logarithmic speed

Definition: System for denoting film speeds in which equally-spaced steps represent twice the speed or sensitivity. * E.g. in the DIN system, a rise of 3º -- e.g. from 18º to 21º -- represents twice the sensitivity i.e. for a given scene luminance, half the exposure is needed for the same density.

Related Terms: DIN

Previous Term: load  Next Term: longitudinal chromatic aberration

Type a photography term below to find its definition: