Schneider Cine ND 1.8 4x5.65

Cine ND — neutral density filter, takes light away so you can lengthen the exposure or open the aperture.

A neutral density filter takes light away without touching the colours. In daylight it lets you shoot wide open with a blurred background, film at 1/50 s by the cine rule, or lengthen the exposure until water melts into mist and people vanish from the frame.

The 4″ × 5.65″ size is the cinema standard, so the filter fits common matte boxes and filter trays. It is not screwed onto the lens but slid in front of it, which allows several filters to be stacked and swapped without touching the lens.