« on: April 24, 2014, 08:32:31 AM »
A tip for you on focusing on 'naked' horses - I am presuming you are shooting wild ones without any head collars or tack on - try using Servo AF with the centre points expanded, and unless very close have all AF points activated. I know this sounds contrary to 'single shot AF' and centre point being more accurate, but I have found that when trying to focus an an animal with very flat fur such as a horse, the aformentioned method is much more successful with the 5DII and 6D.
Alas, the 6d has no af pt expansion, so it's "center" or "all" or "single outer" (non-cross). The problem with outer pts has been described in length, I hope the rocket blower did the trick and there's at least some improvement. "Center" results in a big loss of resolution since I have to crop a lot.
Least and least "all" is extremely unreliable with my 70-300L, the 6d simply cannot decide where to af and keeps shunting around the place once 1-2 outer pts are not on the object. I often feel a real pity for my 6d baby, it's not the camera's fault Canon did such a botch job on the fw and the poor thing has to struggle like this. If I manage to have all pts on the object, the 6d in my experience still doesn't focus on the front, but somewhere else in a totally unpredictable manner - though I didn't try all af options with "all".