Neutral Density filters appear grey and reduce the amount of light reaching the film/light sensor. They have no effect on color balance. Determining which neutral density filter yields ideal results for any given lighting situation takes knowledge, experience and a collection of such filters. Speaking generally, the 2-stop value (ND 0.6) effectively compensates average situations.
ND filters have four main uses:
- To enable slow shutter speeds to be used, especially with high speed films, to record movement in subjects such as waterfalls, clouds, or cars.
- To decrease depth of field by allowing wider apertures to be used, which helps separate subjects from their background.
- To decrease the effective ISO of high speed film (above ISO 400) and allow it to be used outdoors in bright situations.
- To allow cine and video cameras(which have fixed shutter speeds) to film subjects such as snow, sand or other bright scenes which could cause overexposure.
Note: Neutral Density filters are available in grades 1,2,3,4,5,6,7 and 8 stops to suit individual needs.
More information on Marumi filters: (Link to Marumi International Website)