The B+W 49mm Kaesemann XS-Pro 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. 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-type filters feature greater optical efficiency than regular polarizing foils and are more neutral in color. The polarizing foils are cemented between plano-parallel optical glass layers, which are then precision-polished to achieve the most accurate plano-parallel surface. This edge sealing protects the filter layers from humidity and are ideal for use with high-speed telephoto and apochromatic lenses.
The Multi-Resistant Coating (MRC) is both an anti-reflection coating as well as a protective surface. It helps to increase light transmission by reducing reflections, scattered light, and ghosting. Additionally, it offers greater protection to the filter substrate and stays cleaner for longer than uncoated filters. The Nano coating associated with XS-Pro filters incorporates an additional 8th layer over the regular MRC and results in a better beading effect with water for greater cleaning efficiency.
B+W filters are constructed from high quality Schott glass for increased optical clarity and color fidelity. This filter features the XS-Pro Digital mount which is specifically designed for DSLR use with wide angle and zoom lenses. The filter ring is made from brass for durability as well as jamming prevention.