Quote Originally Posted by E. von Hoegh View Post
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
No, I think I'm not misunderstanding something, then. If the Xenar is diffraction-limited at f/8-f/11, and 1500/f is a decent rule of thumb, then that means that the lens resolves circa 150 lpmm, right? Which sounds kind of high, certainly much finer than most films could resolve.

-NT