Neutral Density (ND) Filters 

ND stands for Neutral Density. In photography and optics, a neutral density filter or ND filter is a filter that reduces or modifies intensity of all wavelengths or colors of light equally, giving no changes in hue of color rendition. The purpose of a standard photographic neutral density filter is to allow the photographer greater flexibility to change the aperture, exposure time and/or motion blur of subject in different situations and atmospheric conditions.

Technical Parameters

Detail figures of Variable ND

variable ND filter can change different ND from 1 to 8 stop by rotating the filter ring. One variable ND equals to several single piece of ND filters which photographers can avoid bringing and changing different ND filters from time to time.