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Photography Question 

Stephanie D. Moon
 

Focusing Problem


HI, I have been having problems with my Sigma 28-80 f/3.5-5.6 lens on my Canon Rebel XT lately. I noticed the problem became really bad yesterday afternoon when I was taking pictures of my husband and son swimming. When I push the shutter halfway to focus it doesn't do anything (yes it's on autofocus). After about 3 or four times of trying it will finally focus and the next time it does it all over again. I feel pretty confident it's the lens and not the camera b/c other lenses work fine on it. This lens in the past has worked fine also. This lens is about 5 to 6 years old. Is the lens going bad or do I just need to clean the contacts or something?


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June 19, 2007

 

Stephanie D. Moon
  I forgot to mention that I have the focus lock on the center point.


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June 19, 2007

 

Jon Close
  If the lens has worked fine on the XT before, then I'd suspect a bad or dirty connection. Besides cleaning the camera and lens contacts, make sure it is fully and securely mounted with the lock pin clicking in. If its just a bit of a twist off it'll act up.

If the lens has worked fine on film EOS cameras, but is now acting up when used on the digital body, see http://photonotes.org/articles/beginner-faq/lenses.html#compatibilitythirdparty. Sigma 28-80 f/3.5-5.6 (various models) made before 2002 may have faulty ROM chip causing incompatibilities with the latest EOS models.


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June 19, 2007

 

Stephanie D. Moon
  thanks Jon. I was worried about it not working with my digital when I got it but it has worked fine for almost a year until now. Thanks for your info. I will check the contacts. I don't know how to clean them. I'm a bit leary of doing that myself and messing something up. Is that something I can do or should I take it to the shop?


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June 19, 2007

 

Jon Close
  A pencil eraser is good for cleaning electronic contacts, but be careful not to get crumbs in the camera.


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June 19, 2007

 
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