AF - that center point is pretty damn accurate and I couldn't find many lighting situations where the 6d said no, can't do it (without a flash attached!)
This thread is getting a bit long and random, but I have a new & real question here. Today I had a test with the 6d (again :-)) with the 70-300L and while I still feel the 6d is overpriced (Germany: 1700€) for various reasons I ran into a real issue:
How do you manage to get something in focus in the corners?
Obviously it's me because people have been shooting with the 5d2 and thin dof lenses for years, but I cannot seem to manage - on my 60d the outer af points are further from the center, but on the 6d once I focus and recompose the focus is off most of the time. Are there any tutorials how to do it? How do you do it - trial and error, then take the in focus shots?
Simple ... use live view and focus manually if necessary
Focus and recompose is a tough baby at wide open apertures. I don't use the focus and recompose method at anything wider than f/4 - However, there are people who do it with success but the chance of error is usually high.
It may be worth pointing out that in low light, all focus points save the center point don't lock on focus at all and focus and recompose is the only option left