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Old Sep 27, 2010, 7:22 PM   #21
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yea the upper corner is just too extreme. seems to be a very decentered lens, i would have it repaired/replaced.
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Old Sep 28, 2010, 3:17 PM   #22
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I got a replacement today. This one is much better. However, once out of many pictures I took 15mm f22, I got a semi small dark upper right corner, but still not even close to what I was getting previously.
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Old Sep 28, 2010, 3:46 PM   #23
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I'm pleased that this one is working out better, but I remind you that the diffration limited f-stop for the 50D is about f/16, so you probably shouldn't be using apertures smaller than that anyway.
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Old Sep 28, 2010, 3:47 PM   #24
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well the good news is there is no reason to shoot at f22, esp at 15mm. you get plenty of dof at bigger apertures at that focal length for anything you will do, not to mention the diffraction is going to be pretty bad at f22.
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Old Sep 28, 2010, 3:57 PM   #25
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Thanks guys. I really appreciate your comments. When I went to the store and the guy checked it he immediately told me that it looks awful and handed me a new one. I am just trying out f22 because there is easiest to spot these errors. I do not plan to shot at f22, and probably not f16 either.

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Old Sep 28, 2010, 4:40 PM   #26
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Quote:
Originally Posted by TCav View Post
I'm pleased that this one is working out better, but I remind you that the diffration limited f-stop for the 50D is about f/16, so you probably shouldn't be using apertures smaller than that anyway.

Excellent article. Thanks. Live to learn.
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Old Sep 28, 2010, 5:18 PM   #27
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Quote:
Originally Posted by Shompis View Post
... When I went to the store and the guy checked it he immediately told me that it looks awful and handed me a new one. ...
Go back there and buy more stuff. He deserves as much custom as you can send his way.
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Old Oct 1, 2010, 6:26 AM   #28
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Do you have the hood on and on correctly? Is it the right hood for this lens? This looks to be more of an obstruction than vignetting. Vignetting is gradual fall off in the corners and this diplays a sharp contrast at the point where it starts. The fact that it happens only on the wide end substiates obstruction of the field of view. This lens is known to have vignetting wide open but the samples provided do no show vigentting, with this lens wide open all vignetting is normally non existant when stopped down to f8 wide open. Here is a sample image of vignetting with this lens which clearly demonstrates that this is not what you are experiencing.

http://www.the-digital-picture.com/R....aspx?Lens=675
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Old Oct 1, 2010, 4:03 PM   #29
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I had no filter or hood attached.

I agree, this does not look what you expect from vignetting, even assymetric vignetting. Something internal is obstructing it or lens circle is misaligned. I have seen pictures here on this forum I believe where people attached lenses made for APS-C sensors on fullframe and you got a very similiar result. So it seems that some of the light (or lack of light?) that hits the sensor never goes through the lens properly at all. By the way, I got it replaced. Much better copy, but still not perfect.

Last edited by Shompis; Oct 1, 2010 at 4:05 PM.
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Old Oct 3, 2010, 9:36 AM   #30
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For the $$ this costs I would keep going back until I got one that didnt do this, or send to Canon service. Not much use in wide angle is you cant use it. The only other alternative is to go to EF lenses, you wont get the same range but you will never get this problem as the sensor will only see the sweet spot of the glass.
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