Someone please explain this f/8 brouhaha to me: my 5D3 + Kenko 1.4x tele-extender + 400 & 70-300 auto-focus (at f/8, pre-firmware update) all day long. I just downloaded the firmware update and will install it later today, but I've been auto-focusing just fine at f/8 for some time. Am I missing something?
The Kenko locks up the 5DIII when used with the latest generation telephotos, and you have to remove the battery to restart.
5D IV, 5DS R, 7D II, EOS-M, Powershot G3 X, 400mm DO II, 300/2.8 II, 1.4xTC III, 2xTC III, EF 1.8 STM, EF 70-200/4 IS, EF 24-105, 15-85, 100-400 II, Sigma 10-20, Sigma 150-600mm C, EOS-M 18-55, f/2 22, 11-22