Kenko E-Series Circular Polarizer is used to increase color saturation. It darkens blue skies so white clouds stand out. This filter eliminates reflections from nonmetallic suraces like glass or water. It will also reduce the softness in scenery caused by atmospheric haze. It will not change the overall color 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.