Center AF, Offset AF & Liveview comparisons

Started Aug 5, 2008 | Discussions thread
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Tom Meeks
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Center AF, Offset AF & Liveview comparisons
Aug 5, 2008

My XSi's AF has been stellar and downright bad in what appears to be random. At first, I didn't think I had a problem since some images were so spectularly well focused. But, the more I've used it, the more I realized that is is inconsistant.

Following up on an observation that was posted earlier about the outlying AF points working better than the center AF point for Spot AF, I began to observe to see if that were true. If so, it would at least provide a work-around.

I also purchased a 24-70 f2.8L lens to go with the XSi while I wait for the 5D replacement. So, I thought this combination would take any issues that the 'kit lens' might bring to the table. All shots taken on a tripod with the same settings, etc. Here's the result.

First, I focused on the finger and 'R' then moved the camera to complete the shot. Both of the non-LiveView images were shot in the same fashion. Only the point being used changed.

Here is the Center AF Point Result.

Here is the LiveView Result. Notice the distinctly cleaner borders

Now, here is the shot taken with one of the offset AF points. It is just as clean or cleaner than that of LiveView, with nice sharp borders around the dollar amount.

Clearly there is something amiss with the center AF point on my particular camera and I can repeat these results over and over no matter what lens I use. As long as an offset AF works, I'm not bothered all that much about it. But, I'm wondering if a software update can fix such a problem. I'm guessing that it can.

 Tom Meeks's gear list:Tom Meeks's gear list
Canon EOS 5D Mark II Canon EOS 400D Canon EOS 450D Canon EF 24-70mm f/2.8L USM Canon EF 70-200mm f/2.8L IS II USM +1 more
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