Barndoors

Barndoors are metal flaps — typically two or four of them — hinged to the front of a professional light fixture. They work exactly like the doors on a barn: open them wide and light spills freely in all directions; close them partially or fully and the beam is shaped into a precise rectangle or strip. This gives cinematographers and gaffers direct mechanical control over where a light source hits and, more importantly, where it doesn't. Without barndoors, lights tend to spill onto backgrounds, other subjects, or the camera lens itself.

The most common use of barndoors is controlling spill — the unwanted spread of light onto the background or into the camera. If a key light meant to illuminate a presenter is also lighting the backdrop unevenly, partially closing the bottom barndoor can cut that spill without changing the exposure on the subject. They're also used to create dramatic split-lighting effects, to keep practical lights from washing out the frame, and to prevent lens flare caused by light hitting the camera directly.

Barndoors are a fixture (no pun intended) in both film and broadcast lighting kits, typically made of heat-resistant black steel and available in two-leaf or four-leaf configurations. They're most effective on fresnel-type lights, which produce a hard, focused beam. Softboxes and other diffusion modifiers don't use barndoors, since the light source is already diffused and spread. In a pinch, black wrap (black aluminum foil) can substitute for barndoors on smaller fixtures, though it's less precise and doesn't hold a position as reliably.