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Auto Focus not Working with Sigma 17-70mm

edited July 2013 Posted in » Canon T2i Forum

I bought a Sigma 17-70mm lens last year. It was fine to begin with, but whenever I have my Canon T2i in auto focus mode it focuses incorrectly, causing the image to be totally out of focus. As a result, I constantly have to keep the Canon in manual focus mode which isn't ideal as this was meant to be my quick multi-purpose lens. I do not have this issue with any of my prime lenses, or the kit lens that came with my original Rebel XSI. Is there a fix for this issue?


  • edited July 2013
    Are you sure you haven't accidentally switched the lens to MF instead of AF?
  • edited July 2013
    No, it's in the AF mode that I have the problem.
    Basically it goes back and forth trying to find something to focus on, and then finally stops with the green square and the happy "beep beep" to say the image is in focus. The result is a totally out of focus image. If I want to use the lens now, I have to put it in MF and focus myself.
  • edited July 2013
    Apart from cleaning the contacts on both the lens and camera body, I am at a loss as to what to suggest. As your other lenses work fine then I think it is unlikely to be the camera. Maybe you should contact Sigma support for any suggestions.
    Sorry, I can't help on this one.
  • edited July 2013
    Hi again.
    I've done some trawling around the internet and it seems you are not alone in experiencing problems with autofocus on this lens. It seems that in most cases, the problem is resolved when the lens has been returned to Sigma. I don't know what costs would be involved if you are out of warranty.
    Regards, PBked
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