This is a Graduated Neutral Density Filter used for Cinematography. 50% of the filter is clear and 50% has a Neutral Density of 0.9 (3 stop). The transition from clear to ND is done with a HARD EDGE (HE) transition line. Hard Edge grads lines are used with long focal length lenses where the hard transition line is softened by the long focal length lens. Graduated Neutral Density filters are used to balance exposure within a scene. One very common use is to balance the exposure of sky and earth in a landscape, avoiding overexposed blank white skies.
The Schneider Group specializes in developing and producing high-Performance lenses for film and photo, cinema projection lenses, as well as industrial optics and precision mechanics. 1913 founded in Bad Kreuznach, Germany, as a mechanical shop for optical lenses, Jos. Schneider Optische Werke GmbH is today a worldwide market leader in high-quality lenses and precision engineering.