Quote Originally Posted by ntenny View Post
I suppose the resolution of the film matters as well, since the meaningful diffraction limit is measured in lp/mm---your film has to be capable of resolving the diffraction before it matters.

f/8-f/11 sounds too low (wide) to me. If 1500/f is a good rule of thumb, that would imply that the lens has a "native" resolving power of around 150 lpmm...? But maybe I'm misunderstanding something.

You are. The diffraction limit can be approximated by dividing the f stop into 1500, as it depends upon the aperture you're working at. F:2 = 750. f:4 = 375. Diffraction limit means that the lens is well enough corrected that diffraction, not aberrations, are the limiting factor for resolution. It does not mean every f:2 lens resolves 750 lp/mm