Which lens is sharper with TC-20E III: 70-200mm f/2.8 VRII or 70-200mm f/4 on D800/E

Mack wrote:

The f/2.8 lens may give you a better auto-focus lock on than the slower f/4 lens with a 2-stop converter. Once you get up to around f/5.6-f/8 you are questioning the sensors in some cameras and some (less expensive models) may be worse AF offenders than others too. Some may hunt a bit at the slower aperture too and might or might not hit the sweet spot either.

Mack