Originally posted by JBox I used a polarising filter the other day and saw no problems in the viewfinder turning it all the way around.
You used a circular polarizer correct? Try flipping it over and rotating it while look through the viewfinder. It might be easier holding the filter over the viewfinder and looking through the filter. Or if you have a linear polarizer try that instead.
Circular polarizers are weird. They blackout other polarizing filters when viewed from one direction but not the other.
For fun look at you flat screen monitor through the circular polarizer and then flip the filter over. A linear polarizer blacks out from either side.
Fun with optics!