Polarizer reduces glare and unwanted reflections, improves contrast, penetrates haze at long distances, deepens blue skies, and helps maintain color saturation.
The effect of a polarizer lies in the transmission of only certain planes of oscillation while absorbing others. By rotating the polarizer can be adjusted to the wanted effect strength. Polarizers allow only perpendicular waves to pass the filter so there is some light loss depending on the orientation of the filter.
Circular polarizers are ideal for use with digital cameras and autofocus lenses where a linear polarizer will often disrupt auto exposure and focus features. A circular polarizer darkens skies and provides color and contrast enhancements. One-stop polarizer are ideal for shooting in low light situations such as indoor or at night, where polarization is still needed and no more than one stop light loss is important