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Old Aug 17, 2010, 10:27 PM   #1
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Default Communication problems between K20D and Sigma 70-300

On our recent trip to Grand Manan Island I attached my Sigma 70-300 APO DG lens onto my K20D body. I've used the lens many times before, but for the first time, the camera body asked for me to input the focal length of the lens. I wasn't sure what to put, since the zoom range is considerable. In the end I think I input 250mm, assuming i was more likely to use the lens near the long end.

I was thrilled when a bald eagle flew by and perched in a nearby tree. But I was disappointed with the blurry photos I got. This is the best of about 20 pics I took. All shots were hand held, with SR on.

Anybody have any ideas on why my camera all of a sudden couldn't tell what lens was attached? And do you think this body/lens communicstion issue might be the cause of the poor focus?
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Old Aug 18, 2010, 2:22 AM   #2
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Did you try detaching and then reattaching the lens ? Maybe the contacts need cleaning ?

It could well be the reason for the blur since the camera will be compensating for 250 not 300 if that is what you shot at.
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Old Aug 18, 2010, 7:22 AM   #3
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Sometimes removing the battery and re inserting it can reset the camera if it gets fouled up. A low battery could also cause it to misbehave, try a freshly charged battery. Make sure the camera is still set to AF.

Lou

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Old Aug 18, 2010, 9:26 AM   #4
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I hope it is something simple, but I had the same issue a couple of years ago with my Sigma 50-500mm. It had been working fine and then one day it asked me to set the focal length as if it was a manual lens. Removing and reattaching the lens seemed to help for awhile but it would crop up more and more frequently. There was a very slight play in the mount and I found if I put slight pressure on the lens it would then be read properly by the camera. Since the lens was under warranty I sent it in to Sigma and they found that there was a short in the contacts on the mount, they fixed it and I had it back in less than a week. Of all of my lenses I use this one the most and it has worked perfectly ever since.

Steve
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Old Aug 18, 2010, 11:21 AM   #5
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I have the same problem with the same lens on my K-7, it worked perfectly on my K10D, but the K-7 refuses to recognise it more often than not.
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Old Aug 18, 2010, 10:12 PM   #6
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Thanks for the replies folks. I'll clean the contacts and recharge the battery. It would be wonderful if that solved the problem.

Tachikoma, I'm very interested to hear that your K7 deos the same thing with the same lens. Seems odd that with both your K7 and my K20, the camera sometimes recognizes the lens, and sometimes doesn't.

I didn't put this in my original post, and I don't know if it makes any difference, but I was quite a distance from the eagle. The shot I posted has been cropped; it probably represents half the frame, maybe less than half. But that lens usually performs much better than this. The shot of the whale's tail in my Grand Manan Island thread was taken with the same lens and was cropped even more extremely, and is still quite sharp.
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Old Aug 19, 2010, 2:26 AM   #7
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The lens behaves better with the new firmware update for the K-7, so I assume it's purely a software issue, have you checked if your camera has the latest firmware?
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