DIN system
noun
¦dēˌīˈen-
: a system for determining the speed of photographic materials in terms of the logarithm of the reciprocal of the exposure required to obtain a density of 0.1 above fog density
Word History
Etymology
DIN from German, abbreviation of Deutsche Industrie-Normen (literally, "German industry standards"), standards for industrial products established by the Deutscher Normenausschuss, a German organization for the establishment and registration of standards in all branches of industry