Filters can help produce better photos. However, the quality differences between filters are huge. If you have a great lens, you do not want to risk image quality loss due to inferior filters. Rodenstock guarantees the best possible filter quality. The optical glass used must be homogeneous and “plan parallel”. The surfaces must be smooth. The polish must be equal to that of the surfaces of camera lens elements so as not to cause any scattered light. The filter frame may not project too far beyond the front edge of the lens barrel so that the filter does not cause vignetting with wide-angle shots. Rodenstock filters have a very flat slim line frame. This allows room for a front thread. The best material for filter frames is brass. Brass rings will not bind when using two or more filters at the same time on the same lens. The edges of all Rodenstock filters are blackened so that no contrast-reducing reflections are caused there. When light is incident on a surface, it is partly reflected. A circular polarizer reduces these reflections. Reflections can be reduced or eliminated at an ideal angle of incidence of around 55 degrees. Reflections can also be amplified up to twice their brightness for more intensive sun reflections on water. The blue light of the sky reflected, e.g. from red roofs, green grass and foliage, is polarized. Landscape shots taken with a polarization filter allow the blue tinge to be reduced producing better color saturation. Blue light from the sky can be intensified using a polarization filter rotated into a suitable. The circular polarization filter requires 1.5 f-stops as a correction.HR Digital Circular Polarizers with Super Multi-coatings have: The best optical glass and perfect optical surface quality Multi-coatings with a high light transmission rate An extremely scratch resistant coating and liquid and dirt-repellent coated A rugged slim brass ring with front thread