stop the vingetting on super wides

[Mountain Man]

Is there a CP polarizing filter out there that would not cause vingetting on a sigma 10-20 wide angle zoom. Let say at the 10mm focal point. Do slim filters work to prevent that vingetting problem?:confused:

[Tsmith]

Are you experiencing an issue with one? POTN member Lightrules (aka: fstopJojo) uses a regular type on his Sigma 10-20mm.

[Mountain Man]

No, but in reading different comments around several forums, some have voiced problems with certain types and or brands. It would seem silly and foolish to me to go out and spend $75.00 to $100.00 dollars on a filter if you couldn't use it all the way down. Of course you could crop it in PP but that is just one more problem to deal with. Why not eliminate the vingetting problem in the begining.:confused:

[SkipD]

While a "thin" CP filter would probably reduce the chance of true vignetting, you will find that blue skies will not be darkened evenly across the image when you use a CP filter with an ultra-wide focal length.

The reason is fairly simple. The amount of darkening blue skies with a polarizing filter varies with the angle to the sun. With an ultra-wide lens, you a very wide angle view of the sky and, naturally, a wide variation in angle to the sun for various portions of the image.

There's no way around this effect except to post-process and manually lighten or darken portions of the blue sky.

[LightRules]

OP, a regular filter (non-slim) does not cause any vignetting at 10mm on the 10-20EX. You can use either a normal or slim version. But, do take note of Skip's comment on uneven skies: it's a plain reality for these UWAs and polarizers.

Toney, I don't use the Sigma 10-20 anymore. Sold it as I just didn't find myself using this UWA too much. Great lens, but just didn't use it, so it's gone.