I am looking for a good filter for my 67mm thread lens. I have good experience with the Hoya 8Layer HD cir-pol filter and I really like that it is not as dark as other filters, but it is very expensive and according to reviews it is not as "clean" across the wavelengths and the surface as others like B&W and Heliopan.

http://www.lenstip.com/115.1-article-Polarizing_filters_test.html

http://www.lenstip.com/index.php?art=119

I have come across the Rodenstock filters, but I cannot find any reviews. They are well known for their glasses, so they should be capable of making good camera filters as well?

I value non-filtered transmission (the T1 curve in the tests) and anti glare coating highest in my selection of the filter.