GLOSSARY
- Acting area
- The area of the stage setting within which the actor performs.
- Advance bar
- A spot bar hung within the auditorium, close to the proscenium.
A
- Backlight
- Light coming from behind scenery or actors to sculpt and separate them from their background.
- Bar
- Horizontal metal tube of scaffolding diameter for hanging lights (pipe in America).
- Barndoor
- Four-shutter rotatable device which slides into the front runners of fresnel and PC focus spots to shape the beam and reduce stray scatter light.
- Battens
- Lengths of overhead lighting floods arranged in 3 or 4 circuits for colour mixing.
- Beam angle
- Angle of the cone of light produced by a spotlight.
- Beamlight
- Lensless spotlight with parabolic reflector giving intense parallel beam.
- Board
- Contraction of switchboard or dimmerboard. The central control point for the stage lighting.
- Boom
- Vertical pole, usually of scaffolding diameter, for mounting spotlights.
- Boom arm
- Bracket for fixing spotlights to a boom.
- Build
- An increase in light intensity.
B
- Channel
- A control circuit, identified by number, from the 'board' to a light.
- Channel access
- The method (levers, pushes, keyboard, etc) in a memory system by which individual channels are brought under operator control.
- Check
- Decrease in light intensity.
- Colour call
- A listing of all the colour filters required in each lighting instrument.
- Colour temperature
- A method of measuring (in Kelvin units) the spectral content of 'white' light.
- Control Surface
- Any device such as lever, push, wheel, rocker, mouse, pen, cursor, etc, used as an interface between an operator's fingers and a processing system which activates dimmers or motors controlling lighting instruments.
- Cross-fade
- Lighting change where some of the channels increase in intensity while other channels decrease.
- Cue
- The signal that initiates a change of any kind. Lighting cue is a change involving light intensity alterations.
- Cyclorama
- Plain cloth extending around and above the stage to give a feeling of infinite space. Term is often rather loosely used for any blue skycloth, either straight or with a limited curve at the ends.
C
- Dead
- 1) The plotted height of a piece of suspended scenery or bar of lights.
- 2) Discarded items of scenery.
- Dichroic
- Colour filters which work by reflecting unwanted parts of the spectrum rather than absorbing them in the manner of traditional filters.
- Diffuser
- A filter, often called a frost, which softens a light beam, particularly its edge.
- Dimmer
- Device which controls the amount of electricity passed to a light and therefore the intensity of that light's brightness.
- Directional diffuser
- A filter which not only softens the beam but spreads it along a chosen axis. Also known as a silk.
- Director
- Has the ultimate responsibility for the interpretation of the script through control of the actors and supporting production team.
- Discharge lamps
- Special high powered light sources whose use is normally restricted to follow spots and projection because of difficulties in remote dimming by electrical means. includes C.S.I., C.I.D. and H.M.I lamps.
- Downstage
- The part of the stage nearest to the audience.
D
- Ellipsoidal
- Strictly a type of reflector used in many profile spots but extended in North America to cover all profile spots.
E
- Flood
- Simple instrument giving a fixed spread of light.
- Flys
- Area above the stage into which scenery can be lifted out of sight of the audience.
- Focusing
- Strictly speaking, the adjustment of lights to give a clearly defined image; but usually used to cover the whole process of adjusting the direction and beam of spotlights in which the desired image may be anything but clearly defined.
- FOH
- All instruments which are 'front of house', i.e. on the audience side of the proscenium.
- Follow spot
- Spotlight with which an operator follows actors around the stage.
- Fresnel spot
- Spotlight with soft edges due to fresnel lens which has a stepped moulding on the front and a textured surface on the back.
- Frost
- A diffuser filter used to soften a light beam.
- FUF
- Full-up-finish. An increase to bright light over the last couple of bars of a musical number.
F
- Gate
- The optical centre of a profile spot where the shutters are positioned and where an iris or gobo can be inserted.
- Gauze
- Fabric which becomes transparent or solid under appropriate lighting conditions.
- Gobo
- A mask placed in the gate of a profile spotlight for simple outline projection. Also used, with softened focus, to texture the beam.
- Groundrow
- A low piece of scenery standing on the stage floor. Also lengths of lighting placed on the stage floor.
- Group
- A subdivision, temporary or permanent, of the channels in a control system.
G
- Hook clamp
- A clamp for fixing an instrument to a horizontal bar, usually of scaffolding diameter.
- Houselights
- The decorative lighting in the auditorium.
H
- Instrument
- A stage lighting unit, such as a spotlight or flood. An American term coming into increasing international use.
- Iris
- An adjustable circular diaphragm to alter the gate size in a profile spot. Also the muscle operated diaphragm in the human eye which adjusts the eye's aperture to changing light intensities.
I
- Kilowatt
- see wattage
K
- Ladder
- Framework in the shape of a ladder for hanging side lighting.
- Lamps
- The light source within an instrument, but sometimes used as an alternative to the word instrument.
- Lantern
- A lighting unit designed or adapted for stage use. A traditional word now being overtaken by 'instrument'.
- Linear flood
- A flood using a long thin double-ended halogen lamp, allowing the reflector to be designed for an increased beam spread.
- Load
- The lights controlled by an individual dimmer and limited by the rating of that dimmer.
L
- Master
- A lever or push which overrides (or 'masters') a complete preset, or group within a preset or selected memory.
- Memory
- Lighting control systems where channel intensities for each cue are filed automatically in an electronic store.
- Multiplexing
- Passing control instructions, particularly to dimmers or remotely focusable lights, by sending all information in digital format along a single pair of screened wires.
M
- Pan
- Horizontal (left/right) movement of an instrument.
- Parcan
- The simple instrument which holds a par lamp and therefore does not require any optical system of lenses or reflectors.
- Par Lamp
- A sealed beam lamp with the filament contained within the same glass envelope as an optical system producing a near parallel beam.
- Patching
- A sort of central 'telephone exchange' where channels can be connected to dimmers and/or dimmers connected to socket outlets.
- PC [Plano Convex] Spotlight
- A lens with one flat surface and one curved surface. This 'PC' lens and the fresnel lens are the alternatives normally used in stage spotlights.
- Pipe ends
- Spotlights on the ends of lighting bars, crosslighting to model dancer's bodies.
- Playback
- The part of a memory system where memorised lighting states are recalled to control the light on stage via master levers or pushes.
- Practical
- Light fitting which is not merely decorative but is wired to light up.
- Preset
- Anything which is positioned in advance of its being required --such as props placed on the stage before the performance. A control system where each channel has more than one lever to allow intensity levels to be set (i.e. preset) in advance of a cue.
- Profile Spot
- A spotlight which projects the outline (i.e. the profile) of any chosen shape and with any desired degree of hardness/softness.
- Profiled Cue
- Lighting change where the rates of increasing and decreasing intensities accelerate or decelerate during the progress of the change.
P
- Rating
- The maximum and minimum power in kilowatts that can be controlled by a circuit or dimmer channel.
- Record
- Plotting a cue state by filing it in the electronic data storage of a memory board.
- Resistance dimmer
- An older mechanical form of dimmer which reduces the flow of electricity to a light by progressively converting the surplus into heat.
- Rigger's control
- A remote portable hand-held control unit which allows channels or groups to be switched from the stage for focusing when the control room is unmanned.
R
- Scatter
- Low intensity light cast outside the main beam of an instrument.
- Scrollers
- Colour changer where a roll of filters are taped together and positioned by a very fast motor activated by digital signals from a control system which includes a memory facility.
- Shin Busters
- Low level lights at stage floor level, used mainly for dance.
- Sightlines
- Lines drawn on plan and section to indicate limits of audience vision from extreme seats, including side seats, front and back rows, and seats in galleries.
- Silks
- Diffusion filters which stretch the light in a chosen direction.
- Spigot
- An adapter screwed to the hanging bolt of an instrument to enable it to be mounted on a floor stand.
- Spill
- Stray or scatter light outside the main beam.
- Spotlight
- An instrument giving control of the angle of the emerging light beam and therefore of the size of area lit.
- Strobe
- Device giving a fast series of very short light flashes under which action appears to be frozen.
S
- Theatre-in-the-Round
- A form of staging where the audience totally encircle the acting area.
- Throw
- Distance between a light and the actor or object being lit.
- Thrust
- Form of stage which projects into the auditorium so that the audience are seated on at least two sides.
- Tilt
- Vertical (up/down) movement of an instrument.
- Tungsten lamps
- Older type of lamps (the stage types are high wattage versions of standard domestic lamps) whose tungsten filaments gradually lose the brightness of their light output.
- Tungsten halogen lamps
- Newer lamps (now virtually standard in professional theatre) which maintain their initial brightness of light output throughout life.
T
- Upstage
- The part of the stage furthest from the audience.
- UV
- Ultra violet light (from which harmful radiation have been filtered out) used to light specially treated materials which fluoresce in an otherwise blackened stage.
U
- Variable bean profile
- Profile spotlight using a type of zoom (q.v.) arrangement where the differential movement of two lens allows wide variations in both beam size and quality.
V
- Wattage
- The power of consumption of a lamp, or the maximum available power from a dimmer. A kilowatt is 1,000 watts.
- Ways
- The number of channels in a control system.
W
- Zoom
- A differential movement of two lenses in an optical system. In a simple zoom, the lenses are moved independently, but in more complex forms a single movement alters the size of the beam while the image remains in constant focus. Used in advanced profile spots and scene projectors.
Z
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