This filter uses the B+W XS-Pro Digital mount which is especially suited for DSLRs with wide angle and zoom lenses. The XS-Pro HTC Kaesemann MRC2 Nano Circular Polarizer filter mount measures only 5mm in thickness. Industry leading B+W uses only the highest quality German Schott glass for outstanding results every time.
B+W Kaesemann Circular Polarizers are well suited for applications that require the highest possible imaging quality "Optical Flatness", especially with high-speed telephoto and apochromatic lenses.
The Kaesemann filters have a higher efficiency than conventional polarizing foils and they are cemented between high-grade plano-parallel optical glass. The resulting sandwich is then precision-polished again to achieve highly accurate plano-parallel surfaces. This is very important for use with telephoto lenses. The Kaesemann Circular Polarizers are then edge-sealed to protect the foil against humidity.
The nano coating is an outer layer of protection that comes standard with all XS-Pro Digital nano MRC filters. The nanotechnology based characteristic (lotus effect) produces a better beading effect with water, making the cleaning of this filter even simpler and faster than ever before. The MRC nano coating has an improved outer (8th) layer over regular MRC coatings.
For this high-end polarizing filter, the foil pieces are selected individually for maximum color neutrality. Following cementing between high-grade optical glass, additional grading and polishing takes place. This guarantees outstanding sharpness even with very bright, apochromatic lenses. These latest cementing technique ensures lasting stability even in damp climates. The filter extension factor is only 2 to 3, equivalent to approximately 1 to 1.5 f-stops.