B+W's filters are made with a socket made of a brass alloy with excellent physical characteristics and high-purity, distortion-free, thick Schott glass, with particularly precise workmanship, the most modern production technology, in accordance with the highest quality requirements. Finally, each type is provided with a different surface treatment, which completes the perfection of the B+W filters. From the raw materials used to the final touches, 100% "Made in Germany". B+W High Transmission Käsemann circular polar filters (factory code: AUC) radically reduce reflections and increase image color saturation. A polarizing filter is an almost indispensable accessory for outdoor photography. To achieve optimal performance, the filter must be adjusted by rotating its outer part. The correct position can be checked on the search image. When it is used, the natural blue of the sky becomes visible, and the white cloud ruffles stand out. By excluding the reflection of the water surface or glass surfaces, the contents behind them can also be photographed. The High Transmission polar filters cause a light loss of 1 Fe less than other models. This means a huge advantage and a greater freedom factor for the photographer. The Käsemann production technology means the quality developed to perfection in the production of polar filters. When making these filters, the highest quality polar film is used, which is installed in a perfectly flat position between the glass sheets, and then this "sandwich" is glued on the outside and given a matte paint to make it a uniform structure. Dirt and steam can no longer get inside the filter, between the glass sheets. This filter is equipped with eight layers of surface treatment (MRC) on both sides, which, among other things, ensure anti-reflection and dirt resistance. This filter is made with an F-pro mount, which is the B+W standard mount, which can also be used excellently on wide-angle lenses. It is also equipped with a front thread, so an additional filter (e.g. CPL) or accessory can be connected, and the lens caps with internal nails can be used.