The Hoya ND 500 reduces light by the equivalent of 9 stops. ABOUT ND FILTERS Neutral density (ND) filters are the most sought-after and important photographic filter types for several reasons. For photographers, ND filters mean precise control of the amount of light passing through the lens to allow greater creative control of exposure. For video content creators, ND filters are very helpful in adjusting shutter speeds to match frame rates while maintaining the depth of field of the footage. Thanks to the leading ACCU-ND technology, the image does not experience the negative effects of color shifts that can occur due to inferior materials, poor quality control during manufacturing, or problems with leakage from the infrared portion of the light spectrum. HOYA's exclusive ACCU-ND technology achieves uniform reduction of light in the visible and IR spectrums. As a result, the photographer does not have to worry about color shift problems when using HOYA ND filters under different shooting conditions.