Canon Circular Polarizer

Filter polarized as expected, but had two problem areas; 1. It was difficult to keep smudge free. 2. The Canon lens cap from my Canon 17-40 lens would not grab onto the filter's thread. I asked Canon "why?" but the only reply was that "it was designed this way". I was afraid that this left the filter/lens exposed too often, and was proven correct (unfortunately) today - the camera bag fell and the filter cracked, with a cap it may have survived.

Good polarizing with little flare.

as above

Not impressed