The polarizer is mainly used outdoors during sunny conditions. It helps to enhance colours and deepens the blue of the sky or water. Various effects can be obtained by rotating the filter. Polarizers are also used to reduce glare on reflective surfaces like glass or water. Circular polarizers work well with exposure automatic and autofocus of digital cameras. Although many effects can be digitally simulated, it is not possible to polarize light in post-processing of photographs. Therefore the use of a polarizer is highly recommended for all cameras. Improve colours and contrast. Reduce reflections high quality glass with metal frame 52mm thread on both sides this circular polarize (CPL) works with autofocus and automatic exposure. The two sample images on the right were taken in sequence, one with polarizer, one without - early afternoon with strong sunlight.