The Vivitar 37mm Neutral Density Filter is manufactured from high-quality solid optical materials. The filter is heat-treated to avoid any rare movement or distortion. The ND8 filter allows you to shoot 4 F-stops lower in brightly lit conditions.
This Neutral Density filter reduces intensity of all wavelengths or colors of light equally, giving no changes in hue or color rendition. The purpose of standard photographic neutral density filters is to allow the photographer greater flexibility to change the aperture, exposure time and/or blur of subject in different situations and atmospheric conditions. Instead of reducing the aperture to limit light, the photographer can add a ND filter to limit light and can then set the shutter speed according to the particular motion desired and the aperture set as needed.