Description
A graduated Filter neutral-density filter, also known as a graduated ND filter, split neutral-density filter, or just a graduated filter, is an optical filter that has a variable light transmission. Typically half of the filter is of neutral density which transitions, either abruptly or gradually, into the other half which is clear. It is used to bring an overly-bright part of a scene into thedynamic range of film or sensor. For example, it can be used to darken a bright sky so that both the sky and subject can be properly exposed.