Neutral Density (or ND) filters produce a grey neutral effect and are used to reduce light entering the camera, enabling control over exposure and depth of field without affecting color or contrast. ND's are made in different densities according to the level of light reduction from 1 stop to 4 stops of light and are made from the highest quality 1.5mm optical resin.
Neutral Density (ND) filters are the essential filters for digital photography and cinematography
ND filters reduce the amount of light entering the camera
Allow the photographer to create the following effects:
Ethereal waterfalls and streams
Flat water effect in oceans and lakes
Streaky clouds
Motion blur in sports
Long exposures to remove people from public areas
Shallow depth of field using fast lenses wide-open