The Tiffen 5.65 x 5.65" hard-edge graduated neutral density 0.9 filter helps specifically darken skies and other bright areas of the image. The filter is most dense at the edge and fades towards the centre, with a sharp transition line between the dense and clear areas. Neutral density filters do not affect the colouration of the image and the 0.9 density provides a 3-stop reduction of light entering the lens. This filter is manufactured using ColorCore technology, a process that involves laminating the filter substrate between 2 pieces of optical glass and grinding it flat to a tolerance of 1/10,000th of an inch. This filter measures 5.65 x 5.65" / 143.5 x 143.5 mm. - Hard-edge graduated neutral density 0.9 filter for darkening skies and other bright areas of the image. - Provides a 3-stop reduction of light in selected areas. - Neutral density filters do not affect the overall colouration of the image. Features