Especially recommended for autofocus cameras.B&W Filters: Worthy of the Finest Lenses B&W filters are manufactured in the style of the best optical lenses. Each filter is cut from raw cylinders of pure Schott/ Mainz optical glass, the same glass used by the world's top lens manufacturers. The filter mounts are made from black anodized solid brass. These high-quality components, combined with B&W's modern production technology & rigorous quality control, produce the flattest possible filters. This precision flatness (plano-parallelism) & B&W's high-quality anti-reflection coating, which is applied to both sides of the filter, minimizes the possibility of image deterioration due to flare.