The Hoya ND 200 reduces light by the equivalent of 7 2/3 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 that passes through the lens to allow greater creative control of exposure. HOYA offers both photographers and filmmakers its own exclusive and broad range of ND filters embedded in the PROND series. PROND filters use HOYA's clear optical glass mounted in a lightweight, precision-machined aluminum frame. The frame features a front filter thread so you can attach additional filters or a lens cap. 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.