Originally Posted by The1
I don't find AI servo the most usefull focusing mode, so may not be the best indicator depending on camera body.
I've taken lots of pictures where i was focusing on an animals head and gotten it's tail in focus with AI servo... it's just too sow to keep up.
Are you either using single-point or selecting the AF point? If you let the camera select AF points, then you're very likely to have it focus on the most contrasty part of the subject, rather than your goal.
I switch between 9-point and single-point, depending on the background and/or subject. For a bird against blue sky, I'll use nine-point. I'll use single-point on the eye for most everything else. I'm on AI servo (fast) most of the time, but switch to single shot for portraits, landscape and other subjects not likely to run or fly.