The bw neutral density6 f pro digital filter reduces the light by six f stops with this filter and without changing the f stop a shutter speed of 160 s is changed to a full second thus requiring the use of a tripod moving water is rendered as blurred and flowing in the photo and people moving in streets are dissolved in unsharpness or become invisible because of its higher transmission in the red beyond 660 nm this filter brings a slightly warm tone to color photographs if this effect