67mm Circular Polarizer Multicoated Glass Filter (CPL) for Canon EF-S 17-85mm f/4-5.6 IS USM + Microfiber Cleaning Cloth This filter eliminates ultraviolet rays from outdoor shots as well as polarizing the light to remove reflections, and increase color saturation, without affecting the overall color balance Can dramatically enhance a blue sky and make the clouds more prominent Used best at right angle to the sun Effective with cameras that use beam splitters in the path of the TTL light meter and with AF cameras Along with a UV or Skylight Filter, a polarizing filter should be a part of everyone's gear bag. It can turn a run-of-the-mill image into a stunning, creative photo by increasing color saturation.