The B+W Neutral Density+6 F-PRO Digital Filter reduces the light by six f-stops. With this filter & without changing the f-stop, a shutter speed of 1/60 s is changed to a full second, thus requiring the use of a tripod. Moving water is rendered as blurred & flowing in the photo, & 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 undesirable, a B+W UV-/IR-Blocking Filter 486 in front of the neutral density filter (not behind it) remedies that situation. The filter factor is 64x.