The B+W 55mm XS-Pro Kaesemann High Transmission Circular Polarizer MRC-Nano Filter helps to reduce reflections and glare by filtering out light that has become polarized due to reflection from a non-metallic surface.  A polarizing filter arranges, and filters, this directionally polarized light perpendicularly to the reflected light, allowing for the absorption of much of this light. This results in a noticeable reduction of glare and reflections from non-metallic surfaces and an increase in the saturation of skies and foliage.. The addition of this quarter wave plane is to circularly polarize the linearly polarized light for the use of auto focus and exposure functions. Due to how the light is broken down and filtered with a linear polarizer, auto focus and exposure accuracy become skewed during use. When the light becomes circularly polarized, it permits the use of these functions.The resulting sandwich is then precision-polished to achieve accurate plano-parallel surfaces. Finally, they are edge-sealed to protect the foil against humidity. 

The Nano coating associated with XS-Pro filters provides an additional eighth layer over the MRC, resulting in an improved beading effect when in contact with water for greater cleaning efficiency.To further reduce the possibility of vignetting when this filter is in use, the filter ring's outside diameter is slightly larger than the actual thread size. This may prevent the use of some lens manufacturer bayonet hoods.Polarizing filters arrange, and filter, directionally polarized light perpendicularly to the reflected light, allowing for the absorption of much of the light.Circular polarizers are ideal for use with digital cameras and autofocus lenses where a linear polarizer will often disrupt auto exposure and focus features.Nano coating provides an improved beading effect with water for more efficient cleaning.

B+W XS-Pro Specs