However.... a wide-angle takes in enough swat of sky to have a varied polarization pattern over the width of the lens. You might have, for example, maximum extinction on one side and almost no extinction on the opposite side.
If you're shooting digital, make sure you get a circular polarizer.
Not in my opinion. I firmly believe that a bad filter is generally worse than no filter at all.So I'm guessing that the cheap Sunpak circular polarizer bought for me at wal-mart isn't a good one to use? Obviously there are better out there, but is it better than not having one?