Film speed
A roll of 400 speed Kodak 35mm film.
Main article: Film speed
Film speed describes a film's threshold sensitivity to light. The international standard for rating film speed is the ISO scale, which combines both the ASA speed and the
DIN speed in the format ASA/DIN. Using ISO convention film with an ASA speed of 400 would be labeled 400/27°. A fourth naming standard is GOST, developed by the Russian standards authority. See the film speed article for a table of conversions between ASA, DIN, and GOST film speeds.
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