Circular Polarizer Filter (CPL) -49mm/ 52mm/55mm/58mm/62mm/67mm/72mm/77mm/82mm Package Including: 1 CPL Filter Note: the filter comes without logo. A polarizing filter, used for both color and black-and-white photography, is colourless and does not affect colour balance, but filters out light with a particular direction of polarisation. This reduces oblique reflections from non-metallic surfaces, can darken the sky in colour photography (in monochrome photography colour filters are more effective), and can saturate the image more by eliminating unwanted reflections. The main function of the Circular Polarizer filter (CPL Filter) is eliminating the scattered light in the air,as well as the reflected light of the metal ,glasses and liquid.It is only allow the parallel light through the lens only,so that the camera can get a better picture such as blue sky,white cloud,clean water and so on. When you rotate the CPL filter in its mount, the effects will show up immediately.