Mark, perceived sharpness seems to have more to do with graininess and edge effects. The smooth edges thing (traditional acutance) doesn't really hold water when you look at what is happening at the microscopic level. It also depends heavily on the film. For example when Altman and Henn did their famous study of solvent effects, guess what - with Panatomic-X, D-25 (an extra fine grain, highly solvent formula) produced the same acutance as D-76 1:1 but with significantly lower graininess. The results were the opposite with Tri-X. Richard Henry's tests were similarly illuminating in revealing that generalizations are impossible. One constant appears to be that you pay a substantially higher price in graininess to get a modest increase in acutance. You might want to check out my thread in the exposure forum.
Originally Posted by markbarendt