The B+W 77mm Kaesemann Linear Polarizer Extra WideFilter 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 linear polarizer only differs from a circular polarizer in that it does not contain a quarter wave plane that enables use of auto focus and exposure features. Linear polarizers are best suited for use with manual cameras, such as view cameras, that are not dependent on internal mechanisms to determine focus or metering settings.
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.
B+W filters are constructed from high quality Schott glass for increased optical clarity and color fidelity. They feature a brass filter ring for durability as well as jamming prevention. The extra wide filters feature an oversized ring that is much larger than the male threads for attachment to the lens. This oversized ring permits the use of glass that is also larger and helps to prevent vignetting when using wide angle lenses. Lens hoods should not be used in conjunction with extra wide filters as vignetting may occur.