Comments about Canon Canon 82mm Multi Coated Circular Polarizer Glass Filter:
I use it on my Canon TS-E 24mm f/3.5L II lens. On a clear day with blue sky, it can darken the sky as it supposed to, and the results have more saturated blues. Its slim design also makes it suitable for wide angle lenses, though on a wide angle TS-E lens, the vignetting is inevitable, when it's shifted.