This filter is used by cinematographers to simulate nighttime moonlit scenes, while actually shooting during daylight. Shooting during daylight can dramatically reduce the need for lighting and therefore lower production costs. This filter combines a slight aquamarine tint with neutral density for more realistic night time illusion. It reduces exposure by 4 stops, although exposure compensation is typically only 2 stops, resulting in underexposure that enhances the illusion. When doing Day-for-Night shots it is essential to control sky exposures, often by leaving the sky out of the shot. If the sky must be in the shot, ND Grad filters and Polarizing filters can be used to darken the sky.