77mm Slim Kasemann MRC Circular Polariser Filter further details
Slim
This filter uses a Slim-Line mount for wide angle lenses. It's The height is only 5mm and it does not have a front accessory thread to avoid vignetting with lenses as wide as 17mm in 35mm format, and some photographers report success with lenses as wide as 16mm. A slip on lens-cap is supplied with Slim filters.
Käsemann
The “high-end” polarizing foils of the Käsemann-type filters are neutral in colour, they 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. Subsequently they are edge-sealed to protect the foil against humidity. Discriminating photographers regard the B+W Käsemann-Type Polarizing Filter to be the very best of all polarizing filters. They are well suited for applications that require the highest possible imaging quality, especially with high-speed telephoto lenses and apochromatic lenses.
MRC
MRC (Multi-Resistant Coating) by B+W is not only an extraordinarily effective multiple layer coating, it is also harder than glass, so that it protects filters from scratches (for instance when cleaning the filters), and it is also water and dirt repellent, thus facilitating filter maintenance.