The B+W 49mm XS-Pro Kaesemann High Transmission Circular Polarizer MRC-Nano Filterhelps to reduce reflections and glare by filtering out light that has become polarized due to reflection from a non-metallic surface. The light from the sun naturally becomes partially polarized due to reflecting off electrons in air molecules, causing the light to scatter into what appears as haze. 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.
A circular polarizer only differs from a linear polarizer in that it contains a quarter wave plane in addition to the linear polarizing filter. 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.
Kaesemann High Transmission Circular (HTC) polarizing filters are fitted with polarizing foils which provide 99.5% light transmission that are cemented between plano-parallel optical glass. The resulting sandwich is then precision-polished to achieve accurate plano-parallel surfaces. Finally, they are edge-sealed to protect the foil against humidity.
To prevent internal ghosting and reflections, each glass surface includes multiple layers of anti-reflection coating. This Multi-Resistant Coating (MRC) also offers further protection to the filter substrate and helps it to stay clean for longer than with uncoated filters. 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.
B+W filters are constructed from Schott glass for increased optical clarity and color fidelity. This filter features a thin brass filter ring to minimize the potential for vignetting while enhancing durability and jamming prevention. 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.