125 0F - 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 ml 2. Elon - 311 gm 3. Hydroquinone - 12 gm 4. Sodium Sulfite - 4.5 gm 5. Sodium carbonate - 67.5 gm 6. Potassium bromide - 1 gm 7. Water to make - 1 li

STOP-BATH Stop-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 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 PHOTOGRAPHIC PRINTING 1. Contact Printing 2. Projection Printing or Enlarging Contact Printing

It is a procedure of exposing photographic printmaterials while it is pressed in contact with the negative beingreproduced.

Projection Printing or Enlarging

It is a type of printing where the image in a negativeis optically projected or enlarged onto a print material forexposure to produce a picture image. The main equipment isEnlarger, 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 the prints.

3. Rubber (surgical) hand gloves.

4. Timers

5. Paper cutter

6. A bigger tray or tank for washing prints.

GENERAL APPLICATION

Identification purposes

Recording and preserving of evidences

Discovering and proving of evidences not readily seen by the naked eye.

Recording action of offenders

For court exhibits

For crime prevention

Public information

Police training

SPECIFIC APPLICATIONS 1. Identification Photographs 2. Crime-Scene Photography