Tiffen filter - circular polarizer - 67 mm

Polarizers provide color and contrast enhancement. Reflected light often shows up as whitish glare that washes out color in an image. A Polarizer corrects this problem producing deep, dramatically blue skies. It also removes glare from non-metallic surfaces, such as windows and water. Color saturation in general, especially outdoors, can be improved significantly.

A Circular Polarizer has the same effect as a Polarizer and is used on cameras with beam splitting metering systems commonly found on auto-focus SLRs.