A Barndoor is a lighting accessory that is used to control the direction and shape of light produced by a lighting fixture. It is typically made up of four adjustable metal flaps or doors that are attached to the front of the light. These flaps can be adjusted to block or shape the light in specific ways.
Barndoors are commonly used in film and photography to control the spread and direction of light, and to create shadows and other lighting effects. For example, a cinematographer might use barndoors to create a narrow beam of light that is directed at a specific area or subject, or to create a pool of light that highlights a particular part of the scene.
Barndoors are often used in conjunction with other lighting accessories, such as diffusers, gels, and reflectors, to achieve a particular lighting effect. They are available in a range of sizes and shapes to fit different types of lighting fixtures, and can be adjusted to create different lighting patterns and effects.