The 7Ds amazing autofocus system
I made crops of a burst of 9 BIF shots showing how the autofocus points changed frame by frame. Elapsed time was 1-2 seconds. The 7D nailed all but one shot.
The sequence showing the changing autofocus points can be viewed as a slide show here:
I think it's pretty amazing. The autofocus points changed 8 times in that short time span. On some shots the active point wasn't on the subject at all, but the subject stayed in focus. I'm assuming this is because of a very short delay in releasing a point when a subject moves away from an autofocus point (e.g a wing was on a point when focus was acquired but off of the point when the frame was exposed).
One of my favourite shots from the burst:
7D + 400mm f/5.6L, focus limiter at 8.5m
1/2500, f/6.3, ISO400 - manual mode
AI Servo - all autofocus points active
Tracking sensitivity - default (0)
AF priority/Tracking priority
Main Focus point priority