Max resolution film size for large format.

[DREW WILEY]

There are photographers who deliberately used diffraction esthetically, for a softer-edged feel. For example, Meyerowitz routinely stopped down to f/90 in many of his shots. The effect was evident not only in 30X40 enlargements, but even subtly in 8x10 contact prints. His lens choices included a 10 inch Commercial Ektar and later a 250/6.7 Fuji W, I believe, which are both very sharp in normal usage - so this had nothing to do with a "soft focus lens" look; it was rather about nuance.

We should all feel free to make up our own rules, based on our own objectives and expectation. Perceived sharpness or deliberate modification thereof is just another tool in a potentially very large toolbox.

 

[Dan Fromm]

Back then lenses were uncoated, so you needed to stop down more than today.

Stuff and nonsense.

 

[Harry Callahan]

Uh-huh.