ATHABASCA HD CPL (W) Filter 150mm Athabasca HD CPL, high definition circular polarizer, is mainly used to increase color saturation, darken blue skies so white clouds stand out, and eliminate reflections from non-metallic surfaces like glass or water. It will also reduce the softness in scenery caused by atmospheric haze. This filter will not change the overall color balance of a photograph. Using Japan imported optical glass and top quality Japan polarizing films and with secondary advanced operation, Athabasca HD CPL is certain to achieve super HD effect. How to Use: Fix the HD CPL directly to the front lens, rotate the HD CPL and observe the polarized light source through the LCD or viewfinder, until the polarized light weakens or disappears as expected. Materials: Environmentally oxidized aviation aluminum Raw materials: Japan imported optical glass & polarizing films Technology: Advanced HD processed