From looking at the H&D curves of fast vs. slow films it would seem that with equal amounts of overdevelopment contributing equal amounts of film density, there would be no significant difference between the fast and slow films with regard to overall contrast. Is this correct??

-- r (ricardospanks1@yahoo.com), July 12, 2001

Answers

It's sorta true. If you develop films to the same C.I., gamma, or slope (all a bit different definitions), then the overall contrast will be the same. IMHO, the appearance of the prints will be quite different, not only with regards to grain, but contrast of details (microcontrast?). Another interesting thing is when people talk about tonal range. Most films seem able to produce prints that go from black to white, so I'm not sure the phrase is meaningful. What does matter is the shape of the curve and where good separation occurs. BTW, you refer to "overdevelopment"- over or under, the curves are the curves.

-- Conrad Hoffman (choffman@rpa.net), July 12, 2001.

In general, slower speed films are inherently more contrasty and have higher resolution than higher speed films. It is no coincidence that Kodak Tech Pan film is just about the highest contrast and slowest film on the market. Slower speed films often have less development and higher dilutions recommended for them to make the contrast curves look similar to higher speed films.

-- Michael Feldman (mfeldman@qwest.net), July 12, 2001.