Upload & Sell: On
I've resolved the issue. In all my EV8 lensalign shots where AF tune was best at -1, I had an LED (4750K) or CFL tungsten (2750K) bulb at close proximity to the lensalign target, which creates a very high contrast target with high CA. For reasons which are not exactly clear to me yet, that high-contrast high-CA target produces a much different ideal AF tune value than all other AF scenarios I've since tried, including the same lensalign target but without the high-contrast lighting, plus all the real-world subjects I tried today, including some high-contrast targets in daylight sun. In all those other scenarios a +9 AF tune was best. And with that value, wow, the 5DM3 incredibly consistent with my 50mm wide open @ f/1.4, at all focus distances including mid-range distances (20 feet to 1/2 infinity), a feat no other PDAF camera I've ever had has achieved, including the 5D, 5DM2, D3, D3s, and D800.