The bw 67mm 1864x 106 neutral density 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 flowing water is rendered as 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 colour photographs if this effect is und