Apologies for what i am sure will prove to be a naive question but: When films are described as having effective working speeds or true speeds with certain developers, does this mean that they should be rated as such at the time of exposure?

If this is the case, will the resultant negative have the same characteristics as if exposed at manufacturers recommended ISO and dev. time and temperature?

Many thanks in advance Andrew

-- Andrew Buckley (da_buckley@yahoo.com), March 16, 2001

Answers

Andrew,

"Effective speed" is the film speed setting that gives you the best quality results. With b&w film, this is almost invariably slower (more exposure) than the manufacturer recommends, whatever developer you use. Most often, following the manufacturer's recommendations delivers more contrast and less shadow detail than most experienced photographers would like to have, so after doing personal tests, most end up exposing more--much more with some films--and often developing a bit less.

-- Carl Weese (cweese@earthlink.net), March 16, 2001.