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Old May 13, 2006, 4:20 PM   #51
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And left side:


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Old May 13, 2006, 4:28 PM   #52
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GM2006,

I've already done the upside down test and it's still blurry on the same area. The lens is really a new lens, I've checked the serial number.

The camera body I've been using for almost a year and I've never seen any blurring. On the other hand, I still don't see any significant blurring with the kit lens so if there's really something wrong with the body I wouldn'thave recognized itbefore mounting the wide angle Sigma which I bought one week ago.

With the kit lensthe picture isquite okay.

What I can say today is that the combination of my 350D (DR XT) and the Sigma 10-20 definitely causes softness on the right side of the picture. With the kit lense or my Sigma 70-300 there is no significant blurring.

I don't need to do any testing anymore to see if there is blurring because there IS blurring. What I need to do is to check the lenses mounted on the 30D. Then we will see what's thecause of the blurring. The 30D has the same sensor as the 350D thus any fault of the lens shouldshow up.

fisheye
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Old May 17, 2006, 4:38 PM   #53
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Today, I checked the Sigma 10-20 with an EOS 30D and I found exactly the same effect.

I went to the dealer and after some shootings, checkings and a lot of discussions I exchanged it against a Canon 10-22 and paid the difference. It's working fine and the overall quality is better than the Sigma, I've definetely checked that.

I've learned my lesson.

Thanks everybody for the help.

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Old May 17, 2006, 4:44 PM   #54
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Final example, no more need to say or post from my side. chapter closed.


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Old May 17, 2006, 7:09 PM   #55
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I am glad you finally finished with your trouble. Somewhere on the internet I've read that there is 'a batch' of Sigma 10-20 (someone said it is an 'early release') that was not up to standard. It is possible that your shop had those and that you were extremely unlacky.Canon lens purchase proved that it was definitelly a 'bad Sigma'. I think we all learned a bit from your bad experience ... So reports and experiences from the internet cannot be always ignored. :idea:

Still, there are number of happySigma lens users.
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Old Jun 13, 2006, 7:19 AM   #56
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I bought this lens from Jessops (UK) about a month ago, and it had the identical soft RHS problem. Took it back and tested another lens in the shop, which showed the identical problem. Jessops offered to return the lens to sigma for repair, which I accepted.

Sigma said the lens couldn't be repaired in the UK, and they would send out a replacement, which I have just collected.

I can't believe that the new copy has the identical problem. You start to wonder whether it can be the camera. If I manually focus, I can get the right hand side in focus, but the left hand side goes out of focus (at close range). In the distance, the depth of field means that it's permanently right-hand side soft.

I'm running out of options -- I can't afford the Canon lens, the left hand side of the Sigma is superb, I just want a lens that works.
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Old Jun 20, 2006, 1:17 PM   #57
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My dealer claimed that the reason is because the Sigma is inferior in quality (it has less corrective glass elements) and therfor it can happen that one side is soft. He explained that this happens if the object in focus or the sensor in the camerais not exactly 100% plane.

I cannot judge on that opinion. Some points sound logical to me and I know that the Canon has some more pieces of class inside but it doesn't explain why it is always the right side which is blurry.

I don't know. I solved it by buying the much more expensive Canon.

The thing is, if you send your lens back to Sigma and they cannot find anything because the "softness" is due to the construction of the lens and not due to a misaligned glass element than you've lost a lot of time and will loose much more time arguing with Sigma or with Canon (perhaps the sensor is not plane).

I decided that I don't have the time to discuss with either Sigma or Canon.

Regards,

Fisheye
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Old Jun 20, 2006, 4:33 PM   #58
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My brother bought the Sigma 10-20 a couple weeks ago and its flawless. I guess its luck of the draw.
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Old Jun 20, 2006, 4:42 PM   #59
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Fisheye wrote:
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My dealer claimed that the reason is because the Sigma is inferior in quality (it has less corrective glass elements) and therfor it can happen that one side is soft. He explained that this happens if the object in focus or the sensor in the camerais not exactly 100% plane.
That sounds like a bunch of bull to me. A manufacturer isn't going to design a lens that's only soft on one side.

Did you ever test the lens using Newspaper to see if it was equally soft in all 4 corners?

A lens that wide isn't going to have a flat focus plain. It's just too expensive to manufacturer a lens as wide as this one that way. But, it should be equally soft in all 4 corners, *if* you have the camera square to your target (and your samples don't give me the impression that you're trying very hard to test it that way).

If it's not equally soft in all 4 corners, shooting with the camera square to a target like a newspaper (where you don't have varying distances to the corners), then you've got a lens problem (likely a misaligned element), or a camera problem (misaliigned sensor).

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Old Jun 20, 2006, 10:13 PM   #60
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When in doubt always check the MTF's:
http://www.photozone.de/8Reviews/len..._456/index.htm
http://www.photozone.de/8Reviews/len...3545/index.htm
-> now which one is superior (... and worthy of the $)??? :idea:
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