just got 7d, I am really frustrated right now.

Started Aug 27, 2012 | Discussions thread
Keith Z Leonard Veteran Member • Posts: 6,061
Re: Don't blame the camera

That is a bit silly, sorry to say. The 17-50 is just fine in servo. The difference is that contrast detection uses a measurement of the actual image to determine when it is in focus where as phase detection uses a beam splitter and compares the beams.

PDAF requires calibration between the camera and the lens, problems usually happen there. A lens can be within spec on one edge while the camera is within spec at the other edge and it's enough to throw things off. MFA is useful in this case unless you are off by more than it can handle. I would assume that the range of MFA is related to Canon's spec range, so in that sense you could have more issues with 3rd party lens providers who may not even be aware of what that range entails.

 Keith Z Leonard's gear list:Keith Z Leonard's gear list
Canon EF 70-200mm F4L USM Canon EF 100-400mm f/4.5-5.6L IS USM Sigma 50mm F1.4 EX DG HSM Canon EF 24-105mm f/4L IS USM Canon EOS 400D +16 more
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