Hoya HD Circular Polarizer

The light rays that are reflected are polarized Polarizing filters are used to select the light rays that enter your camera lens They can eliminate unwanted reflections from non-metallic surfaces such as water or glass and also saturate colors providing better contrast The effect can be viewed through the viewfinder and changed by rotating the filter The filter factor varies depending on how the filter is rotated and its orientation to the sun.

Note circular polarizers are designed specifically for use with autofocus SLR cameras (they will also work on manual systems and video cameras without problems).