The 7Ds amazing autofocus system

Started Jul 10, 2010 | Discussions thread
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jameslj
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The 7Ds amazing autofocus system
Jul 10, 2010

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:
http://www.flickr.com/photos/jameslj/sets/72157624460132860/show/

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:
http://www.flickr.com/photos/jameslj/4760476167/sizes/l/

Burst details:
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

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