5D Mark III -- Autofocus at f/8! Sort of...
Got my 5DM3 today and have been running it through its paces. Just for kicks, I threw on a Tamron non-reporting 1.4x TC on my 600mm with another 1.4X giving me a focal length of 1176mm @ f/5.6 (at least that's what the 5DM3 thinks. It's actually f/8, but since the non-reporting teleconverter isn't seen by the 5DM3, it thinks it's f/5.6) And???
It autofocuses w/o hunting like crazy. It's a tad slower and jitters on occasion, but it's definitely useable. I have yet to try it on BIF, but I'm quite certain it should work reasonably well.
Besides, the 600mm @ /f.8, I tried the non-reporting TC 1.4x on the Canon 400mm f/5.6 and the Canon 100-400 f/5.6. Both are useable!
Here's a sample I took at the peanut feeder this afternoon under dark and gloomy conditions (Canon 600mm + 1.4x + 1.4x, Canon 5D Mark III, ISO 1600, 1/640 sec):
http://iwishicouldfly.com/iwishicoul...dm3_1176mm.jpg
The 5DM3 autofocus is excellent!
Alan
