Filters can help produce better photos. However, the quality differences between filters are huge. If you have an expensive lens, you do not want to run the risk of image quality losses due to inferior filters. The glass used must be homogeneous. Both surfaces must both be “plan parallel”. Otherwise they will produce blur due to different light refraction. The surfaces must be smooth and free of scratches. The polish must be equal to that of the surfaces of camera lens elements so as not to cause any contrast-reducing scattered light. Black anodized brass rings are used for HR Digital UV Blocking filters with Super Multi-coating because they have a high mechanical strength. They will not bind when using two or more filters at the same time on the same lens. The glass edges of all Rodenstock filters are blackened so that no contrast-reducing reflections are caused there. Rodenstock UV blocking filters block the UV radiation with a steep flank exactly at the border to visible light. Rodenstock UV filters have perfect color neutrality and make ideal protective filters, protecting the front lens element against dirt. They can be cleaned more easily than the lens element and protect the front lens element against scratches and blows. The UV blocking filters of the HR Digital line also have a water-repellent coating at which water rolls off. Oil, fingerprints and other contamination adhere less. This nano-coating is even more scratch-resistant than the MC coating. Rodenstock UV blocking filters are also free of vignetting with wide-angle shots because they have a slim line frame, which includes a front thread.HR Digital UV Block with Super Multi-coating filters have: The best optical glass A perfect optical surface quality Multi-coatings with a high light transmission rate An extremely scratch resistant coating Are liquid and dirt-repellent coated A rugged slim brass ring with front thread Are compatible with most wide-angle lenses