Hoya Pro1D Circular-PL
Color and contrastenhancement   Light rays which arereflected by any surface can become polarized so polarizing filters areused to select which light rays enter your camera lens. CIRCULAR PLfilters allow you to remove unwanted reflections from non-metallicsurfaces such as water, glass etc. They also enable colors to becomemore saturated and appear clearer with better contrast. This effect isoften used to increase the contrast and saturation in blue skies andwhite clouds. HOYA's polarizing filters do not affect the overall colorbalance of a shot. Reduce Glare andReflections with the CIRCULAR-PL   Using the CIRCULAR PLfilter, reflections and glare can be reduced significantly fromnon-metallic surfaces. A camera angle of 30 degrees from the reflectingsurface (glass, water, etc.) is ideal for maximum effect.