Definition of Terms
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Definition of Terms Forensic photography sometimes referred to as forensic imaging or crime scene photography is the art of producing an accurate reproduction of a crime scene or an accident scene using photography for the benefit of a court or to aid in an investigation. It is part of the process of evidence collecting. It provides investigators with photos of victims, places and items involved in the crime. Pictures of accidents show broken machinery, or a car crash, and so on. Crime scene photography is a branch of the field of photography which is focused on taking accurate photographs of crime scenes and criminal evidence, so that these photographs can be used in the investigation of crimes and in the prosecution of criminal activity. ACETIC ACID – – A relatively mild acid used, in highly diluted form, as the rinse bath (shortstop) which follows the developer in the normal film and paper developing processes. The acid in vinegar. ADAPTER RINGS – – Narrow metal rings, threaded on the outside to fit most popular lens, and threaded on the inside to accept accessories of other than normal lens diameter. Step-up rings adapt a lens for use with larger-than-normal accessories; step-down rings permit the use of slightly smaller accessories than the lens will normally accept. ADJECTABLE CAMERA – – A camera with manually adjustable distance settings, lens opening, and/or shutter speeds. AGITATION – – The process of stirring, swirling, or otherwise causing a liquid to move freely over the surface of film or paper during processing. Agitation helps to speed and achieve even development and prevent spotting or staining. ANGLE OF VIEW – – The portion of scene that is covered through a camera lens. The width of this wedge-shaped portion is determined by the focal length of the lens. A wide-angle (short-focal-length) lens includes more of the scene – – a wider angle of view – – than does a normal (normal-focal-length) or telephoto (long-focal-length) lens. APERTURE – – The opening in a diaphragm of a lens through which light passes, expressed as a fraction of the focal length. The f/number. APERTURE PRIORITY – – A camera feature that lets you select the desired aperture, and the camera sets the shutter speed for proper exposure. When you change the aperture or when the light level changes, the shutter speed changes accordingly. AUTOFOCUS – – The camera focuses automatically on the subject in the center of the viewfinder when you press the shutter release. AUTOMATIC EXPOSURE (AE) – – A system whereby the camera selects and sets an exposure based on prevailing conditions without intervention by the photographer. ARTIFICIAL LIGHT – – Any light other than produced by the nature (sun, moon, stars, phosphorescence, etc). Electric lights are the principal artificial light source in photography. AVAILABLE LIGHT – – The light condition which the photographer finds existing at the subject position. The term usually implies an indoor or nighttime light condition of low intensity requiring fast film, large lens aperture, and slow shutter speed. AVAILABLE LIGHT PHOTOGRAPH – – Photography without supplementary illumination even under poor lighting conditions. BB – – (BULB) – – A marked setting on most shutters which permits the shutter to be held open for an indefinite period by continued pressure on the shutter release. BACK – – That portion of a camera which contains the film; specifically, the complete assembly attached to the rear standard view camera (and usually removable) which includes the focusing screen, and which accepts the film holders. BACK LIGHT – – Illumination from a source beyond the subject, as seen from the camera position, which tends to silhouette the subject, also called Back Lighting. BASE – – The transparent sheet material, usually acetate or polyester, upon which film emulsion is coated. BASEBOARD – – The large, flat board, usually plywood, to which the enlarger column is attached, and on which the enlarger easel is normally placed. BASE FOG – – Any uniform fog produced when an unexposed emulsion is developed. BASE-PLUS-FOG-DENSITY – – The density of an unexposed area of a developed film (negative or positive). BELLOWS – – The center section of a view camera which connects the front and back standards. The bellows is usually made of leather, cloth, or plastic, is accordion-pleated for flexibility and is, of course, light tight. BELLOWS EXTENSION – – A term often used to refer either to the total bellows length or to the additional extension of the bellows (beyond that required for infinity focus) necessary for focusing at close subject distances. BELLOWS EXTENSION FACTOR – – A number (multiplier) indicating the exposure increase required for correct exposure. BETWEEN-THE-LENS SHUTTER – – A shutter designed to operate in a space between the elements of the lens. BLIND – – An emulsion not sensitive to certain colors; color blind. BLUE-SENSITIVE – – The sensitivity of an ordinary silver emulsion; red and green blind. BOUNCE FLASH – – Directing light from a flash gun toward a ceiling, wall or other large reflecting surface to obtain the contrast softening effect of a diffused light source spread over a larger area of the subject. BOUNCE LIGHT – – Light reflected onto the subject from surrounding surfaces rather than directly on the subject. BRACKET – – To make a number of exposures (some greater and some less than one considered to be normal) in addition to the "normal" one, with the intent of getting one near-perfect exposure. BURNING-IN -- The process of allowing some relatively small image area to receive more than the normal exposure by shielding most of the printing paper surface from the light. BURNED-OUT – – Describes an area of the print image in which highlight detail has not been recorded, usually because of severe overexposure of the negative. CABLE RELEASE – – A flexible outer casing containing a stiff wire which can be attached to the shutter release on a camera. Depressing the plunger at the end of the wire release the shutter while minimizing risk of camera movement during exposure. CAMERA MOVEMENTS – – Adjustments typically provided on technical and view camera to (1) enable the optical axis of the lens to be displaced relative to the center of the image while keeping the axis perpendicular to the image plane. (2) Position the lens plane and image plane at an angle to each other (swings and tilts). These adjustments may be provided as a swing front lens panel or a hinged camera back (swing back) or both. They are used for control of perspective and sharpness distribution in the image plane. CHEMICAL FOG – – Fog on negatives or prints appearing, during development, in the unexposed areas. CLEAR – – The appearance of a negative after the fixing bath has removed all visible traces of undeveloped silver halide. CLEARING TIME – – The length of time required to clear a negative. It depends on the strength, temperature, and agitation of the fixing bath and the kind of emulsion being used. CLOSE-UP – – Photograph made of an object to show greater detail. A photograph made with a reproduction ratio greater than 1:10. CLOSE-UP LENS – – A positive supplementary lens which, when placed over a camera lens, shortens its focal length and thereby permits closer-than- normal focusing. CLOSE-UP PHOTOGRAPHY – The techniques and practice of using supplementary lenses, extension tubes, bellows units, etc. to take pictures at closer ranges than the normal focusing adjustment of an ordinary hand-camera will allow. Refers to image magnification ratios of up to perhaps, 2x, and therefore overlaps "Photomacrography". COLOR BLANCE – The ability of a film to reproduce the colors of a scene. Color films are balanced in manufacture for exposure to light of a certain color quality; daylight, tungsten, etc. Color balance also refers to the reproduction of colors in color prints, which can be altered during the printing process. COLORBLIND – Descriptive of the partial or total inability to recognize or distinguish chromatic emulsion is sensitive only to blue, violet, and ultraviolet light. COLOR HEAD – An enlarger light source containing adjustable dichroic filters which can be set to provide light of any color for color printing. COLOR TEMPERATURE – A numerical rating given to the color qualities of a light source. Expressed in degrees Kelvin. The lower the color temperature, the greater the ratio of yellow/red light. Daylight is considered to be 5000 – 5500 degrees Kelvin. COMPEMEMTARY COLORS – Any two colors in the subtractive system which, when mixed in the proper proportion, produce black or dark neutral gray. In the additive system, any two colors whose mixture results in white light. CONCAVE – Hollowed out. The side of spherical surface seen from the center of the sphere. CONDENSER ENLARGER – An enlarger with sharp, undiffused light that produces high contrast and high definition in a print. Scratches and blemishes in the negative are emphasized. CONTACT PAPER – Relatively slow development paper for making positives by contact printing. CONTACT PRINTING – A method of printing in which the negative is placed in contact with the printing paper, emulsion to emulsion, and held in that position in a printing frame. The exposure is made by exposing the frame to raw light so that the paper emulsion is exposed by light passing through the negative densities. CONTINUOUS TONE – Describes an image containing a gradation of grays as well as black and white extremes. CONTRAST – The difference in tones from the lightest to the darkest areas of negatives and positives. CONTRAST GRADE – A number or descriptive term assigned to a particular printing emulsion which identifies its contrast characteristic. In the range from zero through five, a normal contrast paper is usually considered to be two, with the lower numbers indicating a tendency toward lower contrast. Printing filters for use with variable contrast papers are numbered similarly. In some cases low contrast is indicated by the term "soft" while high contrast paper are labeled "hard". CONTRASTY – higher than-normal contrast.