Entertainment / Photography Glossary

A-PEN: Annealed polyethylene naphthalate. A polyester material used as the base on advanced photo system film.

Abbe Number: Denotes the degree of refraction of light of different wavelengths to different extents, given by a transparent material, such as glass. The lower the abbe number, the greater the dispersion . . . View Full Definition

Aberration: The inability of a lens to produce a perfect, sharp image, especially towards the edge of the lens field. These faults can be reduced by compound lens constructions, and the use of small apertures.

Abrasion Marks: Marks on the emulsion surface of a film, caused by scratching. It can be due to traces of dirt trapped between layers of film as it is wound on the spool, or to grit on the pressure plate.

Absolute Released Images: Any images for which signed model or property releases are on file and immediately available.

Absolute Temperature: The temperature at which most molecular movement ceases. It is often referred to as absolute zero (-273° c).

Absorption: The process by which light falling on a surface is partially absorbed by the surface.

Abstract: Subjective, non-realistic image. An abstraction photograph generally contains a design of patterns or shapes where the identity of a subject is not evident.

Accelerator: Chemical added to a developing solution to speed up the slow working action of the reducing agents in the solution.

Acceptable Circle Of Confusion: The size of the largest circle which the eye cannot distinguish from a dot. In 35mm format cameras, a 0.03mm diameter circle of confusion is considered acceptable. It is used to calculate de . . . View Full Definition

Acceptance Angle: See angle of view.

Accessory Shoe: Metal or plastic fitting on the top of the camera which supports accessories such as viewfinder, rangefinder, or flash gun.

Acetate Base: Non-inflammable base support for film emulsions which replaced the highly inflammable cellulose nitrate base.

Acetic Acid: Chemical used for stop baths and to acidify acid fixing solution.

Acetone: Solvent chemical used in certain processing solutions that contain materials not normally soluble in water.

Achromatic: Lens system that has been corrected for chromatic aberration.

Acid: Chemical substance with a ph value below 7.

Acid Fixing Solutions: Solutions which contain an acid to neutralize any carry-over of alkaline developer on the negative or print.

Acid Hardener: Substance used in acid fixer to help harden the gelatin of the emulsion.

Acid Rinse: Weak acid solution used after development and before fixation. By neutralizing alkaline developer left on the photographic material it arrests development.

Actinic: The ability of light to cause a chemical or physical change in a substance.

Actinometer: Early type of exposure calculator.

Acuity: Subjective term for the visual sharpness of an image.

Acutance: Objective measurement of image sharpness.

Adapter Ring: Circular mount, available in several sizes, enabling accessories such as filters to be used with lenses of different diameters.

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