POLICE PHOTOGRAPHY Mr. Bayani H. Salamanca Dean, College of Criminology Araullo University PHINMA Education Network POLICE PHOTOGRAPHY is an art or science that deals with the study of the principles of photography, the preparation of the photographic evidence, and its application to police work. PHOTOGRAPHY IN CRIMINAL INVESTIGATION Photography is an essential tool for the law-enforcement investigator. As a tool, it enables him to record the visible and in many cases, the invisible evidences of a crime. Special techniques employing infrared, ultra-violet, and X-ray radiation enable him to record evidence, which is not visible. The photographic evidence can then be stored indefinitely and retrieved when needed. There is no other process, which can ferret, record, remember and recall criminal evidence as well as photography. Photographs are also a means of communication. It is a language sometimes defined as the “most universal of all languages”. Photography has an advantage as a language because it does not rely upon abstract symbols-words. Photography thus is more direct and less subject to misunderstanding. A. FUNCTIONS OF PHOTOGRAPHY IN INVESTIGATIVE WORK Identification – – – – Criminal Missing Person Lost or stolen property Civilian Communication and Microfilm files – Transmission of photos (wire and radio photos) – Investigative report files Evidence – Recording and preserving Crime scenes Vehicular accidents Homicide or murder Robbery cases Fires or arson Object of evidence Evidential traces – Discovering and proving By contrast control By magnification By invisible radiation Action of offenders (Recording) – – – – Surveillance Burglary traps Confessions Re-enactment Court Exhibits – – – – Demonstration enlargement Individual photos Projection slides Motion Pictures Crime Prevention – Security clearance – Prepared training films (Police tactics, investigation techniques) Traffic studies Documentations (riots and mob control, disaster, prison disorders) Public Relation Police Training – – Reproduction and copying – – Photographs Official records B. PHOTOGRAPHY DEFINED It is an art or science which deals with the reproduction of images through the action of light, upon sensitized materials (film or paper) with the aid of a camera and accessories and the chemical processes involved therein. PRINCIPLES OF PHOTOGRAPHY Photograph is both the mechanical and chemical result of photography. To produce a photograph, light is needed aside from sensitized materials (film or paper). Light radiated or reflected by the subject must reach the film while all other lights are exclude by placing the film inside a light tight box (camera). PHOTOGRAPH From the Greek word which means: - photo means light - graph means to draw The effect of light on the film is not visible in the formation of images of objects. To make it visible, we need or required 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 an opaque or very black shade after development. Too little 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, filter used, etc.. HOW DOES THE LIGHT TRAVELS? C. DIFFERENT PHOTOGRAPHIC RAYS X-ray – radiation having a wavelength between .01 to .30 nanometer or millimicrons. They are produced by passing an electric current through a special type of vacuum tube. Ultra-violet rays – radiation having a wavelength from 30 to 400 milli-microns. It is used to photograph fingerprints on multi-colored background, documents that are altered chemically or over writings and detection of secret writings. Visible light rays or White light – rays having a wavelength of 400 to 700 milli-microns. Infra-red rays radiation having a wavelength of 700 to 1000 millimicrons. It is used in taking photographs of obliterated writing, burnt or dirty documents or blackout photography. COLORS IN PHOTOGRAPHY THE PRIMARY COLORS THE SECONDARY COLORS D. TYPES OF LIGHTNING CONDITION Natural (Sunlight) a. Bright- object in open space casts a deep and uniform shadow b. Hazy – object in open space casts a transparent shadow c. Dull – object in open space casts no shadow Artificial – Continuous radiation – incandescent lamps, fluorescent lamps, photoflood lamps, etc. – Short duration – chemical flash (Flash bulb), electronic flash. E. TYPES OF FILM ACCORDING TO SPECTRAL SENSITIVITY Perhaps the most important characteristics of a film is its variation in response to the different wavelength of light source which is called spectral sensitivity. Blue sensitive – sensitive to ultra-violet rays and blue color only. Orthochromatic – sensitive to ultra-violet rays, to blue and green color. It is not sensitive to red color. Panchromatic – sensitive to ultra-violet rays, to blue, green and red color. Infra-red – sensitive to ultra-violet rays, to all the colors, and also infra-red rays. F. EMULSION SPEED The extent to which an emulsion is sensitive to light is referred to its emulsion speed. Emulsion Colors Emulsions are thin, gelatinous, light-sensitive coatings on film that react chemically to capture the color and shadings of a scene. The four layers pictured here show the same image as it would appear on different emulsions in photographic film after the first stage of developing. For black-and-white photographs, only one emulsion is required, because it is the amount of light, not the color, that activates the chemical reaction. Color film requires three layers of emulsions, each of which is sensitive to only one of the primary colors of light: blue, green, or red. As light passes through the layers, each emulsion records areas where its particular color appears in the scene. When developed, the emulsion releases dye that is the complementary color of the light recorded: blue light activates yellow dye, green light is magenta, and red light is cyan (bluish-green). Complementary colors are used because they produce the original color of the scene when the film is processed. Microsoft ® Encarta ® Reference Library 2004. © 1993-2003 Microsoft Corporation. All rights reserved. The two general types of speed ratings are: ASA (American Standards Association) - This is expressed in arithmetical value system. The speeds in numbers are directly proportional to the sensitivity of the material. A film with an arithmetical value of 400 is four times as fast as one with a speed of 100. DIN (Deutche Industri Normen) Rating - This is expressed in logarithmic value system. In this system an increase of 3 degrees double the sensitivity. ISO Rating (combination of ASA and DIN rating) G. CHARACTERISTICS OF PHOTOGRAPHIC PAPER According to chemical contents – chloride papers, bromide papers, chloro-bromide papers. According to contrast #0, #1, #2, #3 According to physical characteristics – weight (single, double) surface (glossy, semi-matte, matte) color (white, cream). H. CAMERA A camera is basically nothing more than a light tight box with a pinhole or a lens, shutter at one end and a holder of sensitized material at the other. While there are various kinds of camera from the simplest construction (Box-type) to the most complicated, all operate on the same principles. The exposure of the sensitized material to light is controlled by the lens and its aperture, and the shutter through its speed in opening and closing of lens to light. The essential parts of a camera are: a light tight box, a lens, a shutter, a holder of sensitized material, and viewfinder. All other accouterment of any camera merely make picture taking easier, faster, and convenient for the operator and are called accessories. Body or Light Tight Box - suggest an enclosure devoid or light. An enclosure, which would prevent light from exposing the sensitized material inside the camera. This does not necessarily mean that the box or enclosure to always light tight at all the times because if it does, then no light could reach the sensitized material during exposure. It means that before and after the extraneous light, which is not necessary to form the final images. Lens – the function of the lens is to focus the light coming from the subject. It is chiefly responsible for the sharpness of the image formed through which light passes during the exposure. Shutter – is used to allow light to enter through the lens and reach the film for a pre-determined interval of time, which light is again blocked off from the film Holder of sensitized material – located at the opposite side of the lens. Its function is to hold firmly the sensitized material in it’s placed during exposure to prevent the formation of a multiple or blurred image of the subject. View-finder – it is a means of determining the field of view of the camera or the extent of the coverage of the lens. I. INHERENT DEFECTS OF LENSES Spherical Aberration – photographic rays passing through the edges of a lens are bent or refracted more sharply than those passing through the central part of the lens, thus they coming to a focus nearer the lens than those of the central rays. Coma – sometimes known as lateral spherical aberration. It concern with rays entering the lens obliquely. Curvature of the filed – when the image formed by a lens comes to a sharper focus on curved surface than on a flat surface. Distortion – outer parts of the image produced by the lens will be magnified either less or more than the center image. – Barrel distortion – diaphragm is placed in front of the lens. – Pincushion distortion – diaphragm is placed behind the lens. Chromatic Aberration – inability of the lens to focus all the colors in the same place. Astigmatism – inability of the lens to focus lines running in different direction like for example a cross. Chromatic difference by magnification – inability of the lens to produce image sizes of objects with different colors. Flares a. optical b. mechanical J. TYPES OF LENSES AS ACCORDING TO THEIR DEGREE OF CORRECTION Achromatic lens – a lens corrected for chromatic aberration. Rapid Rectilinear – lens corrected for distortion. Anastigmat lens – lens corrected for astigmatism. Apochromat lens – lens corrected for astigmatism but with a higher correction of color. K. LENS CHARACTERISTICS Focal length – is the distance measured from the optical center of the lens to the film plane when the lens is set of focused at infinity position. As according to focal length, lenses maybe classified as: – Wide-angle lens – a lens with a focal length of less than the diagonal of its negative material. – Normal lens – a lens with a focal length of approximately equal or more but not more than twice the diagonal of its negative material. – Long or Telephoto lens – a lens with a focal length of more than twice the diagonal of its negative material. Relative aperture – the light gathering power of the lens is expressed in the Fnumber system. It is it is otherwise called the relatives aperture. It is an opening that changes in size to admit more or less light (similar to the iris of an eye). The numbers on the aperture control are called F-stops and referred to as F16, F11, F8, and so on. By increasing or decreasing the Fnumber (F-stops) numerically, it is possible to: – control has the amount of light passing through the lens – control the depth of field – control the degree of sharpness due to the lens defects. The aperture control may look something like this: Here's how it works: – The larger the F-stop number, the smaller the opening. – Each number higher lets in half as much light as one number lower. For example, F5.6 admits twice as much light as F8, while F11 lets in only half as much. The aperture doesn't work alone, however. The shutter speed is responsible for exposure, too. It controls the amount of time light is allowed to reach the film. Depth of field – is the distance measured from the nearest to the farthest object in apparent sharp focus when the lens is set or focused at a particular distance. Hyper focal distance – is the nearest distance at which a lens is focused with a given particular diaphragm opening which will give the maximum depth of field. Focusing – is the setting of the proper distance in order to form a sharp image a lens of a camera except those fixed focused requires focusing. A lens maybe focused by any of the following. - Focusing scale or scale bed – a scale is usually found at the lens barrel indicating pre-settled distance in feet or in meters. To focus the lens of the camera, the distance of the object to be photographed is measured, estimated, or calculated and the pointer or maker on the lens barrel is adjusted to the corresponding number on the scale. Range-finders – is a mechanism that measures the angle of the convergence of light coming from a subject as seen from two apertures. There are two types of rangefinders: - Split-image through the range finder, the image of a straight line in the object appears to be cut into halves and separated from each other when the lens is not in focus. When the images of the lines are aligned, the lens is in focus. - Co-incident image – through the eyepiece, a single image is seen double when the subject is out of focus. Make the image concede and the lens is in focus. . Ground Glass – is focused by directly observing the image formed at the ground glass, screen placed behind the taking lens. If the image formed is blurred, fuzzy, or not clear, the lens is out of focus. Make the image sharp, the lens is in focus. Zone – this is possible in wide angle lenses only. There are only three settings for focusing. One for close distance (approximately 3-6 ft) another for the medium distance (approximately 6-15 ft) and finally for distance objects (approximately 15 infinity). L. Shutter – A contraption or device used to block the path of light passing through the lens and exposing the sensitized material. - is a device that opens and closes at varying speeds to determine the amount of time the light entering the aperture is allowed to reach the film. Shutter speed is measured in fractions of a second. 125 means 1/125 of a second, 60 means 1/60. Typical shutter speeds range from 1 second to 1/1000. A shutter speed setting for a bright, sunny day using an aperture of F11 - might be 1/125 second. A cloudy day might use 1/60 second with the same aperture, exposing the film to light for a longer period of time. The settings for a good exposure are determined by a light meter. (Most 35mm cameras have a built-in light meter that shows you the appropriate settings, or automatically controls them.) Aperture and shutter settings work together. Because the shutter (like the aperture) approximately halves or doubles the light reaching the film with each change in setting, a number of different combinations of settings can result in the same exposure. Aperture F22 F16 F11 Shutter 1/3 0 F8 F5.6 1/6 1/12 1/25 1/50 0 5 0 0 Any of the combinations shown above would result in approximately the same exposure. - Generally there are two types of shutters: Central Shutters – one that is located near the lens (usually between the element of the lens). It is made of metal leaves and its action starts from the center toward the side then closes back to the center. Focal Plane Shutter – is located near the focal place or the sensitized material. It is usually made of cloth curtain. Its action starts on one side and closes on the opposite sides. M. Exposure – is the product of illumination and time. Exposure is computed by any of the following methods. 1. Use of light or exposure meter. The amount of light coming form a source or the amount of light being reflected by the subject is measured by the light meter. Proper adjustment therefore becomes simplified. 2. By taking into consideration exposure factors like; emulsion speed or film sensitivity, lightning condition, kind of subject. Example : When using a film with an ASA rating of 100, for a normal subject, set the shutter speed at 1/25 of a second and adjust the diaphragm opening in accordance with the following lightning conditions. Bright sunlight – f-11 Hazy sunlight – f-8 Dull sunlight – f-5.6 Exposure errors affects: a. detail b. tone reproduction c. contrast Aperture F22 F16 F11 F8 F5.6 Shutter 1/30 1/60 1/125 1/250 1/500 N. CHEMICAL PROCESSING Development – is the process of reduction. Expose silver halides are reduced into metallic silver. There is a separate developer for film (D76) and another for paper (Dektol). The factors that affect developing time are: agitation, temperature, concentration of chemicals and exposure. Stop-Bath – an intermediate bath between the developer and the fixer. It is usually a combination of water plus acetic acid or just plain water. Primarily, its function is to prevent the contamination of two chemical solutions. Fixation – the process of removing unexposed silver halide remaining in the emulsion after the first stage of the development of the latest image. The usual composition of an acid fixing solution are solvent silver halide known as hypo, an anti-staining agent like acetic acid, preservative like sodium sulfite, and a hardening agent like potassium alum. Processing Method – negative-positive method, reversal method Developing Film Developing photographic film requires a series of chemical baths that cause the latent image on the exposed film to become visible as a negative. The process begins with the developer (1), which causes metallic silver to form where the film has been exposed to light, in densities that depend on the amount of exposure. To stop the action of the developer, film goes into a stop bath (2). After a rinse in water, the film goes into a fixer (3) to removes any silver salts not converted to metallic silver. After a short rinse, the film is submerged in fixer remover (4) to clear any remaining fixer from the film. The final bath (5) is a thorough rinse in water. The developed negative is then allowed to dry. Printing Photographs Producing a photographic print from a developed negative also requires a series of chemical baths. The process begins by projecting light from an enlarger through the negative and onto a piece of photographic paper (paper treated with a light-sensitive coating). A developer bath (1) makes the positive image visible on the paper; a stop bath (2) stops the action of the developer so the print won't continue to darken; and a fixer bath (3) and a thorough rinse in water (4) remove any remaining reactive chemicals. The finished print then dries. CHEMICAL COMPOSITION OF DEVELOPER Reducers or developing agents – Elon, Hydroquinone Preservative – sodium sulfite Accelerator – sodium carbonate Restrainer or fog preventer – potassium bromide CHEMICAL COMPOSITION OF A FIXER Dissolving agent – Hypo or sodium thiosulfate Preservative – sodium sulfite Neutralizer – boric acid, acetic acid Hardener – potassium alum FACTORS THAT AFFECTING DEVELOPING TIME Characteristic of negative material Strength and composition of the developer Temperature of the developing solution Agitation or stirring during development O. ENLARGING TECHNIQUES After processing an exposed film into a negative, the next step would be to turn the negative into a positive print or copy. This could be done by either contact printing or projection printing. For contact printing, a contact printer is used while in projection printing an enlarger is needed. FOUR ESSENTIAL PARTS OF AN ENLARGER 1. 2. 3. 4. a a a a base and stand lamp house condenser or diffuser lens ACCESSORIES OF THE ENLARGER 1. a negative holder 2. easel (Paper holder) STEPS IN ENLARGING Preparation of the darkroom, chemicals and the enlarger. Put off white light, switch on red light. Place the negative in the negative holder with the dull side of the negative facing down. Insert the negative holder into the enlarger. Switch on the enlarger’s light. Adjust the easel to the desired size of the photograph. Focus the lens of the enlarger. Focusing is done by first opening the lens diaphragm fully. After the image has been focused, and the density of the negative permits, the lens of the enlarger must be stop down a little bit. Switch off the light of the enlarger. Insert the photographic paper in the easel with the shinny side facing up. Make the exposure. Immerse the exposed photographic paper in the developer. The usual developing time for a normally exposed paper is about 1 to 1½ minutes. Transfer the developed print in the stop bath for about 30 seconds. Place the prints in the acid fixer. The fixing time is about 30 minutes. Wash the prints in running water for about 20 to 30 minutes. Drying Mounting REMEDYING CHEMICAL DEFECTS IN NEGATIVES – Underdeveloped -Intensifier – Overdeveloped – reducer – Stains – Stain remover FREQUENT FAULTS IN PRINTING Blurred exhibits Muddy and mottled exhibits Yellowish exhibits Dark exhibits Light exhibits Harsh exhibits Flat exhibits Fogged exhibits Blemishes on prints Distorted prints P. CRIME SCENE PHOTOGRAPHY PHOTOGRAPHIC PROCEDURES The camera should be mounted on a sturdy tripod whenever to prevent camera movement. The camera should be leveled whenever commensurate with the particular photograph to be taken. Crime scene views include three general classes. – Long views, showing general location and conditions. – Medium views, pinpointing a specific object of evidence or significant segment of the crime scene. – Close-up views, recording position and details. Photographs should be taken progressively as the photographer enters the building or room to avoid disturbing something that might otherwise remain unnoticed, and to maintain continuity. Views should be taken to illustrate the general location of the scene of the crime. A large outdoors scene or a matter involving several buildings may call for any material view. Definitely required is the view of exterior of the building when the crime was committed inside. It is well to include the street number when this is possible. 7. Needed next is the complete photographic coverage of the inferior rooms within a crime area which show the condition in general and relate the overall scene to specific items and places. 8. Bodies of victims should be photographed exactly as found from all angles and especially from overhead when this can be done for identification purposes. - Close-up photographs, one to one, if possible, should be taken all wounds, bruises, discolorations and abrasions-generally with colors. Measuring devices such as rulers, yardstick, and tape measures can be used to show the relative size of and distance between objects or the degree of magnification of an enlargement. There should obscure any important part of the evidence. In photographing a document for example, the ruler a six inches (or 15 centimeter) is placed at the bottom or just below the object will show the relative size of objects in a photographing exhibit. Field notes. -Record the date and time of arrival at the crime scene as well as the time of departure from the scene. -Specifically record the location area, street number, name of building, type of scene. -Write down the names and badge numbers of all investigative officers present during photographing. -Total and record the number of exposures, which necessitates the bad negatives and be saved for the record. -Record specific information on each exposure. This should include the time of taking of each pictures, which can be expressed either using AM or PM or on military type 24 hour scales which 3:00 PM becomes 1500 hours. Additionally: pointed -Direction of camera where it was -General statement of what has been photographed -Exposure to ASA rating -Kind of film -The lighting, whether available, flood lamps, flash lamps, etc. Problems in Fingerprint Photography – – – – – – Black fingerprint on colored background White fingerprint on colored background Fingerprint on multi-colored background Fingerprint on glass Fingerprint on Polished metal Fingerprint on papers PROBLEMS IN QUESTIONED DOCUMENTS PHOTOGRAPHY On handwritings – – – – Sequence of crossed lines Writing over folds Differentiation of inks and pencils Patching On papers – – – – – – – Erasures Watermarks elimination of paper background Faded writing Restoring erased writing Stamped out writing burned papers FILTERS is a homogeneous medium which absorbs and transmits differentially light rays passing through it. A color filter works in such a way that it will transmit its own color and absorbs other colors. By using filters in combination of black and white films, the photographer can control tonal blues to get a technically correct condition or to exaggerate, or suppress the tonal differences for visibility, emphasis, and other effects. With color films, filters are use to change the color quality of the exposing lights to secure proper color balance with film being used. FILTER FACTORS Because filter subtract some of the light passing through the lens, and increase in an exposure time or lens opening is necessary. The number of lines that the normal exposure must be multiplied is called “filter factor”. The filter factor value depends on film type and light source in addition to the absorption of the filter. TYPES OF FILTERS IN BLACK AND WHITE PHOTOGRAPHY – – – – – Correction filter- used to change the response of the film so that all colors are recorded at approximately the relative brightness value seen by the eye. Contrast filter- used to change the relative brightness values so that two colors which would otherwise be recorded as nearly the same will have decidedly different brightness in the picture. Haze filter- used to illuminate or reduce the effect of serial haze. Neutrally density filter- used for reducing the amount of light transmitted without changing the color values. Polarizing filter- used to reduce or illuminate reflection on highly reflective surfaces. YOUR ACHIEVEMENT IS OUR ACCOMPLISHMENT!! SO….. READ MORE…. LEARN MORE…. AND PASS THE BOARD!!! THAT’S ALL FOLKS!!!