>> He gave us an equation and we worked through an example with a 50mm
>> f/2 lens. It turns out that the resolution limit DUE TO DIFFRACTION
>> is on the order of about 500 line pairs per millimeter.
> Hopefully he pointed out that you have to shoot at maximum aperture to >
> THEORETICALLY get the maximum resolution and minimum loss due to diffraction.
> > The article in Photo Techniques on the Leica 50mm f/1.0 Noctilux shows that
> > as you stop down any lens you progressively reduce the potential
> resolution. > Thus, f/22 is often an inferior aperture on our most widely
> used Zuikos.
Actually, it's true for virtually _every_ lens ever made (unless it's a
really bad lens in which the aberrations mask the diffraction loss).
I've been reading test reports for almost 30 years, and I don't remember
a lens that didn't show at least a little degradation starting at f/16
or f/22.
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