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.