B+W gray filter ND 0.9 MRC nano master 72 mm. This B+W gray filter reduces light by three f-stops. This gray filter is especially useful for video when an appropriate aperture value cannot be set in high brightness or when a shallow depth of field is desired. At this filter strength, a clear flow effect can already be seen with water. The B+W 803 gray filter ND 0.9 is also ideal for shots with a wipe effect.