ASA (film speed)
ASA · Analoog
The older American film speed rating system, functionally identical to ISO.
ASA stands for American Standards Association. In 1987 ASA was merged with the German DIN standard to create the ISO standard we use today. ASA 100 = ISO 100. You still see ASA on older films and cameras. DIN expressed sensitivity on a logarithmic scale (21° DIN = ASA/ISO 100).