LAN : Local Area Network. A network of computers connected via cables or a wireless system.
LANC: A connection developed by Sony, used to link remote-control units, edit decks, etc.
Lavalier Microphone (AKA lav, lapel or lap microphones.) A very small condenser mic designed to pick up speech from a single person. More Info: Lav Mics, Condenser Mics
Lens: A transparent structure made of glass or other material, with at least one curved surface, which causes the light rays passing through it to converge or diverge in a controlled fashion. More info: Lenses
Letterbox Format: In video and television, the practice of placing black bars at the top and bottom of the frame, in order to simulate a wide-screen format (as if the viewer were looking through the slot in a letterbox). More info: Letterbox format, Aspect ratios
Light: That section of the electromagnetic spectrum which is visible, ie. perceptable to the human eye. Specifically, white light contains the wavelengths from 400nm (nanometres) to 700nm. Light travels through a vacuum at approximately 300,000 km (186,000 miles) per second. More info: Lighting tutorials
Lighting, Three-Point: A standard lighting technique using three lights: The key, fill and back lights. More Info: 3 point lighting
Limiter: A device which limits the level of a signal to a specified threshold.More info: Audio Limiters
Loudspeaker: A transducer which converts electrical signals into sound waves.
Lower Third: The lower portion of a video frame which contains graphical information such as station ID, name/title key, etc. More Info: Lower Thirds