B&W Kaesemann Circular Polarizer'sJust as an FWIW, I've been told that the MRC Kaesemann circular polarizers are optically identical to the standard MRC circular polarizers. The difference is the construction. The Kaesemann filters are simply sealed around the edge to protect the polarizing foil against humidity and other environmental conditions.
So, if you live in and never leave the desert, a standard MRC polarizer might be money better spent.
At least, that's what I've been told.
Product Highlights - From B&H photo
Helps to Eliminate Reflections and Glare
Reduces Haze and Blue Cast in Landscapes
Greater Color and Tonal Saturation
High Efficiency Kaesemann Foils <------------------------------Exclusive
MRC Multi-Resistant Coating
Rugged Brass Filter Ring
High Quality Schott Glass
"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."
I've noticed that they don't cool my image as much as the standard B&W polarizers. Its more neutral.