A filter that lets through only light that vibrates in one direction. Light reflected from water, glass, leaves and other non-metallic surfaces is partly polarized. A polarizer can block this light, so it reduces or removes reflections and glare. It can also make a blue sky darker and colors look richer, especially when the sun is at about 90 degrees to the camera.
Most polarizers are circular and screw onto the front of the lens. You rotate the filter while looking through the camera until you see the effect you want. A polarizer also reduces the light by about one to two stops.
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