View Full Version : ASA or ISO what is the difference

Doug McKeever
12-Dec-1997, 01:53
I have a 4X5 which I thought that I might tinker with. I purchased some Vericol or III (not sure that was the best choice). Since I am used to working in 35mm land, I looked for ASA speed to set my meter, but there isn't one. Instead the film has an ISO code. Can you tell me what to do.

Rob "John Henry" Rothman
12-Dec-1997, 10:34
For all practical purposes, they're the same thing.

Once upon a time, film speeds in the U.S. were denominated using the ASA (Americ an Standards Association) system, and in Europe using the DIN system, which orig inated in Germany. Some years ago, the ISO (International Standards Organizatio n) decided to go into the film speed business. To avoid offending anybody, they adopted a system which contained two numbers. The first was the ASA number, an d the second was the corresponding DIN number. In practice, nobody even uses th e second (DIN) number, so what appears on the film package as the ISO speed is e xactly what we used to call an ASA speed.