Polarizers provide color and contrast enhancement. Reflected light shows up in the image as whitish glare that washes out the color in an image. A Polarizer corrects this problem and produces 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 SLR's (for most 35mm auto-focus cameras see your camera manual).