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Old Jun 17, 2006, 10:49 PM   #1
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Hi Maxxum 7D users,does anyone uses a Sigma 18-125mm DC lens with circular pol filter on their 7D, and receives a very obvious vignetting? I recently bought the 7D, and had a variety of problems (at this time still thinking/hoping that it is related to the lens)...Anybody had similar problems and knows some answers for that (or)deal?Supposedly the Maxxum has an APS-C sized CCD and therefore that vignetting should not be an issue - however it is clearly there...Any thoughts/suggestions/experiences are very welcome!Thanks,Ningaloo
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Old Jun 17, 2006, 11:11 PM   #2
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Doing some quick digging around, I found some complaints about vignetting from this lens (Canon owners, Minolta owners, etc.) at wide open apertures.

Yes, the KM has an APS-C size sensor (but this lens is designed for smaller sensors so the image circle is smaller, too). So, it's more likely to have vignetting compared to a lens designed for 35mm cameras (then, you'd be using the "sweet spot" of a lens with a DSLR).

A polarizer is going to make vignetting much more obvious, and if you're not using a thin filter, the filter itself can cause some vignetting.

I'm seeing owner comments about vignetting from this lens as being anywhere from a minor annoyance to terrible and totally unacceptable. I found one user that said using thin filters didn't seem to help much either.

Here is a Canon owner showing it (note the vignetting in the 18mm f/3.5 shot (image sample number 10 on the botom row). The other wide open samples (even at longer focal lengths) on the bottom row also show some vignetting.

http://homepage.mac.com/aozer/18-125/18-125.html

Stopping down your aperture a bit from wide open should help it.

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Old Jun 17, 2006, 11:23 PM   #3
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Hi Jim,Thanks for your fast answer on this.*Well - its supposedly a lens specifically build to fit the digital Maxxum Series (thus only the 5D and 7D?) - but if it is build for smaller CCD sizes, than they didn't do a good job in getting the correct size for the CCD used in the MAxxum cameras.*I have a normal-sized pol filter, but even my thinner UV filter show up with some vignetting at 18-25mm ...Will have to see how to handle that problem....Anyway, thanks for the link and the comments - it will help!*Ningaloo
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Old Jun 17, 2006, 11:33 PM   #4
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Well, most of the Canon DSLR models have a slightly smaller sensor compared to the KM 5D and 7D, and Ifound Canon owners complaining about it, too. Thesamples in the link above were shot with a Canon EOS-20D.

It's not really designed specifically for a KM DSLR. It's designed for Pentax, Sigma, Canon, Nikonand Konica Minolta DSLR models (the optics are the same, onlyit's available in multiple camera mounts).

So,thevignetting appears to be a characteristic of this particular lens at wider apertures (probably trying to make it a bit too small and compact for it's focal range and apertures available). ;-)



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