Light rays which are reflected by any surface become polarized and polarizing filters are used to select which light rays enter your camera lens. PL-CIR (Circular Polarizing) filter is important for your camera. It allows you to remove unwanted reflections from non-metallic surfaces such as water, glass etc. It also enables colors to become more saturated and appear clearer, with better contrast. This effect is often used to increase the contrast and saturation in blue skies and white clouds. Hoya's polarizing filters do not affect the overall color balance of a shot.