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12-15-2008, 07:22 AM   #1
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Sigma 100-300mm F4 Question

I recently bought a Sigma 100-300mm F4 lens and I'm pretty sure it has problems.

It doesn't always register when I put it on my K10D. In other words, when I put it on the camera sees it as a manual focus lens, asks me for the focal length (shake reduction), and won't auto focus. I'm not sure if it's a bad lens of if it's because of the weight of the lens making the contacts not line up. It also doesn't mount securely to the body. There is a little movement when it's mounted but not enough that I'm worried it will fall off the body. Also, the lens exif shows it as a Sigma 70-200mm F2.8 EX.

I'm wondering if anyone else with this lens has any or all of these issues? I'll probably send it back to Sigma for service/replacement when I get home (currently working in Venezuela).


12-15-2008, 07:29 AM   #2
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perhaps you can try wiping down the lens and mount contacts
12-15-2008, 07:35 AM   #3
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Yep, I thought of that first but it didn't do any good. It first happened after I shot some pics near the beach. I thought maybe somehow I had gotten some salt water or sand on the contacts when I was switching lenses. I looked at them and they looked fine but cleaned them anyways (with a cloth, no solvents), no difference.

Also, it's not the camera as I only have this problem with this lens. Forgot to add that in the original post.

12-15-2008, 11:02 AM   #4
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Aside from my copy not focusing to infinity at 100mm, it works great. I've not had it mis-register when mounting it or anything like that. Mine is nice and secure when mounted to the body, no wiggle or anything.

I also see this lens reported as a Sigma 70-200 in Lightroom.

12-15-2008, 01:27 PM   #5
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There was a thread about this a few weeks ago and the general opinion is that it happens with a lot of the larger Sigma lenses.

It does with my 135-400mm but a quick twist usually sorts it.
12-15-2008, 02:07 PM   #6
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Mine works great too other than the problems I've mentioned. I love the photos I've gotten with it so far. I'm going to hate to be without it for however long it takes to get repaired. And mine seems fine at 100mm.

I thought I remembered seeing something on this somewhere but I couldn't remember if it was here or somewhere else. The problem is a twist doesn't seem to fix mine. Maybe it's how I'm doing it. I'll fiddle around with it and see if I can figure out exactly how it needs to be on the body to work properly, the exact position.

I did send an email to Sigma to see what they say about it. Even though it sounds common I don't think it's right.

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