Quote Originally Posted by Robert
Quote Originally Posted by Ed Sukach

Hmm... Wondering about this. Do you have any references re: f/stops and resolution?
Diffraction limits?
http://medfmt.8k.com/mf/diffraction.html
also this from the Large format lens testing page.
http://www.hevanet.com/cperez/results.html
Scroll down to the discussion near the bottom.
Both web siites are excellent. Thanks for posting them.

I think that it should be noted that, in theory, the *least* diffraction will occur at the largest possible aperture; but it should be noted that that is only one factor affecting the performance of an an optical system.

Be *very* careful about defintitions here - do not confuse "diffraction limits" with something limiting the entire lens performance - "`Diffraction limited at...' indicates that aperture where lens performance will not *improve* by additional `stopping down'". The lens performance could be extremely high to start with ... so any "improvement" would be very difficult to achieve.

The web sites are in FAQ format - and a diligent study of the questions and answers will provide a good education in just what happens when we talk about the phenomenon we call diffraction.

Lens resolution is not *only* affected by diffraction - there are many, many other optical characteristics involved.