1. A rectangular, metal apparatus that resembles a Venetian blind in form and function, generally used as a mechanical dimmer or blackout mechanism on large spotlights. 2. Thin, movable, heat-resistant metal plates that are introduced into a beam such that a portion(s) of the beam is blocked off, i.e., framed, affecting the beam pattern, usually forming a sharp edge in the beam. They are used in various types of luminaires, but extensively in ellipsoidal spotlights, usually 4 (top, bottom, right, and left), and follow spots, usually 2 (top and bottom), always situated internally, and usually at the aperture. Framing shutters generally can be independently adjusted, but those used in follow spots usually move simultaneously with a single control mechanism.