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I recently bought a Canon EF 24-70/2.8L to use with my 450D and I suspect that it is constantly back focusing. Is there any way of determining if it is something wrong with the lens or if it is a problem with my technique/camera?

I suppopse I could send the lens to Canon for calibration, but before I do that I want to make sure it will actually help.

K''
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Mathias
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  • can you describe backfocusing? I'm not familiar with the concept. – reuscam Jul 15 '10 at 20:13
  • Is your question the same as http://photo.stackexchange.com/questions/1/what-is-the-best-way-to-micro-adjust-a-lens ? – Reid Jul 15 '10 at 20:20
  • I find them very similar but the related question is specifically asking for instructions on how to fix problems with autofocus, not how to find them. Maybe this question could be formulated to encompass more problems with autofocus than just back focusing. – Mathias Jul 15 '10 at 20:31
  • possible duplicate of What is back-focusing? – mattdm Mar 23 '11 at 03:12
  • http://photo.stackexchange.com/questions/900/what-is-back-focusing is a slightly newer question, but it got some good answers where this one (too specific?) didn't. See also http://photo.stackexchange.com/questions/1/ for correcting the problem (on higher-model cameras). – mattdm Mar 23 '11 at 03:14

1 Answers1

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To check if your camera/lens is having front-focus or back-focus issues you can download a pdf (incl a focus chart) here:

http://focustestchart.com/focus21.pdf

The interesting stuff starts at page 13.

Marc
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