AF system of my trusty 7D is not working properly?

Started Jun 3, 2012 | Discussions thread
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Jaims
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AF system of my trusty 7D is not working properly?
Jun 3, 2012

Hi all,

a couple days ago I just noticed that the AF system of my trusty 7D is not working as it should...

The malfunction only happens when using AI servo with all AF points, and I try to engage focus with central point; being the subject a BIF at a distance that makes the subject to fill just a small area of the frame.

The normal behavior should allow the AF system lock on the subject with the central point, and then, as the bird moves in the VF, AF continues locked on it by means of any of the other AF points if needed.

That would be normal behavior; but what I've found is that focus simply won't lock with the center AF point, the focus starts to hunt, and in the end the AF stops trying to lock and 1 AF point (always the same, the one in the bottom right corner) is displayed in the viewfinder).

In other words, when using AIServo+all AF points, the center AF point has a hard time trying to lock focus, an 8 out of 10 times it won't lock, AF system will hunt, and finally will give up (the same outer AF point will be displayed in the VF when the focusing dies).

Now the thing is that if I use AIServo+all AF points with something that fills the frame and it is more contrasty than a far BIF in the sky, AF system will work as expected.

And if I try to track a BIF using only central AF point or central + surrounding points, the AF system works perfectly.

The subjective feeling is that when in AIServo+all AF points, the central AF point is less sensitive than it used to be and misses the subject, then starts the hunting and in the end it defaults to one of the surrounding AF points before to die.

Does it all make any sense? Any ideas that come to mind?

TIA

 Jaims's gear list:Jaims's gear list
Canon EOS-1D Mark III Canon EOS 5D Canon EOS 7D Canon EF 35mm f/2.0 Canon EF 50mm f/1.2L USM +9 more
Canon EOS 7D
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