I’m not debating the effects of defraction, all I’m saying each lens is different (canon 24-70 2.8 II loses IQ as of f6.3, the 85 1.2 II as of f13, 16-35 2.8 III as of f16) I own each of these lenses plus others on 5D4s so I know a thing or two abt photography. The point I made whatever formula...