This B+W Nd filter, which reduces light entering the camera by six f-stops, already qualifies as an extreme filter. With this filter, and without changing the aperture (and Dof), an exposure time of 1/60 s becomes a full second. Running water is rendered hazy and soft. A tripod is necessary in any case.The excellent finely ground and polished special glass is used as the basis for the new Nd filter glasses. This guarantees the necessary optical quality and also does not have any adverse effect on a correspondingly high-quality lens.With the thin-film technology developed here, not only the pure Nd filter effect comes into play, but a coating combination optimizes the Nd filter. In addition to the filter effect, the coating combination contains a multi-layer anti-reflective component with 7 layers per filter side to prevent annoying reflections. An outer layer with the usual dirt- and water-repellent properties is applied as the final layer.