APEX system

The APEX system (English Additive System of Photographic Exposure to German: Additives system to photography exposure) is the prefix in the context of standards - PH2.5 ASA 1960, ASA PH2.12 -1961 and ANSI - 1971 PH3.49 mathematical method to calculate exposure settings in the photograph on the basis of logarithmic underlyings. The goal is to calculate the exposure parameters on the basis of simple addition equations.

See also: light value, film speed, aperture (optics), aperture range (optics), exposure time