I will be looking for a CP filter for the Zeiss 16-35mm lens. For the A900, I am wondering if vignetting at 16mm wide open will be less with a slim filter as compared to standard filter. I'd prefer to have front threads, but if vigging is a problem that can be lessened I would deal with it.
This may be academic as I would expect to be shooting stopped down when shooting situations call for a CP. But I'm that way. Compulsive and perfectionist.