This polarizing filter is used to increase colour saturation, darken blue skies so white clouds stand out, and eliminate reflections from nonmetallic surfaces like glass or water. It will also reduce the softness in scenery caused by atmospheric haze. This filter will not change the overall colour balance of a photograph. Most modern SLR cameras use a polarizing half mirror (split beam metering) system and the Circular PL is designed to be used with them. Filter factor: 3-4 or 1 2/3 to 2 stops
In general, light reflected from water, glass, or other shiny materials is polarized and adversely affects image definition. Kenko's Circular polarizing filters reduce or eliminate unwanted reflections and increase the overall contrast of subjects in low-contrast situations. Usually, light from the sky is polarized due to reflections and dispersions in the air. Circular polarizing filters cut these reflections, making the sky blueror intensifying colors.
For more information about, Kenko 49mm Digital Circular PL Polarizing Filter .