The Schneider Optics Day for Night Filter 6.6 x 6.6 is used by cinematographers to simulate nighttime moonlit scenes, while actually shooting during daylight. Shooting during daylight can dramatically reduce the need for lighting, therefore lower production costs, and opens up more shooting schedule options.
This filter combines a slight aquamarine tint with neutral density for a realistic illusion of night time. 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.