Cokin 67mm Wide Angle Circular Polarizing Glass Filter (Round) - Light rays which are reflected become polarized. Polarizing filters are used to select which light rays enter your camera lens. They can remove unwanted reflections from non-metallic surfaces such as water or glass, and also saturate colors providing better contrast.
Cokin Wide Angle Circular Polarizers feature thinner glass and a thinner ring. This design minimizes vignetting, a feature where the corners of the filter actually "intrude" into the corners of the frame and show up as black areas.
The effect can be seen through the viewfinder, and changed by rotating the filter. The filter factor varies according to how the filter is rotated, and its orientation to the sun.
Cokin filters are used worldwide. Cokin produces an incredible variety of filters for special effects and image manipulation—practically any effect you may desire or need. From soft effects for portraits, color enhancement for landscapes and color correction for architectural and lighting photography, Cokin makes a filter, in different grades, to suit your needs.
In addition, Cokin offers filters in different size categories, i.e. "A", "P", "X" Pro and "Z" Pro. These classes of filters are designed to meet the needs of pro and amateur photographers and videographers who need special effects filters in various sizes.