The B+W 49mm Circular Polarizer MRC Filter helps to reduce reflections and glare by filtering out light that has become polarized due to reflection from a non-metallic surface. This results in a noticeable reduction of glare and reflections from non-metallic surfaces and an increase in the saturation of skies and foliage. A circular polarizer only differs from a linear polarizer in that it contains a quarter wave plane in addition to the linear polarizing filter. Due to how the light is broken down and filtered with a linear polarizer, autofocus and exposure accuracy become skewed during use. When the light becomes circularly polarized, it permits the use of these functions. Additionally, it offers greater protection to the filter substrate and stays cleaner for longer than uncoated filters. Helps to reduce reflections and glare by filtering out light that has become polarized due to reflection from a non-metallic surface. Circular polarizers are ideal for use with digital cameras and autofocus lenses where a linear polarizer will often disrupt auto exposure and focus features.