I was working with a student on diffraction limits and telescopes yesterday
and thought of a problem I had never considered before. Usually, the
diameter of the 'scope is used in determining the 1.22(lambda)/D limit.
But the light must also pass through the eyepiece lens, which is much
smaller. This should also have a limiting resolution; it seems that,
depending on the location and size of the image, this limit could be more
demanding than that for the 'scope body.
Is this ever a problem, or is it designed away by telescope manufacturers?