ASA
From The Glossary of Digital Photography
(1) An abbreviation for the American Standards Association. (2) A numerical rating of the sensitivity of a film or a digital sensor to light. The higher the number, the more sensitive the film or sensor. Typical ranges of ASA are from 25 to about 1600, although both higher and lower values are found occasionally. ASA is equivalent to exposure index (EI) and has been replaced by ISO. The numbers are the same in either case. See also E.I.; ISO
