Glossary
802.11 A set of standards for wireless local area network (WLAN) computer communication.
Accent A design technique in concert lighting that concentrates the illumination at strategic points on the stage to punctuate the music with heavy color or intensity.
ACL (aircraft landing light) A PAR-64 design with a very narrow beam pattern which operates at 12 volts and was originated for jet aircraft then adapted for rock & roll.
Air graphics Another word for air light.
Air light The use of light beams to create patterns and design elements; the patterns may or may not be focused on the artist.
Aircraft cable (wire rope) Cable made of stainless steel stranded wire of high tensile strength and used for hanging trusses, sound, and scenic elements where house pipes are not available; theatrical rigging usually uses 3/8- or 1/2-inch-diameterc able.
ANSI American National Standards Institute. Art-Net A way of sending DMX information over information processing (IP) networks. It is Artistic Licence's proprietary name for their Ethernet cable, which can carry more information than DMX cable.
Backlight Illumination of a subject from the rear to produce a highlight along its edge.
Barco A global technology company that designs and develops visualization products for a variety of professional markets.
Box truss Structure built of aluminum, steel, or chromemoly, designed as a portable support of lighting luminaires but sometimes used for support of drapery, scenery, or sound equipment.
Bridle In rigging, a system for utilizing more than one hanging point to distribute the load.
CAT5 An eight-tined cable similar to the four-tined phone cable that carries information to the Ethernet.
Chain hoist Electrically operated lifting device usually utilizing chain; often referred to as chain climber.
Chase Timed, programmed sequence of dimming channels.
Color temperature Color quality of light (measured in degrees Kelvin) relating its spectral distribution to that of a standard “black-body” radiator.
Contract rider Supplementary agreement between the promoter and artist, having its basis in the original contract and incorporated by reference to the original contract. Normally, it contains specific physical requirements of the artist's current show such as stage size, power, dressing room needs, food, etc.
Contrast range Brightness ratio between the lightest and darkest tones in a scene.
Cyclorama Vertical surface used to form a background. Generally, it is monochromatic and is constructed of either hardwood with a fabric covering or heavy cloth, often muslin, stretched vertically and horizontally to create a smooth surface.
Depth of field The zone or range that still shows clarity closer to and farther from a lens at sharpest focus. The zone increases as the lens aperture is reduced (often accomplished by increasing light level) or the lens angle is widened.
Desk British term for lighting control console.
DMX Digital Multiplexing.
Digital light Luminaire that uses digital projection techniques to modify the beam parameters, primarily shape, intensity, and color and video content such as live images and recorded media.
Ediophor Commercial-grade, large-screen video projector made in Switzerland that utilizes an RGB color system to produce a video image electronically by etching the images into an oil film that modulates a high-intensity xenon light source.
End-stage Placement of a portable stage in an open, flat floor building centered on the short end to give maximum seating capacity.
Equipment manager Acceptable professional term for the person who sets up and maintains the band equipment.
Ethernet Standard communications protocol embedded in software and hardware devices, intended for building a local area network (LAN); Ethernet cable carries far more information than DMX cable.
Exposure The selective control of reproduced tonal values within a system's limits. Overexposure results when reflected light exceeds the camera's limits; underexposure results when a surface is insufficiently bright to be clearly discerned in the picture.
Fill light The supplementary illumination used to reduce shadow or contrast range.
Flash button On a lighting console, a momentary contact switch that allows a control channel to bypass the fader and instantly bring the circuit to 100% output. Normally found on consoles designed for rock & roll applications.
Follow spot High-power, narrow-beam light suited for long throws (typically 100 to 300 feet), generally with an iris, shutters, and color changer; it is designed for hand operation to follow the movements of performers.
Found space Any space used for theatre, concerts, or television productions not specifically designed as a performance area.
f-Stop A measure of the light-transmissiveability of a camera or projection lens.
Gobo A pattern or breakup placed in front of a hard edged light designed to cast a specific design or modeling onto a surface.
Grand tour A tour taken by a star, usually with only a piano, to perform excerpts of famous opera and classical works.
Groupies People, often girls, who are so devoted to a popular recording artist that they collect memorabilia, join fan clubs, and go out of their way to be everywhere the artistis.
Hanging point The point on the truss from which the attachments are made for rigging.
HD High-definition.
High-density dimming The use of advanced engineering and microprocessors to miniaturize the electronic dimmer.
HMI Mercury (Hg) medium short-arc iodide lamp (mercury/argon additives) in tubular, sometimes double-ended form at 5600 Kelvin or higher. In entertainment this is preferred definition. Manufacturers technical term is Hydrargyrum Medium Arc Iodide.
Hod A number of individually jacketed cables, usually three #12 wires, taped together for easy transport and layout on a lighting pipe.
HTI Metal halide short-arc lamp at 5600 Kelvin. Color temperatures are available up to 7200 Kelvin (daylight).
IATSE International Alliance of Theatrical Stage Employees, the international bargaining unit for stagehands, including property masters, audio technicians, carpenters, riggers, electricians, wardrobe mistresses, and other backstage employees.
Iso An abbreviation of the word isolated; in television it denotes the switching of a camera onto a tape reel other than the master tape.
Kelvin temperature The unit of temperature used to designate the color temperature of a visible light source.
Key light Motivating source of illumination that establishes the character and mood of the picture.
Key word Method of calling cues that does not rely on visual or mechanical signaling devices; an expression such as “go or out” prompts someone to react in a planned manner.
Keystone correction Compensating for off-angle projection of the image on a surface.
LAN Local area network.
Layering The use of color to create depth and separation by using different shades or saturations of a single color.
Letter of agreement A legal agreement generally written in plain language and in business-letter form rather than legal form.
Light show Mixture of theatrical lighting, projections, film, and blacklight images used to create an environment for the audience (popular in the 1960s).
Looks Planned patterns of light and often color combinations that are programmed and used one or more times in a concert.
Lumen per watt The number of lumens produced by a light source for each watt of electrical power supplied to the filament.
Lumens A unit of (light) flux.
Luminance The true measured brightness of a surface.
Luminaire The modern term for all theatrically designed lighting instruments.
Matrix or pin matrix A device used to group channels to one or more master controllers, often employing a small pin or patch placed on the console.
Media server Computer dedicated to the task of playing and organizing video clips, stills, or 3D images during a performance.
MMA MIDI Manufacturers Association.
Modeling Three-dimensional rendering of lighting system and components of the stage set relative to stage dimension and height exactly as they would be in real time.
MOR Middle of the road, designating music that is marketed between easy listening and rock & roll, such as Barry Manilow, Air Supply, and John Denver.
Multicable More than one complete electrical circuit housed in the same flexible protective jacketing.
Offline editing Preliminary editing of videotapes, using copies of the original tapes; usually performed on a low cost 1/2-inch editing system that allows the director to try various edits before the final edit without expensive edit bay and editor costs (often called a work tape).
Online editing Final editing of videotapes using the original master tapes to produce a finished program.
Package dimming The grouping of typically 6 or 12 dimmers in a single, integrated enclosure, often used for portable work.
PAR-64 Parabolic aluminumized reflector luminaire used with a quartz lamp sealed behind one of a group of lens configurations. The “64” designates the diameter of the lens in eighths of an inch.
Patching Interconnecting dimmer output to loads via a patch panel, a system that usually uses a plug and jack on the line side of the load only.
Per diem Daily allowance paid to the crew and cast by their employer while they are away from home; it is used to cover nonreimbursed expenses such as food and laundry.
Pickup point The point of attachment to the building's load-bearing structure used for rigging.
Pigtails Short 3- to 5-foot cables, usually #2/0 or #4/0 welding cable, used to connect to the house power panel.
Pink contract An agreement issued by IATSE to qualified members who want to travel outside of their local jurisdiction.
Pin matrix SeeMatrix.
Pixel mapping Video scaling technique used in display devices. A monitor that has been set to 1:1 pixel mapping will try to display an input source without scaling it, such that each pixel received is mapped to a single pixel on the monitor. This will often result in a black border around the video unless the input resolution is higher or the same as the monitor's native resolution.
Port, Ethernet Most common connection to LAN networks for high-speed computers. Looks like a slightly larger phone jack.
Prep The time devoted to organizing and packaging materials such as lighting or sound prior to the rehearsal or tour, usually in a location other than the first venue.
Programming The real-time mixing of multiple video camera shots or taped feeds onto one master tape or into a live line transmission.
Proscenium An arch placed so as to separate the audience from the acting or performance space, often called a “picturefr ame.”
Psycho visual Relating to the psychological use of color to effect emotional response in the viewer.
Punch light A luminaire with a highly concentrated beam that allows long throws.
RAID (redundant array of independent disks) A disk subsystem that is used to increase performance or provide fault tolerance or both. RAID uses two or more ordinary hard disks and a RAID disk controller. RAID has also been implemented via software only.
Ray light Reflector with a separate 120-volt lamp, usually of 600 watts, which fits into a PAR-64 housing. This unit creates a very narrow beam of light, the same as an ACL but without the problem of matching 12-volt to 120-volt dimming.
RGBHV Red, green, blue , high voltage.
Rigging The process of installing lines or motors to support trusses, scenery, etc., in their required positions.
RJ45 Another name for Ethernet connector.
RMS Root mean square, a method of averaging a sine wave to arrive at a mean average.
Road company The authorized production of a play or musical that is produced in one city and then performed in multiple cities for limited engagements around the country.
Roadies An early term used for people who traveled with popular bands and took care of the musical equipment.
Saturation The purity of a color; the extent to which a color has been diluted.
SCR (silicon-controlled rectifier) dimmer Solid-state electronic device used to control lamp brightness by cutting off part of the cycle or the alternating current supply in a specific type of dimmer.
Scrim A gauze-like curtain that, when illuminated from the front, appears opaque; if light is brought up from behind the scrim, it becomes transparent.
SD Standard definition (standard for digital video disk recorders).
Set The order of songs to be performed, generally used for musical performances where no dialog or scripted words are recited.
Sidelight The source used to rim faces and model profile shots, often at or near head height.
Soft patch An electronic means of assigning dimmers to control channels without physically wiring jumpers on a terminal board or patch panel.
Span set Circle made of nylon web strands encased in a nylon covering that is wrapped around areas of load-bearing structures to prevent chafing.
TCP/IP Transmission Control Protocol/ Internet Protocol.
Theatrical smoke Smoke created either through a chemical reaction or combustion (often caused by heating an oil-based liquid until it vaporizes).
Torm Slang word for “tormentors,” which are the side curtains that hang next to the proscenium opening; these curtains can be adjusted to alter the width of the performance area.
Trade usage Custom or widely used practice common to a business, usually unwritten but believed to be generally understood.
Truss Metal structure designed to support a horizontal load over an extended span. In theatre and concert work, it is the term applied to the structure that normally supports the lighting over a 40- to 60-foot clear span.
Tungsten-halogen lamp (quartz) Type of lamp design achieving an almost constant output and color temperature with a higher lumen output through the working life of the lamp. The halogen vapor (or bromine or iodine) facilitates a chemical recycling action, preventing the blackening of the bulb wall with filament particles.
Turnaround In music, a point in the tune when the melody is broken up by another musical idea, after which the original melody is repeated.
United Scenic Artists (USA) National trade union that represents theatrical designers such as set designers, lighting directors, scenic artists, and model makers.
UDP/IP User Data gram Protocol/Internet Protocol.
Universe One DMX grouping of 512 channels.
Venue The location of a gathering; often used in legal contracts to designate the location of the concert.
VGA Videographics array.
Violent failure The term most often used to describe a lamp exploding.
Wire rope Similar to aircraft cable but generally with less tensile strength.
Warping Similar to the Keystone principle, except the image can adapt and scale to the curvatures.
Xenon A compact source discharge lamp containing xenon gas in a pressurized lamp housing.
Yellow card A term used by IATSE to designate shows in which all the technicians are members of the union working under a signed agreement for wages and working conditions, sanctioned by the international office.