DIRECT POSITIVE A positive image obtained directly from another positive image without the use of a negative.

DODGING A printing technique in which certain areas being exposed are temporarily shielded, thereby producing a different exposure than that used for the rest of the print.

DROPOUT A loss of part of the video signal that appears as white glitches. Caused by dirty VTR heads or poor quality videotape.

DRY MOUNTING A method for mounting photographs or artwork on a support by means of a thermosetting laminate that is heated to effect a bond. (PIA)

DRYING MARK Spots or streaks on negatives and prints differing in density from the surrounding area, produced by uneven drying of the film during processing.

DUB Duplication of an electronic recording, either tape to tape, record to tape, or vise versa. Dub is always one generation away from the original recording.

EKTACHROME A trademark of Eastman Kodak Company for a multilayer reversal color film in which couplers are incorporated in the emulsion layers that form dyes in the emulsion during processing.

EKTACOLOR A trademark of Eastman Kodak Company for a multilayer color negative film in which dye couplers are incorporated in the emulsion layers which upon development produce dye images complimentary to the object colors. Unused couplers remaining in the emulsion after development provide automatic masking for correction.

ELECTROMAGNETIC SPECTRUM The entire range of wavelengths, extending from the shortest to the longest or conversely, that can be generated physically. This range of electromagnetic wavelengths extends almost from zero to infinity and includes the visible portion of the spectrum known as light.

EMULSION (SILVER HALIDE) A suspension of light-sensitive silver salt, especially silver chloride or silver bromide, in a colloidal medium, usually gelatin, used for coating photographic film, plates, or papers.

EMULSION SIDE That side of a (single coated) photographic film on which the emulsion has been coated

EMULSION SPEED A comparative measure for a given emulsion of exposure to light required to produce a correctly exposed image.

ENLARGEMENT A print made from a smaller negative through a projection process.

ENLARGER A photographic projection printer. (PIA)

EXHAUSTION The state of depletion reached by a processing solution due to age or use that makes it incapable of producing satisfactory results. (PIA)

EXPIRATION DATE A date placed on sensitized photographic material packaged by the manufacturers to limit the period during which it is warranted to produce normal results.

EXPLODED VIEW A photograph showing the correct sequence and relationship of the various parts of an assembly. Also called an exploded photograph.

EXPOSURE (l) The act of exposing a light-sensitive material to a light source. (2) A section of a film for an individual exposure, as a roll containing six exposures. (3) The time during which a sensitive surface is exposed, as an exposure of 2 seconds. (4) The product of light intensity and the time during which it acts on a film, plate, or paper.

EXPOSURE INDEX An exposure index is the rating of a film for use in connection with exposure tables, exposure computers, and exposure meters.

EXTENSION TUBE A device used to increase the lens-to-film distance for extreme closeup photography.

FAHRENHEIT A thermometer scale, on which, under standard atmospheric pressure, the freezing point of water is 32 degrees, and the boiling point of water is 212 degrees; usually indicated as 32F and 212F. Fahrenheit temperatures may be converted to Centigrade temperatures with the following formula:

C = 5/9 (F - 32)

when C = Centigrade temperature and F = Fahrenheit temperature. (PIA)

FAST Having a high-photographic speed. The term may be applied to a photographic process as a whole, or it may refer to any element in such a

AI-6 process, such as the optical system, the emulsion, or a developer.

FAST FILM Photographic material of relatively high sensitivity to light, having a high-exposure index. (PIA)

FIELD Scanning lines in one half of one video or television frame. There are two fields (one odd, one even) in a frame. One field equals 262.5 scanning lines that create a total of 525 standard television lines or one frame. Also known as the NTSC signal (U.S. T.V. system).

FILM, COLORBLIND Film which is sensitive only to light of very short wavelengths (ultraviolet, violet, and blue). (NMA)

FILM, PHOTOGRAPHIC, INFRARED Film coated with an emulsion especially sensitive to infrared light.

FILM, PHOTOGRAPHIC, ORTHOCHROMATIC (ORTHO) A black-and-white film coated with an emulsion that is sensitive to ultraviolet, violet, blue, and green radiation. Not being sensitive to red, red objects photographed with orthochromatic films are rendered dark on the print.

FILM, PHOTOGRAPHIC, PANCHROMATIC (PAN) A black-and-white film coated with an emulsion that is sensitive to ultraviolet, violet, blue, green, and red radiation. The special sensitivity of panchromatic films approach that of the human eye.

FILM, PHOTOGRAPHIC, REVERSAL A film which after exposure is processed to produce a positive image instead of the customary negative image. Reversal films may be black and white or color.

FILTER Photographic. A layer of glass, gelatin, or other material used to modify the transmitted light selectively.

FILTER, NEUTRAL DENSITY One not selective for a certain portion of the spectrum but absorbing all colors equally, thus reducing the intensity of light without changing its chromaticity.

FILTER FACTOR The number of times exposure must be increased to compensate for light absorbed by a filter.

FIXED FOCUS The term applied to optical instruments and photographic equipment that are not provided with a means for focusing.

FIXER A solution used to remove undeveloped silver halides from photosensitized emulsions. The fixer usually contains sodium or ammonium thiosulfate, a hardening agent, and an acid or acid salt.

FIXING AGENT A photographic chemical that dissolves the silver halides not used for producing an image to preserve the photograph from further photographic effect upon subsequent exposure to light. Common fixing agents are sodium thiosulfate and ammonium thiosulfate.

FLARE A defect of optical systems in which scattered light resulting from reflections at optical surfaces, the walls of the camera, or imperfections in the optical parts, reaches the image plane and produces an overall fog or flare spot that damages the photographic quality of the resulting record.

FLASH, ELECTRONIC A high-voltage light source for photographic illumination, producing a momentary flash of light of high intensity in an atmosphere of gas enclosed in a tube that can be used repeatedly. (PIA)

FLAT An image is said to be flat if its contrast is too low. Flatness is a defect that does not necessarily affect the entire density scale of a reproduction to the same degree. Thus a picture may be flat in the highlight areas or flat in the shadow regions, or both.

FLOATING LID A lid designed to float on the top of a photographic processing solution to reduce aerial oxidation.

FLOODLIGHT A photographic light used to produce even lighting on large subjects. A floodlight spreads light evenly over a wide angle, as distinguished from a spotlight that concentrates light in a beam.

FLUID OUNCE A unit of capacity in the Liquid Measure System equal to 1.8 cubic inches; it is equal to 29.57 milliliters.

FOCAL PLANE The surface (plane) on which an axial image transmitted by a lens is brought to sharpest focus; the surface occupied by the light-sensitive film or plate in the camera.

FOCAL POINT The point at which converging rays of light from a lens meet.

FOCUS (l) The point at which rays of light passing through different parts of a lens converge to form a sharp image of the original. (2) (Verb) To adjust the position of either the lens or focusing screen in a camera or projector to secure the sharpest possible image of the object.