A nonspeaking role. See extra.

An initial rehearsal in which the technical personnel and the actors walk slowly through a shot to identify potential problems.

Also called walkie-T. Colloquial term for a pair of portable, battery-operated transmitting-receiving sets used in wireless (talk) communication.

Space left ahead of a moving subject in a panning shot, to aid composition and screen direction.

A light fixture with a flat surface that attaches to a wall in order to hold a light.

Background speech (murmuring and muttering and buried conversations) in which individual words cannot be clearly distinguished. Since extras usually mouth their conversations silently, specialists in this work—“Walla groups”—can be found to provide a blanket of background voices during postproduction.

A background sound that involves the recording of people’s voices so that the actual words they are saying cannot be understood.

See costume.

Introductions and preparation (getting into mood) of a live audience in the broadcast studio prior to transmission.

See lineup time.

Washing; the bath in a film processing machine that removes, washes off the remaining chemicals from the film after developing and fixing.

Water marks, spots, left on the finished film surface after processing and draying.

A unit of electrical power that equals the power expended when l amp of current flows through l ohm of resistance.

Instrument for the direct measurement in watts of electrical power.

Electrical power measured in watts.

See electromagnetic waves.

A conducting tube for microwave signals.

An instrument for measuring wavelength.

The propagation of the wave forward at a distance equal to its wavelength.

A visual representation of an audio or video signal.