This MRC HD True-Color Hard-Stop ND2-ND400 VND Filter from Neewer fits 49mm lenses and features a built-in rotating aluminum ring with hard stops that controls neutral density ranging from ND2 to ND400 with approximately 1 to 8.6 stops of light reduction. This longer exposure allows the shutter to remain open long enough to record the same amount of light, but will also create movement within the shot. The built-in rotating polarization eliminates having to buy and carry around individual neutral density filters. It fits a separately available 52mm lens cap.
This VND filter can be used to create special effects, including capturing the blur of rippling water in a waterfall or the swirling effect of city traffic. Since it allows the use of slower shutter speeds in bright light, it becomes possible to create effects that would normally not be possible without the filter.
NOTE: The mechanism of variable ND filters is based on the principle of polarization. Using the maximum aperture may result in a black X due to the VND filter's interaction with certain lenses and focal lengths.