I have a 4X5 which I thought that I might tinker with. I purchased some Vericolor 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.

-- Doug McKeever (mckeeved@worldnet.att.net), December 12, 1997

Answers

For all practical purposes, they're the same thing.

Once upon a time, film speeds in the U.S. were denominated using the ASA (American Standards Association) system, and in Europe using the DIN system, which originated in Germany. Some years ago, the ISO (International Standards Organization) 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, and the second was the corresponding DIN number. In practice, nobody even uses the second (DIN) number, so what appears on the film package as the ISO speed is exactly what we used to call an ASA speed.

-- Rob Rothman (rrothman@riag.com), December 12, 1997.