Marumi DHG Circular Polarising Filter 40.5mm is specially designed for digital cameras and well suited to use with wide-angle lenses and enhance picture quality by blocking harmful reflected light. The Sigma filter is an essential accessory for outdoor photography and fits to selected lenses with a 40.5mm filter thread. The Ultra-low reflective coating for digital cameras to eliminate flare and ghosting up to negligible level and smooth frame helps minimize reflection off internal CCD and CMOS sensors. The filter is equipped with improved antireflection coatings and the glass edges are blackened to avoid internal reflections. The polarizer helps make a blue sky more bluer as well as making clouds stand out. The effect can be seen through the viewfinder and changed by rotating the filter. The filter removes unwanted reflections from non-metallic surfaces such as water or glass and also saturates colors providing better contrast. The filter protect front lens surface from dust, scratches, dirt and fingerprints. It provides fabulous shot of a cloud filled sky or make the water seem more saturated.