Pet peeve, by why do people persist in using wide aperture closeups to test resolution? If almost everything in the frame is out of focus, then duh, you're not going to notice much difference between 'high resolution' and 'very high resolution'.
past f8 on full frame (and wider on smaller frames) you run into diffraction, so you actually do get more detail with a slightly wider aperture. i only glanced at the links but it seems about right.
Sure, but why not shoot a subject at infinity? (I said "wide aperture closeups".) It's hard to even know which tiny part of the face is actually in perfect focus. And at the resolutions tested, you will need perfect focus to see any difference.
