Quote Originally Posted by Dr Croubie View Post
Just a word of caution about buying a cheap one and/or just sticking two CPLs together back-to-back (or is it front-to-front?). At very-low and very-high filter factors, you can get a colour cast, I've tried building my own and managed to get it at a point of the whole shot going rather green or rather purple.
I know of polarizers that got a colour cast. But that colour cast only at low and high densities you describe puzzles me.