Eerily enough, that was what I was about to suggest to you, but I considered it too rude to do so to a fellow photographer.
Considering that you brought it up that way, however, I don't, anymore.
Since you don't appear to know much about diffraction and why it isn't a significant effect of a particular lens design, as much as it as to do with the aperture, I not-so-humbly suggest that you re-read the theory, and reconsider that you might be confusing "diffraction" with another technical term related to lens performance.
You pretend to be polite whilst being rude. I have no idea what point you are trying to make if any.
Ray stated that lens resolution is pretty much constant throughout the aperture range for most lenses apart from old designs. I disagree with that statement. He has now changed his mind.
"Since you don't appear to know much about diffraction and why it isn't a significant effect of a particular lens design, as much as it as to do with the aperture, I not-so-humbly "
Quite why you make such an obvious statement is beyond me. It is the very reason why I disagree with Ray's original statement.
In most camera lenses the resolution is nowhere near the diffraction limit except when stopped well down other aberrations being dominant at wider apertures. Some Schmidt cameras are fast - e.g. F1.0 - and much closer to being diffraction limited. I am sure you can find information on this from Google. Some of it might be accurate.
You might wish to read up on concepts such as the Dawes Limit and Rayleigh limit, which are measures of the theoretical maximum resolution of a telescope, but have relevance to camera lenses when stopped well down.