Illumination used to make something stand out.
It may be done with intensity and/or color.
A luminaire that provides such
illumination.
Amp
an abridged version of Ampere.
Amperage (A)
The measure of electrical current in
amperes.
Ampere(A)
A unit of measurement for Electrical Current.
AMX
Abbreviation for Analog Multiplex.
Analog Multiplex (AMX)
A system that simultaneously transmits more
than one analog signal.
Analog Signal
A continuous communication signal where the amplitude
or frequency of the voltage and/or current takes any value within
a range of values.
ANSI
Abbreviation for American National Standards
Institute.
ANSI Code
A three letter system that has been devised to
describe lamps of different manufacture but the same
application. The letters have no relationship to lamp
description, but the same letters always designate the
same type of lamp. Some of the application parameters
they define are wattage, base type, envelope size, and
light center length.
Arc
The light caused by an electrical discharge between
two electrodes in a gas such as xenon, argon, or air.
The first usable arc as a practical light source was
developed in 1809 by Sir Humphrey Davy.
Automated Light
A luminaire that is robotic, i.e., certain
functions such as panning, tilting, focusing, dimming,
beam shaping and coloring, etc., are motorized and
remotely operated from a control console.
Axial
A term used to describe a luminaire whose lamp is
mounted on the same axis as its optical system.
Illumination on a subject from behind, causing a
separation of the subject from the background, often
creating a fringe of light around the subject.
A luminaire that provides such
illumination.
Ballast
An electrical apparatus that limits the electrical
current in a particular circuit, usually a circuit
containing an arc source.
Bank
A group of luminaires.
A group of dimmers or dimmer modules.
A group of sliders or channels on a control
console.
Bare Ends
Leads without a connector installed.
Bare Leads
See the definition for Bare Ends.
Barn Doors
An apparatus with adjustable flaps, usually 2, 4 or
8, that attaches to the front of a luminaire. It is
used to block or shape the beam.
Barrel
An abridged version of Lens barrel.
A male turn-around, generally used for the
connection of control cables.
Base
The bottom of a stand used for mounting
luminaires.
The part of a lamp to which the electrical
connections are made, i.e., the part with the contacts.
It is often the mechanical support and/or heat sink for
the lamp.
The flat, bottom support for some
luminaires.
Batten
A horizontal pipe on which luminaires, scenery,
curtains, and some distribution equipment are
hung.
Batten Strip
a connector strip hung from a batten.
Beam
Generally, the conoid, or in some cases, the
pyramoid of light emanating from a luminaire.
In Photometry, the circular area of the base of
a cone-shaped beam where the intensity is at least 50%
of the maximum intensity. The maximum intensity is
ideally located at the center of the base. It should be
noted that some luminaires, such as ellipsoidal
spotlights and follow spots, can be adjusted or
designed such that the light emanating from them does
not include the entire beam, i.e., the edge of the beam
is greater than 50% of its center.
Beam Angle
The angle of the vertex of a cone shaped beam where
the perimeter of the base is defined by where the
intensity is 50% of the maximum intensity.
Beam Pattern
The complete shape of the beam, as defined in the
general sense. It includes any realistic or abstract
patterns introduced into the beam as well as any
apparatus that alters the contour of the beam.
Beam Spread
See the definition for Field Angle.
Black light
A luminaire with a beam whose wavelengths are too
short to be visible, i.e., 320 to 380 nm. These
ultraviolet wavelengths excite fluorescent materials,
paints, etc., in theatrical applications.
Blackout
To remove or the removal of all or almost all light
on the performing area, usually done rapidly.
Bleed Through
The effect created by adjusting the intensity of
the illumination directly on a theatrical scrim
inversely with the intensity of the illumination behind
it. This causes the scrim to go through a phase of
changing transmission.
Boom Base
A heavy, steel or iron base used in the theater
industry to support a boom.
Borderlight
A striplight often used at some border on a stage
or over a stage. This could be an area between two
curtains or at the edge of the stage floor, cyclorama,
runway, etc.
Breakout
A special power cord that has one male or female
multiconnector electrically connected to a plurality of
female or male connectors, respectively, via separate
cables or sets of sleeved wires. In most cases, each
contact of the multiconnector is electrically connected
to only one of all of the collective contacts on the
other connectors.
Bubble Machine
A machine that emits a continuous stream of
soap-based bubbles.
Bump
To change the intensity of a luminaire or group of
luminaires instantaneously, usually for a short
duration of time, often to the beat of music as if to
create a pulsing effect.
Burnout
The melting of a lamp filament.
A term used to describe certain roadies.
Bus
A conductor comprising a thick metal strip, usually
copper, brass, or aluminum, to which other devices,
such as fuses and circuit breakers, as well as a means
to make electrical connections, may be attached. Buses
are often used in power distribution equipment that
handle large amounts of electrical current, e.g.,
panelboards and switchboards.
See definition for Pipe clamp. In the film
and video industries, a "C" shaped clamp that attaches
onto a pipe and locks with the aid of a bolt, that when
tightened, presses like a vice onto the pipe. It also
has a stud or studs for the attachment of luminaire,
grip equipment, etc.
C-Stand
see Century Stand
Cable
A rope of wire used to transmit electricity or
data.
To run, hook up, and/or interconnect electrical
cables and the items to which the cables are
connected.
A strong, flexible, wire rope made of steel,
used to support pipes, battens, truss, etc., from an
overhead structure.
Cable Bundle
A group of electric cables attached at various
points by tape, rope, etc.
Cable Cradle
A metal sling used to support heavy stage cable as
it hangs from a batten, while simultaneously preventing
the cable from entering horizontal sight lines from the
house to the stage. It can also take strain away from
the point where the cable exits a piece of distribution
equipment.
Cable Drop
An overhead electric cable or group of electric
cables that extends downward for the connection of
luminaires or other electrical apparatuses. The
cable(s) may be connected to some type of overhead
support, or directly to a piece of distribution
equipment.
Cable Hook
A hook that attaches to a stand used to hold excess
coils of electric cable, often found on follow spot
stands.
Cable Mount
A term used to describe a connector designed to be
electrically attached to the end of a cable.
Cam-lok
A commonly used type of insulated, locking, single
conductor cable connector manufactured by Crouse-Hinds
Inc. The name Cam-lok is trademarked.
Candle (cd)
The unit of Luminous Intensity of a light
source.
Candlepower (cp)
A term often used in place of Luminous
Intensity.
Cap
The removable or hinged, rear cover of some
luminaires that contains the lamp socket, lamp, and
power cord.
See definition for Base.
Carbon Arc
An arc source in which the arc is formed in air
between a pair of carbon electrodes.
Card
In general, a circuit board.
See Dimmer Card or Control Card.
Catwalk
A raised, overhead platform used in film industry
studios, used for mounting and accessing luminaires and
other types of production equipment. Located around the
perimeter of the studio floor, they are often painted
green and are always provided with handrails.
Century Stand
A grip stand manufactured by Matthews Studio
Equipment Corp. The name Century Stand is
trademarked.
Channel (ch)
An individual control output on a control console,
accessed and regulated by a slider, switch, or button,
or in, some cases, accessed by a discretely assigned
address and regulated by a data input apparatus.
Chief Electrician
Master Electrician or Gaffer.
Chief Lighting Technician
Master Electrician or Gaffer.
Circuit (ckt)
A complete electrical path leading from an
electrical supply through conductors and perhaps
dimmers, distribution equipment, electrical devices,
electronic items, etc. to the load and returning to the
source. The load is quite often a lamp.
Circuit board
A plastic or fibrous card that contains electronic
components and the wiring and/or tracers that
interconnect them.
Circuit Breaker
An electrical device designed to open and close a
circuit by non-automatic means and to open the circuit
automatically on a predetermined over current without
damage to itself.
Circuit Breaker Panel
A panelboard that houses circuit breakers.
Cold Mirror
A mirror that transmits heat, i.e., infrared
radiation, but reflects light.
Cold Start
A term used to describe the ignition of a cold arc
lamp, i.e., a lamp that has not been electrified for a
relatively long period of time.
Color
(see color medium) To place color media in front of
a luminaire to alter the color of the beam.
Color Balance
An arrangement of hue, chroma, and value within a
design that produces a sense of equilibrium, i.e., no
colored area commands attention to the detriment of the
entire arrangement.
Color Changer
(also color scroller, color wheel) An apparatus
that attaches to a luminaire and allows one to manually
introduce one or more color frames into the beam. Color
changers are most often found on follow spots.
Color Correction
Adjusting the color temperatures of various
luminaires so that they are all the same, or to make
them match existing light sources, e. g., sunlight or
fluorescent light. This is usually accomplished by
utilizing color media, but adjusting the input voltage
levels is a method sometimes used for some
luminaires.
Color Filter
see color medium.
Color Frame
An apparatus used to hold color media or other
types of filters. It can be of various shapes and
sizes, and may comprise one or more pieces.
Color Medium
Any colored transparent material that con be placed
in front of a beam to color the light. They can be of
the absorption or reflection type.
Color Rendering Index (CRI)
A single number approximate evaluation of the
effect of a light source on the visual appearance of a
colored surface. The number falls on a scale from below
0 to 100, with daylight at 100. Objects and people
viewed under lamps with a high CRI generally appear
more true to life.
Color Scroller
An electronic, motorized apparatus that mounts on
the front of a luminaire, and allows for the automatic
placement of one of a number of gels to be placed in
front of the beam.
Color Temperature
The temperature, in degrees Kelvin, of a black-body
that generates light with the closest visual color
match to the source being specified, i.e., a measure of
the color appearance of light, not the actual
temperature of the light.
Color Wheel
An apparatus holding several different gels that
can be rotated by hand or motor such that any one gel
can be placed in front of a luminaire with relative
ease.
Colorine
lamp dip
Complementary Colors
Two colors of light that combine to make white
light in the additive color mixing system. For red,
green, and blue, the complementary colors are cyan,
magenta, and yellow, respectively.
Complementary Tints
Two colors in the additive color mixing system that
combine to make nearly white light.
Computer Board
memory board
Concave
A term used to describe a lens side that is
inwardly and usually spherically curved.
Conduct
To carry electrical current.
Conductor
Generally, anything that will carry electrical
current, but usually refers to an insulated wire.
Cone
see Snoot.
Cone Light
A soft light luminaire that uses a single ended
lamp and a cone shaped reflector.
Connector
Specifically, the name for a family of
electrical wiring devices, such as plugs and
receptacles, comprising one or more contacts, a means
for electrically attaching a conductor to each contact,
a means for electrically insulating each contact from
the other, and an overall insulating material around
the complete assembly such that only the contacts are
exposed when the connector is properly installed to the
item containing the conductors.
Generally, any item used to make an electrical
connection between two or more separate
conductors.
Connector Box
see Plug-In Box
Connector Strip
A piece of power distribution equipment comprising
an elongated metal housing, and a plurality of female
flush mount connectors or female pigtail connectors for
the purpose of supplying electricity to luminaires. It
usually hangs from a batten and has many circuits, the
line side is usually hard-wired, and it gets its
electrical supply from dimmers.
Console
see Control Console.
Control Board
see Control Console.
Control Cable
A cable used to transmit digital or analog signals
from a control console to the apparatus to be
controlled.
Control Card
Specifically, a circuit board that receives the
control signal from the control console and, in turn,
individually controls the independent outputs of a bank
of dimmer modules.
Generally, any circuit board that performs many
of the control functions of an electronic apparatus, e.
g., a ballast or automated light.
Control Console
An electronic apparatus, run by an operator, that
converts the settings of various items, such as
sliders, switches, buttons, or some form of data input,
into a digital or analog signal that is thereby
transmitted to a control card, dimmer bank, or some
other electronic apparatus. Some control consoles are
also equipped with monitors.
Convex
A term used to describe a lens side that is
outwardly and usually spherically curved.
Cool Color
Generally, a color that is in the green-blue-violet
range.
Cool Light
Light having a color temperature of approximately
3600°K to 4900°K, i.e., bright-white to
blue-white.
Cord Wrap
A loop made of rope attached to a yoke for the
purpose of supporting excess coils of electric
cable.
A round bracket provided on the rear of some
luminaires for the purpose of retaining coils of
electric cable when the luminaire is to be stored or
transported.
Crew
see Lighting Crew
CRI
Color Rendering Index
Cross Bar
In the theater industry, a bar mounted
horizontally on top of a stand. It contains two or more
sliding tees for mounting luminaires, and a fixed tee
for mounting the bar to the stand.
In the film and video industries, a bar mounted
horizontally between two stands for the purpose of
hanging luminaires or grip equipment.
Cross Connecting Panel
see Patch Panel.
Cross Fade
A relatively slow change from one control console
setting to another.
Cross Fader
A slider on a control console that enables a cross
fade.
Cross Light
A luminaire used for cross lighting.
Cross lighting
Illumination from two sources on opposite sides of
the subject.
Cue (Q)
An event in a production that is the signal for
a specific action.
The signal given in order to cause such an
action.
The response to such a signal, which may include
a change in intensity settings for a luminaire(s), or a
change in action by an apparatus(es).
Cue Light
A light used to signal a cue. Red usually means
stand by and green usually means execute the cue.
Cut
To remove illumination from a scene or
subject.
To block a portion of a light beam.
Cut Sheet
Also known as data sheet; a paper, pamphlet or
leaflet that has detailed information about a lamp,
luminaire, piece of equipment, etc., usually supplied
by the manufacturer.
Cutoff
A general term for anything used to block a portion
of a light beam, e. g., flags, cutters, shutters, barn
doors, etc.
Cyc
see Cyclorama
Cyc Light
See Cyclorama Light
Cyclorama
A vertical surface which is used to form the
background for a theatrical type setting, usually made
of heavy cloth drawn tight to achieve a smooth, flat
surface. It usually represents the sky or suggests
limitless space. Traditionally, cycloramas were dome
shaped or horizontally curved, but may now also be flat
or vertically curved as well.
Cyclorama Light (Cyc Light)
A luminaire mounted at the top and/or bottom of a
cyclorama in order to light it in a smooth, uniform
manner.
Light that has a color temperature of approximately
5500-5600°K, which has been approximated to be the
color temperature of ordinary sunlight during the day
under normal atmospheric conditions.
Daylight Booster
see Punch Light.
Daylight Filter
A filter used to balance light from a source such
that the spectral distribution will approximate
daylight, i.e. 5500-5600°K.
DC
Abbreviation for Direct Current.
DC Volts (VDC)
A unit of measurement for Voltage Potential,
specifically for direct current voltages.
Dead
Anything that is supposed to be carrying, or has
the potential to carry electrical current, but
isn't.
Dichroic
A type of metallic coating applied to glass and
some other materials that allows certain wavelengths of
light, or other electromagnetic radiation, to pass
while reflecting all others.
Diffuse
To scatter light using diffusion material.
A term used to describe a somewhat dull and/or
stippled surface that is moderately reflective.
Diffuser
Generally, something made of diffusion
material.
In the film and video industries, a fabric
panel, used for diffusing, with the light source being
a luminaire or sunlight. They are available in a
variety of sizes and shapes, and materials of varying
textures.
Diffusion Frame
An apparatus used to hold diffusion material. It
can be of various shapes and sizes, and may comprise
one or more pieces.
Diffusion Material
Any reflecting or transmitting media for which the
reflected or transmitted light is distributed
uniformly, i.e., scattered over a wide range.
Diffusion Media
see Diffusion Material.
Digital Multiplex (DMX)
A system that simultaneously transmits more than
one digital signal.
Digital-To-Analog Converter (D/A Converter)
An apparatus that converts digital signals to
analog signals.
Dim
To change the intensity of a luminaire.
The state of a luminaire at very low
intensity.
Dimmer
An apparatus used to control the intensity of a
luminaire.
Dimmer Card
A circuit board that contains some or all of the
electronic components needed to electronically dim a
luminaire.
Dimmer Module
A discrete apparatus that contains a dimmer card,
its enclosure or mounting apparatus, and perhaps other
related items such pilot lights or handles.
Dimmer Pack
A portable housing that contains a group of
electronic dimmers, usually not less than 4 or more
than 24. Some dimmer packs are designed such that they
can be permanently installed.
Dimmer Panel
An apparatus, usually 19" long, that contains a
group of electronic dimmers that get installed into a
dimmer rack.
Dimmer Rack
An apparatus designed to contain a large group of
electronic dimmers. Permanently installed dimmer racks
comprise a metal frame and housing in their
construction, and are hard wired. Portable dimmer racks
are provided with connectors for a tie-in, and are
usually provided with wheels, handles, and a metal
frame in a metal-lined wooden housing.
Dimmer-Per-Circuit
A situation or design where each electronic dimmer
used in a theater or studio affects only one
circuit.
Direct Current (DC)
An electrical current that maintains constant
direction.
Direct Current Voltage
A voltage that maintains constant polarity.
Direct Lighting
Illumination on a subject or area that goes
directly from the front of the luminaire in a straight
line to the subject or area.
Disappearing Footlight
A footlight mounted into a stage floor, that when
closed, has its lid completely flush with the floor.
The lid is usually made from the same material as the
stage floor.
Distribution
see Light Distribution.
Distribution Equipment
Any electrical apparatus that routes electrical
current to another apparatus, usually luminaires.
DMX
Abbreviation for Digital Multiplex.
DMX 512
A somewhat unique digital multiplex signal with
specific characteristics that is commonly used in the
stage and studio lighting industries. Control consoles
designed to generate this signal were originally
designed to control a maximum of 512 apparatuses,
usually dimmers, but now can control many more.
Donut
A flat metal apparatus with a circular hole in the
center used to reduce halation and sharpen the image
when using patterns.
Door
A single flap on a Barndoor.
A cover to an access opening in the housing of a
luminaire or other apparatus.
Double Ended Lamp
A somewhat elongated lamp that has a base and
contact on each end.
Double Header
A tee bar with two individual, or sets of, studs or
receivers.
Double Pipe Clamp
Two pipe clamps connected together via a short stud
with their serrated jaws on opposite ends. It is used
to connect two pipes together.
Double Pipe Clamp Extension
Two pipe clamps connected together via a narrow
pipe, usually 24" or more, with their serrated jaws on
opposite ends. It is used to connect two pipes
together.
Down Light
Downward illumination, almost perpendicular with
the floor.
A luminaire that provides such
illumination.
Downstage
The stage area nearest the audience, also
containing the apron.
Drafting Template
A translucent mask with traceable patterned cutouts
of luminaires and other items used to draw a light
plot.
Dress
To arrange electric cables in a neat and orderly
fashion.
Drop Box
see Plug-In Box.
Drop-In Iris
An iris mounted to a plate that can be installed,
i.e., dropped into or removed from a luminaire.
Duvetyn (Duvatyne, Duvetine, Duvetyne, Duvyteen)
An opaque material used for butterflies, cutters,
flags, gobos, and overheads in the film and video
industries.
The standard household male, parallel blade
connector that may or may not have a ground pin.
Edison Lampholder
The standard household screw-type lamp socket that
accepts medium screw type lamp base.
Effects Projector
A special, lensed luminaire designed to project
images by placing one or more glass, film, or plastic
slides or metal patterns into its beam. The first crude
effects projector was developed by Steele MacKay in the
late 1880's.
Egg Crate
A square or rectangular, partitioned apparatus
that, when installed on large open face luminaires,
reduces glare.
Electric
An abridged version of Electrics Pipe.
A term used by professional film and video
industry people to refer to those operating or
utilizing luminaires and related equipment, such as
cable, distribution equipment, dimmers, etc.
Electrical Distribution
see Power Distribution.
Electrical Frequency
The cycles per second of alternating current, in
Hertz. In North America, and parts of South America and
South East Asia, the frequency is 60 Hz. The rest of
the world operates at a frequency of 50 Hz.
Electrical Noise
A general term for an unwanted electronic
disturbance in conductors or electrical or electronic
equipment. This equipment can also be the cause of
electrical noise.
Electrical Panel
see Panelboard.
Electrical Supply
Anything that has the potential to provide voltage
and electrical current, i.e., electrical power.
Electrician
Generally, one versed in the field of
electricity and its application.
A term used by professional stage lighting
people to refer to those operating or utilizing
luminaires and related equipment, such as stage cable,
dimmers, etc.
Electrics
A catch-all term used to describe any type of power
distribution equipment hung from or attached to an
electrics pipe.
Electrics Pipe
A horizontal pipe on which luminaires and some
distribution equipment are hung. It should not be used
to hang scenery and/or curtains.
Ellipsoidal
An abridged version of Ellipsoidal Spotlight.
Ellipsoidal Reflector
A reflector designed to converge light rays to a
single point, except that point which is occupied by
the point source, eventually resulting in a beam that
varies in width, depending on the distance between the
two points. It has the shape of the end section of an
ellipsoid.
Ellipsoidal Reflector Spotlight (ERS)
See Ellipsoidal Spotlight.
Ellipsoidal Spotlight
A spotlight that embodies an ellipsoidal reflector
and framing shutters, and sometimes an iris and pattern
slot.
End Prong Base
A lamp base, 1/2" deep, with two flat, parallel
contacts protruding from the bottom.
Envelope
The outer glass part of a lamp.
ERS
Abbreviation for Ellipsoidal Reflector
Spotlight.
Even Field
A field that has a relatively uniform decrease in
intensity as viewed from the center to the edge of the
field, i.e., a field that does not have a noticeable
hot spot.
Extended End Prong Base
A lamp base, approximately 1-1/4" deep, with two
flat, parallel contacts protruding from the
bottom.
Extension
A catch-all term used to describe any item that
stretches the reach of, or increase the length of
something, e. g., side arms, extension arms, stage
cables, etc.
A rating often applied to scrims used in the film
and video industries on the ability to dim light. This
rating is directly related to a camera's ability to
allow for the admittance of light.
Fade
To gradually increase or decrease the intensity of
light.
Fade In
The gradual increase in intensity of light.
Fade Out
The gradual decrease in intensity of light.
Fade-To-Black
To gradually decrease the intensity of all lighting
to a blackout.
Fader
An item found on most control consoles, such as a
slider, used to fade.
Far Cyc
A cyclorama light placed at a distance from the
cyclorama, generally 8' or more.
Feed
See Electrical Supply.
Feeder Cables
A set of electric cables, usually individually
insulated conductors with a high ampacity, used to
remotely connect portable dimmer racks, power
distribution racks, and the like, to the electrical
supply. They are usually of the wire types W or SC, and
are often provided with Cam-lok connectors.
Feeders
See Leads, short for Feeder Cables.
Female
A term applied to a connector that contains the
holes and/or slots for receiving the pins, prongs,
blades and/or tabs of a male connector. The female
connector should always be attached to the line side of
a circuit.
Field
In Photometry, the circular area of the base of a
cone shaped beam where the intensity is at least 10% of
the maximum intensity. The maximum intensity is ideally
located at the center of the base. It should be noted
that some luminaires, such as ellipsoidal spotlights
and follow spots, can be adjusted or designed such that
the light emanating from them does not include the
entire field, i.e., the edge of the beam is greater
than 10% of its center.
Field Angle
The angle of the vertex of a cone shaped beam where
the perimeter of the base is defined by where the
intensity is 10% of the maximum intensity.
Field Diameter
The diameter of the base of a cone shaped beam
where the perimeter of the base is defined by where the
intensity is 10% of the maximum intensity.
Filament
The wire inside an incandescent lamp envelope that
glows and emits light when heated, i.e., when
electricity passes through it.
Fill
To create the illumination needed to reduce shadows
in an area or on a subject.
Fill Light
Supplementary illumination used to reduce
shadows, preventing them from appearing black.
A luminaire that provides such
illumination.
Filter
A term that refers to color media, diffusion
material, or neutral density filters.
Filter Frame
see Color Frame.
Fire Up
To switch on a luminaire or some other electrical
apparatus.
Firing Card
see #1 of Control Card.
First Border
The borderlight and/or its position on the first
electric.
The first teaser curtain upstage of the
proscenium arch.
First Electric
The electrics pipe and/or its position, which is
located immediately upstage of the proscenium
arch.
Fixed Focus
A term used to describe an optical system whereby
the lenses in a luminaire remain at a fixed distance
from one another, although they may move as a group
within the system.
Fixed Lens System
An optical system where the lens or lenses in a
luminaire remain stationary, i.e., they lack the
ability to move.
Fixture
A term that is often used interchangeably with
Luminaire.
Fixture Extension Clamp
A pipe clamp connected by its base to a narrow
pipe, usually 24" or more, with a bolt and washer on
the other end for the purpose of extending the mounting
position of a luminaire.
Flex Scrim
A small fabric scrim that is not intended for use
on an open end frame, i.e., they are intended to dim
the full beam.
Flicker
The strobing of some luminaires that cannot be
visually detected because of the frequency of its
output voltage, but can adversely affect the way motion
picture film records light.
Flicker-Free
A term used to describe electronic ballasts that
electronically alter the electrical frequency that
causes flicker.
Flies
The space above a stage where scenery, luminaires,
etc. are hoisted above horizontal sight lines.
Flood
The position of a movable lamp, lens, or pair of
lenses on a spotlight that produces the widest field
angle.
To direct a large amount of light on a
relatively large area.
Flood Light
A luminaire consisting of a reflector, lamp, and
sometimes a single lens, used to direct a large amount
of light on a relatively large area.
Floor Box
See Floor Pocket.
Floor Bracket
See Floor Trunnion.
Floor Pocket
A stage pocket whose cover is flush mounted with
the floor to which it is mounted.
Floor Trunnion (Floor Trunnion)
A metal bracket with a base used to support a
striplight. Always used in pairs, a trunnion attaches
to each end and can sit on a floor or can be attached
to pipe clamp for hanging. They can also be provided
with casters.
Fluorescence
The property of certain materials to absorb
radiation of certain wavelengths, usually ultraviolet,
and re-emit the radiation as light.
Fluorescent Lamp
A lamp that uses fluorescence as its light
source.
Flush Mount
A term used to describe anything whose upper
surface, when installed, is flush with the surface to
which it was installed. This term is used to describe
floor and wall pockets, disappearing footlights,
ceiling ports, and certain types of connectors.
Fly
To lift scenery, truss, luminaires, etc., into the
air by support cables, chain, or ropes, with the aid of
motors, pulleys, winches, and the like.
Fly Tower
The support structure mounted to the stage wall
that contains the ropes or cables and pulleys that go
between the flies and the flyrail or pinrail.
Flyrail
In modern theaters, it is a sturdy, steel
structure with an assortment of pulleys and
counterweights, and cam-like clamps or clutch
mechanisms which secure the ropes that support the
battens and electrics pipes. These apparatuses are
often motorized.
In older theaters, the flyrail is a
pinrail.
Foamcore
A polystyrene, styrofoam material used as a
substrate for some reflector boards, effective because
of its light weight and ease of mounting via reflector
forks.
Focal Length
The distance between a particular point of a lens
or reflector, and the focal point.
Focal Plane
The plane that is perpendicular to the axis of an
optical system and also contains the focal point.
Focal Point
The small region where a lens or reflector
concentrates the light from a light source.
Focus
To aim and adjust a luminaire to give the beam
its desired size (spot or flood), edge (soft or hard),
field (even or peak), and/or shape (round, patterned,
or cut).
To aim and adjust a lens, pair of lenses, light
source, reflector, or any combination of these so that
the light is concentrated at the focal point.
Focus Lens
A movable lens in a multi-lens optical system that
adjusts the focus of a luminaire.
Focus Range
The ratio of spot focus to flood focus.
Focusing Instrument
A luminaire whose beam can be adjusted from spot
focus to flood focus.
Follow Spot
A narrow-beam focusing instrument that is manually
operated, and usually comprises a powerful light
source, an iris, shutters, a color changer, and perhaps
other features. It is usually operated from an
adjustable stand and is used to follow performer(s) on
a stage with its beam, surrounding the performer(s) in
a large pool of light.
Foot
The very front of the stage.
Footcandle (fc)
A non-metric unit of measurement for Illumination,
i.e., 1 lumen per square foot.
Footlight
A luminaire, often a striplight, that is used from
the floor of a stage, runway, or other performing area.
This luminaire received its name because it was
originally used to illuminate the feet of dancing
performers on stage.
Framing Projector
A spotlight that has framing shutters.
Framing Shutters
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.
Frequency
The speed at which something pulses or
cycles.
An abridged version of Electrical
Frequency.
Fresnel
short for Fresnel Spotlight.
Fresnel Spotlight
A spotlight employing a single fresnel lens that
produces a soft edged beam, and usually provided with a
spherical reflector and a means to adjust the focus
from spot to flood.
Front Light
Illumination from the general direction of the
viewer(s).
A luminaire that provides such
illumination.
Front-of-House (FOH)
The complete area of the theater in front of the
stage, i.e., the audience area.
Frost
A term used to describe a lamp whose envelope
has been stippled to the point of being translucent for
the purpose of diffusing the light. A type of
colorless diffusion material made of glass fibers or
high-temperature plastic.
Full Scrim
A metal scrim whose screen occupies the complete
frame.
Full Stage Plug
A wide, male slip connector designed to carry a
relatively large amount of current.
Funnel
see Snoot.
Fused Quartz
A relatively pure, high-temperature glass used to
manufacture lamp envelopes. It has a melting point of
approximately 1650°C.
A term used by professional film and video industry
lighting people to refer to someone overseeing those
operating or utilizing luminaires and related
equipment, such as electric cables, dimmers, etc.
Gaffer Grip
A large, spring-loaded clamp with serrated or
rubber cushioned jaws. It usually has a stud or studs
for the attachment of luminaires and grip
equipment.
Gas Light
A luminaire that uses burning gas as its light
source.
Gel
An abridged but commonly used version of
Gelatin.
To place gelatine in front of a luminaire to
alter the color of the beam.
Gel Frame
See Color Frame.
Gel Scroller
See the definition for Color Scroller.
Gel String
A series of different color gels connected together
in a row for use in a color scroller.
Gelatine (Gelatin)
A type of color media originally made from
gelatine, an organic substance made from animal
tissues, but now refers to color media made from very
thin high-temperature plastic as well.
Generator
An electrical supply, usually portable, that
comprises a diesel or gasoline powered machine and
electromagnets for the purpose of generating
electricity.
Ghosting
A term used to describe a filament, lamp or
luminaire that is barely glowing.
Glitch
An unintended surge or brief interruption in an
electrical current or signal. This can sometimes be
detrimental to the integrity of the signal or to
electronic equipment.
Any error in the execution of a cue from a
control console.
Go Button
A button on a control console that executes a
cue.
Gobo
See definition for Pattern.
In the film and video industries, a general term
for any opaque item placed into the beam of a luminaire
that blocks a portion of the beam or the whole
beam.
Gooseneck
A small worklight, supplied with some control
consoles and other equipment, that has a long, narrow,
adjustable support, similar in appearance and mobility
to the neck of a goose. They are usually removable and
dimmable.
Graduated Scrim
In the film and video industries, a round, framed
metal screen whose density gradually decreases from one
side of the frame to the other.
Grand Master
A slider on a control console that controls all
other sliders on the console, including masters and sub
masters.
Grid
The wood or metal framework located in the flies
that supports the pulleys containing the steel wires or
rope holding up scenery, battens, etc.
The metal structure of pipes in a studio ceiling
for the purpose of hanging luminaires, power
distribution equipment, or grip equipment. A ballast
for carbon arc spotlight.
Gridiron
A grid made of iron and/or steel.
Gridiron Junction Box
A piece of distribution equipment that houses
electrical connections. Although quite often located on
a gridiron, it can be located anywhere in the stage
area or flies where electrical connections need to be
made and protected.
Grip
A term used by professional film and video
industry lighting people to refer to someone utilizing
grip equipment and other related items.
An abridged version of Gaffer Grip.
Grip Equipment
A catch-all name for portable items that a member
of a film or video industry lighting crew may use, such
as luminaires, stands, clamps, flags, cutters, scrims,
nets, dots, fingers, etc.
Ground
A conducting connection between an electrical
circuit or electrical equipment and earth, or to some
conducting item that serves in place of the earth. In
most alternating current circuits, ground has a voltage
potential of zero.
Ground Cyc
A cyclorama light used from the floor.
Ground Pin
The pin, prong, blade, or tab on some male
connectors for the purpose of making a connection
ground.
Ground Row
A piece of scenery placed upstage to suggest items
near the horizon, often used to hide ground cycs from
view of the audience.
Ground Row Cyc
A cyclorama light placed between the ground row and
the cyclorama.
Ground Support
The truss, lifts, towers, etc. that are set up at
ground, stage, or platform level and used to support
other truss or equipment above.
A metal scrim whose screen occupies one half of its
frame such that the straight edge of the screen is
located at the diameter of the frame.
Halogen
The name for a family of gases used in lamps to
maintain proper color temperature and to keep the
inside wall of the envelope clean.
Hanging Arm
A metal bracket with a pipe clamp on one end used
to hang short (generally less than 10') striplights
from a batten. Always used in pairs, a hanging arm
attaches to each end of the striplight.
Hard Light
Illumination that has a hard edge and produces
sharply defined shadows. Often this light is very
intense.
A luminaire that provides such
illumination.
Head
A general term for a fresnel spotlight.
The part of a follow spot that contains the
light source, i.e., not the stand, ballast, or
interconnect cable.
The part of a metal halide luminaire that
contains the lamp, i.e., not the ballast or
interconnect cable.
The part of an ellipsoidal spotlight that
contains the reflector, i.e., not the lens barrel or
the cap.
Heat Filter
A filter which transmits visible light and either
absorbs or reflects infrared in order to reduce the
amount of heat in a beam.
Heat Shield
A thin, heat-resistant metal plate(s) that
surrounds a lamp base in order to reduce the amount of
heat reaching the lamp socket in order to reduce pinch
temperatures.
Heat Sink
A metal form whose sole purpose is to absorb heat
on one surface and radiate that heat from other
surfaces.
HMI
Abbreviation for Hydrargyrum (Greek for Mercury)
Medium-Arc Iodides. This is a commonly used type of
metal halide lamp manufactured by Osram-Sylvania Corp.
The term Osram HMI is trademarked.
Horizontal Sight Lines
Imaginary lines drawn from the seats furthest from
the center line of the audience area, to any
obstructions on the sides of the stage, to determine
what portions of the performing area will be visible to
all of the audience.
Hot Patch
To make a connection on a patch panel while the
circuit is live, thereby creating a potentially
dangerous arc.
Hot Spot
The spot of light with the highest intensity,
ideally located at or near the center of a beam that
has been focused for a peak field.
House Electrician
The electrician employed by a facility who is in
control of house lighting and any electrical or
electronic equipment owned or responsible for by the
facility.
House Lights
General lighting provided for the audience
area.
Hue
The red, orange, yellow, green, blue, violet,
magenta aspect of color, without regard to other
aspects such as saturation and luminance, i.e.., the
property of light that distinguished it from gray of
the same luminance.
To cause an arc to form across the electrodes of a
light source, either manually, as with carbon arc
sources, or by using an ignitor, as with arc
lamps.
Illumination (E)
Generally, a term for light or lighting.
In photometry, the amount of light, i.e..,
luminous flux per unit area incident on a surface, in
Footcandles or Lux.
Image
The actual design of a pattern.
The reproduction of an object formed by an
optical system.
Incandescence
The emission of light from heated objects.
Incandescent
A term used to describe a lamp, or a luminaire that
utilizes such a lamp, that employs the incandescence of
a filament as its light source. Such a lamp was first
developed by Thomas Edison (United States) and Joseph
Swan (Great Britain), independently, in 1879.
Indirect Lighting
Illumination that falls on an area or subject by
reflection, e. g., bounce lighting.
Inky
A small fresnel spotlight with a 1.5" to 3" lens
diameter, usually 100-250 watts.
Inlet
a recessed male connector.
Instrument
In the theater industry, another term for
Luminaire.
Integrated Circuit (IC)
An electronic component that includes circuits,
rectifiers, and perhaps transistors and other
electronic components, processed and contained entirely
within a single, compact package with terminals for
making electrical connections.
Intelligent Light
see the definition for Automated Light.
Intensity
An abridged version of Luminous Intensity.
Interconnect Cable
An electric cable and connector assembly that
electrically connects a ballast to a luminaire that
uses an arc as its light source.
Interconnecting Panel
See thdefinitionon for Patch Panel.
Iris
An abridged, but commonly used version of Iris
Diaphragm.
Iris Diaphragm
An arrangement of thin, movable, heat-resistant
metal plates, i.e.., leaves, that form an adjustable
circular opening. They are usually placed within an
ellipsoidal spotlight or follow spot in order to adjust
the diameter of the beam, or in some cases, to
mechanically dim the beam.
Iris Slot
A narrow opening in some luminaires for the purpose
of inserting a drop-in iris.
In the metric system, a graduated scale used to
measure temperature with 0° (-273°C) being the
total absence of heat (absolute zero). Each degree is
the same magnitude as a degree in the centigrade
scale.
Key Light
the principal source of light which establishes the
character of the actor together with the atmosphere and
mood of the scene.
Kill
To disconnect electrical current to one, some, or
all luminaires, motors, or other electrical
equipment.
Any light source in a self contained package,
comprising an envelope, filament or electrodes, base,
contacts, gas, and any support structures. The source
can be of the incandescent, fluorescent, or arc
type.
Quite often this term is used interchangeably
with Luminaire, especially in the theater
industry.
To install a lamp in a luminaire.
Lamp Bar
A pipe, usually aluminum, that has a plurality of
luminaires attached at even intervals. The power cords
for the luminaires enter the pipe at even intervals.
The power cords for the luminaires enter the pipe via a
strain relief, and are electrically connected to wires
within the pipe. The internal wires usually terminate
into a multiconnector.
Lamp Dip
A colored transparent or translucent lacquer used
on low-wattage incandescent lamps in those instances
when it is not practical or possible to use standard
color media.
Lampholder
The electrical device that supports a lamp in a
luminaire, and generally contains the contacts that
make the electrical connection to the contacts of the
lamp base.
Lantern
A term that is often used interchangeably with
Luminaire, and is preferred over Luminaire in
Europe.
Leads
The electric cable(s) or sleeved, insulated wires,
attached to a luminaire or piece of power distribution
equipment via a strain relief, that terminate in a
connector for the purpose of providing an electrical
connection to the electrical supply or to another
luminaire.
Leaf
A single thin, heat-resistant metal plate from
an iris or some mechanical dimmers.
See definition #1 for Door.
Leko
A commonly used term for an ellipsoidal spotlight.
Named after its inventors Levy and Kook, the names Leko
and Lekolite are trademarked by Strand Lighting
Co.
Lekolight
See the definition for Leko.
Lens
A transparent material, usually glass, shaped to
bend light rays as they pass through it. Colored lenses
can also be used as color media.
Lens Barrel
The movable, inner tube of a focusing lens
system in an ellipsoidal spotlight.
The complete tubular front section of an
ellipsoidal spotlight that contains the lenses.
Lens Holder
Any apparatus used to retain a lens.
See definitions #1 and #2 for Lens Barrel.
Lens Size
A term used in the theater industry to describe
plano-convex or bi-convex lenses in terms of diameter
and focal length (in inches), e. g., 6x9, 4.5x12.
Generally, the diameter of a lens.
Level
An abridged version of Light Level.
The position of a slider on a control
console.
Lift
A height adjustable stand or tower, sometimes
motorized or operated with a crank mechanism or by gas
or liquid pressure.
Light
Illumination, i.e.., the aspect of radiant
energy of which a human observer is aware through the
visual sense. Its electromagnetic shorter than infrared
radiation, i.e.., approximately 380nm (violet) to 750
nm(red). A term that is often used interchangeably
with Luminaire.
Light Console
See the definition for Control Console.
Light Distribution
The way in which illumination of any color or
quantity is spread over a particular background.
Light Ladder
A steel or iron, ladder-like apparatus used to hang
a plurality of luminaires.
Light Leak
Unwanted light that escapes a luminaire from a
location other than its intended opening.
Light Level
The average illumination on a subject, performing
area, or part thereof.
Light Meter
Any apparatus used to measure various quantities of
light, i.e.., color temperature, footcandles, lux,
etc.
Light Plot
The diagrammatic layout of luminaires and related
equipment, and their application(s) for a lighting
production.
Light Source
Anything that emits light, such as an arc or a
filament, or in early stage light, the flame of a
burning wick or gas.
Light Spill
A general term used to describe any stray light,
including light leak.
Light Tree
A stand with arms attached.
Lighting Crew
A group of individuals trained in lighting skills
and techniques, and collectively assembled to work on a
stage, film, or video production. The group may include
any or all of the following stagehands: electrics,
electricians, roadies, gaffers, grips, operators and
lighting technicians.
Lighting Design
The complete layout and presentation of the
lighting designer.
Lighting Designer
One who plans lighting compositions, lays out light
plots, directs the focusing of luminaires, and
determines the various intensities, colors, looks, and
cues for a lighting production.
Lighting Director
One who is responsible for the execution of the
lighting design for a production, and, in some
instances, may also be the Lighting Designer.
Lighting Grid
See the definition for Grid.
Lighting Technician
One trained in the lighting skills and
techniques necessary for the implementation of the
lighting design for a particular production.
See definition #2 for Electrician.
Liquid Dimmer
See the definition for Salt Water Dimmer.
Live
Having any voltage potential in reference to
neutral or ground.
Load Rating
The maximum electrical load that something, such
as wire, fuses, electrical connectors, etc., can safely
accommodate.
The maximum weight that something can safely
accommodate.
Location Fresnel
A fresnel spotlight used primarily in non-standard
production settings, i.e.., locations other than stages
or studios. Because portability is generally a concern,
they tend to be smaller in size when compared to studio
fresnels of the same wattage.
Long Throw
A term used to describe a luminaire that has an
effective intensity at a relatively long distance. This
term is very subjective and dependent on the type of
luminaire used.
Lowboy (Loboy)
A heavy-duty stand designed to hold luminaires or
heavy grip equipment. The stand is equipped with wheels
and short risers, and a 1-1/8" receiver and a grip
head.
Lumen
A unit of measurement for Luminous Flux.
Luminaire
A complete unit for the purpose of generating
usable and somewhat controllable light that comprises
one or more lamps, parts designed to distribute the
light, parts used to position and protect the light
source, and a means to connect the light source(s) to
an electrical supply.
Luminance
A measure of the light, i.e.., luminous flux, per
unit area leaving a surface in a particular direction.
This quantity was formerly known as Brightness.
Luminous Intensity (I)
A measure of the strength of a light source in a
particular direction, in Candles or Candelas. It is
independent of the distance from the source.
Lux
A metric unit of measurement for Illumination,
i.e.., 1 lumen per square meter.
A term applied to a connector that contains the
pins, prongs, blades, and/or tabs for insertion into
the holes or slots of a female connector. The male
connector should never be attached to the line side of
a circuit.
Master
A slider on a control console that controls
groups of sliders on the console, including some or all
sub masters, with the exception of the grand master, if
the console is so equipped.
A term used to describe a control console that
has control over another control console(s).
Master Electrician
In the theater industry, the supervising
electrician on a production, i.e.., the person
ultimately responsible for all other electricians,
luminaires, and related equipment, such as stage cable,
dimmers, etc.
Matrix
A patching apparatus that can be a patch panel or a
diode pin matrix.
Medium Base
A lamp base that falls in the middle range of sizes
for the type of base in question, i.e.. approx. 1"
diameter for screw and prefocus type bases, approx.
7/8" post-to-post distance for bi-post bases, approx.
3/8" pin-to-pin distance for two-pin bases, and approx.
1/2" prong-to-prong distance for side prong bases.
Medium Throw
A term used to describe a luminaire that has an
effective intensity at a relatively moderate distance.
This term is very subjective and dependent on the type
of luminaire used.
Memory Board
A control console that has computerized functions
and an ability to electronically store data.
Midget
See the definition for Inky.
Mini Strip
A compact striplight that uses 1 to 4 groups of ten
12 volt lamps wired in a series circuit, manufactured
by Lighting & Electronics, Inc. The name Mini Strip
is trademarked.
Mirror Ball
A sphere whose surface is covered with a plurality
of small, individual mirrors, that when rotated and
shined upon by a light source, gives the effect of a
multitude of moving spots of light swirling and
sweeping across surrounding surfaces.
Module
An abridged version of Dimmer Module.
Mogul Base
A lamp base that falls in the larger range of sizes
for the type of base in question, i.e.., approx. 1-1/2"
diameter for screw and prefocus type bases, approx.
1-1/2" post-to-post distance for bi-post bases, and
approx. 11/16" prong-to-prong distance for end prong
and extended end prong bases.
Monitor
An apparatus that renders a visual representation
of the instructional information that was, is, or will
be sent from a control console to a control card,
dimmer bank, or some other electronic apparatus, and
also a visual representation of the status of these
items.
Moving Light
See the definition for Automated Light.
Multi Cable
An abridged version of Multiconductor Cable.
Multiconductor Cable
An electrical cable that generally has more than
three conductors.
Multiconnector
A connector that generally has more than three
contacts.
Muslin
A material used for fabric scrims used in the
theater, film, and video industries.
A unit of measurement for Resistance, Reactance, or
Impedance.
Ohm Meter
An apparatus that measures resistance.
Ohm's Law
A basic electrical formula that simply states that
voltage is equal to electrical current multiplied by
resistance, i.e.., V=IR.
Onstage
In sight of the audience.
Open Circuit
A circuit that has a physical break or
disconnection, whether intentional or accidental, in
its electrical path.
Open End
A term used to describe a U shaped mounting frame
for a scrim that supports the scrim on three sides,
allowing the fourth side to remain free from a frame
section. When this side is partially introduced into
the beam, the straight edge of the dimmed portion of
the beam casts no dark shadow line.
Open Face
A term used to describe luminaires that use no
lenses.
Operating Light
A work light used by the operator of a control
console.
Operating Pole
A long, lightweight rod with a handle on one end
and an attachment on the other for the purpose of
adjusting or switching on pole-operated yokes,
luminaires, pantographs, etc.
Operator
A person designated to operate a control console,
follow spot, generator, or some other apparatus that
requires some degree of training and/or skill to
use.
Outlet
A female connector.
Outriggers
Sturdy support legs that assist in stabilizing some
stands and lifts. They are generally removable or
easily folded away to assist in transporting or
maneuvering the stand or lift.
To rotate from side to side around a vertical
axis.
Panel
A general term that can refer to an overhead,
butterfly, or large framed scrim, diffuser, or
reflector.
An abridged version of Breaker Panel, Circuit
Breaker Panel, Electrical Panel, or Panelboard.
Panelboard
A piece of power distribution equipment comprising
a box-like metal enclosure with a hinged cover,
accessible only from one side, to allow access to
internally mounted circuit breakers, switches, and
fuses.
Par
An abridged version of Par Lamp, Par Can, or Par
Light.
Par Can
See the definition for Par Light.
Par Light
A generally lightweight luminaire that utilizes a
PAR lamp. The beam characteristics depend on the type
of PAR lamp used.
PAR-Lamp
A designation for a type of lamp. In the case, one
with a parabolic aluminized reflector.
Parabolic Reflector
A reflector designed to align light rays generally
parallel to the axis formed by the point source and the
center of the reflector, eventually resulting in a
cylindrical-to-wide beam. The reflector has the shape
of a paraboloid.
Patch
To make electrical connections on a patch panel,
i.e.., hard patching, or, to assign dimmers to channels
on a control console, i.e.., soft patching.
Patch Bay
See the definition for Patch Panel.
Patch Panel
A large, metal cabinet that comprises a plurality
of female connectors electrically connected to dimmers,
and a plurality of patch cords for the purpose of
changing around the load(s) that are connected to the
dimmer(s). Some patch panels use parallel bus bars
electrically connected to dimmers, and another set of
parallel bus bars mounted 90° to the first set and
electrically connected to the loads, and slidable
connectors that electrically connect any bus bar from
one set to any bus bar from the other set.
Pattern
A very thin, heat-resistant metal plate with a
design cut out of its surface. When placed into the
aperture of an ellipsoidal spotlight or follow spot via
the pattern slot, an illuminated representation of the
design is projected.
A metal frame with a knob used to place patterns
into the pattern slot of a luminaire.
Pattern Rotator
A motorized pattern holder that spins the
pattern.
Pattern Slot
A narrow opening in some luminaires for the purpose
of inserting a pattern holder or pattern rotator.
Phase
The fraction of a cycle through which a wave has
passed at any instant, measured as an angle with
360° representing one complete cycle. "Phase" is
often symbolized by Ø.
Photometry
The science of measuring light and its
properties.
Pigtail
The relatively short electric cable, power cord, or
leads on a luminaire or piece of power distribution
equipment that may or may not have a connector
installed.
Pigtail Connector
A connector that is installed on a pigtail.
Pin
A thin prong used as a contact on some male
connectors and lamp bases.
Pin Connector
A type of connector in which the male comprises
three elongated, cylindrical shaped linear contacts,
and the female comprises three linear contacts with
cylindrical holes. Older versions had only two contacts
due to the fact that there was no provisions for a
ground connection.
A type of insulated, single conductor cable
connector used in the film and video industries.
Pin-Beam Spotlight
See the definition of Pinspot.
Pinspot
A spotlight that has an extremely narrow beam.
Pinspot Adapter
An apparatus placed on the front of some luminaires
in order to make the beam extremely narrow. Most have
lenses and some have framing shutters or other devices
to shape the beam.
Pipe
A long, hollow, cylindrical bar made from iron
for strength, used for battens, booms, gridirons,
etc.
See the definition for Batten.
Pipe Clamp
A "C" shaped clamp with jaws that attaches onto a
pipe and locks with the aid of a bolt, that when
tightened, bites into the pipe and locks the clamp in
place. It also has a secondary bolt for the attachment
of luminaires, distribution equipment, etc.
Pipe Mount
A term used to describe something that has a means
for mounting itself to a pipe.
Plano
A term used to describe a lens side that is
perfectly flat.
Plano-Convex Lens
A lens that is plano on one side and convex on the
other. These lenses converge light rays passing through
them.
Plug
A male connector.
Plug-In Box
A piece of power distribution equipment comprising
a metal housing, and one or more female flush mount
connectors or female pigtail connectors for the purpose
of supplying electricity to luminaires. It usually has
several circuits, its line side is usually hard-wired,
and often gets its electrical supply from dimmers.
Pocket
An abridged version of Stage Pocket, Floor
Pocket, or Wall Pocket.
A socket on a patch panel.
Pole-Operated
A term used to describe a luminaire, yoke,
pantograph, or other apparatus that can be controlled
via an operating pole.
Power (P)
A general term that can mean heat, candlepower,
and/or wattage.
Power Distribution (PD)
A term used to describe electrical equipment that
is specially designed to intake electricity and route
it to an output wiring device or devices. Wire,
electric cable, and other electrical such as circuit
breakers, terminal blocks, connectors, etc., are some
of the items employed by power distribution
equipment.
Power Supply
See the definition for Electrical Supply.
Pre-Focus Base
A cylindrical shaped lamp base with a flange around
the top to hold it into its socket. The flange fits
into the socket only one particular way such that the
filament ends up in a predetermined orientation, i.e..,
it ends up pre-focused. It has one contact on the
bottom and the flange acts as the second contact.
Pre-Rigged Truss
A truss section, usually provided with wheels, that
has lamp bars installed.
Preset
An abridged version of Scene Preset.
To have something on a control console set up in
advance of need.
Primary Colors
Colors in terms of which all other colors may be
described, or from which all other colors may be
evolved by mixtures. In light, the primary colors are
red, green, and blue. Combined in pairs, two primary
colors give the complementary color of the third. All
three colors combine to form white light.
Projecting Lens
The lens in an optical system that converges light
rays sufficiently to bring them to a clear, defined
focus.
Projection Lens
See the definition for Projecting Lens.
Proscenium
The architectural opening on a stage through which
the audience views the performance.
Protocol
The specific type of digital or analog signal, AMX
or DMX 512 e. g., used by a control console and the
equipment it controls.
Punch Light
A high intensity luminaire that floods an area with
light whose color temperature is approximately that of
daylight, often comprising a plurality FAY lamps.
A piece of power distribution equipment comprising
a small, metal enclosure housing four, flush, female
connectors, and a permanently installed power cord
whose conductors are electrically connected to the
female connectors.
An abridged version of
Dimmer Rack or Power
Distribution Rack, or an apparatus that is a
combination of the two.
Rain Light
A pinspot generally hung overhead with its beam
aiming downward.
Range
A term that usually means Throw Distance, but
sometimes refers to Beam Diameter or Field
Diameter.
Rated Lamplife
The total length of time that a lamp should operate
effectively, as set by the manufacturer.
Reactor
A ballast that uses an electromagnetic component to
limit current flow.
Reflector
Generally, anything that caused reflection.
A metal or glass apparatus, usually curved in
some manner, used in most luminaires for the purpose of
directing light rays from a light source. In the
film and video industries, a metallic or reflective
fabric panel, used for bounce lighting, or simply to
redirect light, with the light source being a luminaire
or sunlight. They are available in a variety of sizes
and shapes, and materials of varying reflectance.
Relamp
To replace a lamp in a luminaire
Relay
A contractor that generally handles less electrical
current that a standard contractor, and often gets
mounted via a relay socket.
Response Time
The time it takes for a dimmer to reach its
intended level from the initiation of an input control
signal.
the time it takes a lamp filament to react to a
change in voltage.
Rig
A complete structural assembly for hanging or
supporting luminaires, scenery, and/or other production
equipment comprising come or all of the following:
truss, motors, support cables, clamps, pulleys, pipes,
and other hardware, for the purpose of creating a
somewhat portable and temporary performing area.
To set up and connect support items, such as
cables, ropes, pulleys, hoists, motors, chains,or
slings between the points and the items to be
flown.
Rigger
A person who rigs.
Rigging
Generally, the support items used by rigger, such
as cables, ropes, pulleys, hoists, motors, chains,
slings, etc.
Risers
The ridged surfaces on a fresnel lens or a
stepped lens between sections of the active lens
surface. They are sometimes opaqued with black ceramic
enamel to reduce stray light rays.
Flat platforms of various sizes, usually
portable, used for supporting luminaires or other
production equipment, or sometimes used as portable
stages.
The pipes or tubes that make up a telescoping
stand.
Road Case
A sturdy, rugged box, often supplied with handles,
and castors or wheels, used to transport and protect
production equipment such as control consoles, dimmer
racks, luminaires, and related equipment.
Roadie
A member of a production work crew that travels
with a touring production from facility to
facility.
Roundel (Rondel)
A round piece of glass that can be used as a lens,
a color medium, and or a lamp protector.
A steel cable that has a clip on one end and a loop
on the other. It is intended to be threaded through a
piece of hanging equipment and around a support
structure, such as a batten or truss, and then clipped
to its loop. It then acts as a safety support should
the primary support, such as a pipe clamp or hanging
arm, fail.
Safety Mesh
A metal wire mesh, placed at the front of a
luminaire, designed to retain large pieces of broken
glass should the lens break.
Safety Screen
A metal wire screen, placed at the front of an open
face luminaire, designed to retain large pieces of
broken glass should the lamp break.
Safety Switch
A switch that disconnects electrical current to
any uninsulated conductor that a person may come in
contact with internally when a housing door is opened
or damaged. The switch is automatically activated by
the door or some part of the door, e. g., a lens.
A switch that disconnects electrical current to
an apparatus if the apparatus or any part experiences
an overtemp situation.
Salt Water Dimmer
An early resistance dimmer that used a container of
salt water as its resistor. The distance between two
electrodes placed into the solution is varied in order
to change the resistance between them.
Saturation
The aspect of color that determines the difference
from white at a constant hue, i.e.., the property of
any color that distinguishes it from a gray of the same
brightness. High saturation is one with little or no
white light added to the color, deep red e. g. Low
saturation is one with a large amount of white light
added to the color, light pink e. g.
Scene Master
A single slider that controls a scene preset on a
control console.
Scene Preset
A set of predetermined light levels that can be
set up on a control console in advance of need, and to
which the operator may fade or go to when desired.
A term used to describe a control console that
has such a capability.
Scenery Bumper
A large, ring-shaped stand-off, that when mounted
to a batten, prevents anything on that batten from
interfering with scenery or curtains raised or lowered
on an adjacent batten.
Scissor Hanger
A mounting apparatus comprising a stud connected to
a scissor-like clamp designed to attach to the metal
gridwork of a hung or drop ceiling.
Scoop
Named for its scoop-like shape, an open face flood
light with a large, diffused reflector that is
essentially the body of the luminaire. The reflector is
parabolic, spherical, or ellipsoidal, and is generally
made from unpainted aluminum.
Screw Base
A threaded, cylindrical shaped lamp base with a
single contact on the bottom. The threaded part of the
base holds the lamp into its socket and acts as the
second contact.
Scrim
In the theater industry, a thin, gauze-like
curtain. When illuminated from the front, it appears
opaque, and when illumination is present behind it but
not on it, the scrim becomes almost transparent. It can
also appear translucent when there is some illumination
directly on it, and some illumination present behind
it, in the proper proportions.
In the film and video industries, a fabric
panel, used for dimming, with the light source being a
luminaire or sunlight. They are available in a variety
of sizes and shapes, and materials of varying
density.
In the film and video industries, a round,
framed metal screen, available in various densities,
placed on the front of a luminaire to act as a dimmer.
They are also available such that only half of the
frame is screened, therefore allowing for only a
portion of the light beam to be dimmed.
Scrim Set
A set of metal scrims comprising a full double
density, half double density, full single density, and
half single density.
Scroller
An abridged version of Color Scroller.
Sealed Beam Lamp
A lamp with an integral light source, reflector,
and lens, all of which are either sealed within, or are
a part of the envelope.
Sharktooth
A material used for fabric scrims used in the
theater industry.
Shin Buster
A luminaire placed as close to the stage floor
as possible. It is focused such that no light shines on
the floor, thus giving the illusion that the subject is
floating. Generally, any luminaire mounted close to
the stage floor.
Short Throw
A term used to describe a luminaire that has an
effective intensity at a relatively short distance.
This term is very subjective and dependent on the type
of luminaire used.
Shutter Blade
A single framing shutter.
Shutters
An abridged version of Framing Shutters.
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.
Side Arm
In the film and video industries, any apparatus
with a pipe or rod that attaches to another pipe or
stand via some type of clamp on one end, and has a stud
or receiver on the other end for mounting a luminaire
or grip equipment.
In the theater industry, a length of narrow
pipe, containing one or more sliding tees, with a pipe
clamp attached to one end and a rivet through the other
end to retain the sliding tees. It is used to extend
the mounting position of a luminaire(s).
Sight Lines
Imaginary lines drawn from the most extreme seats
in the house to the performing area to determine what
portions of the performing area will be visible to all
of the audience.
Single Ended Lamp
A lamp that has only one base and all of its
contacts on the base.
Single Phase
A term for an alternating current electrical
supply that has one hot leg and a neutral leg, or, two
different hot legs whose phases are 120° apart,
with or without a neutral leg.
A term used to describe something that requires
a single phase electrical supply to operate.
Slider
A small, linear potentiometer often used as a
setting adjuster on a control console.
The mechanism on some patch panels that makes
the electrical connection between two bus bars.
Snoot
A metal tube, available in various sizes and
shapes, that mounts on the front of some luminaires to
control light spill. Some snoots used in the film and
video industries have a means to install circular
rings, i.e.., apertures, to the front in order to
change the size of the opening.
SO Cable
A type of hard service, oil resistant electric
cable rated for extra hard usage.
Socket
Derived from "Sockett", see the definition for
Lampholder
A female connector.
A hollow, cylindrical shaped mounting item used
to accept studs, generally equipped with a tee-handle
or bolt for setting into the stud. This prevents the
receiver-stud combination from unintentionally
uncoupling, and can also prevent the stud from rotating
within.
A relay holding device that comprises terminals
for making electrical connections to the socket, and
contacts that make the electrical connections to the
relay.
A miniature hole with two internal contacts on a
diode pin matrix for the insertion and electrical
connection of diode pins.
In general, any threaded, round opening.
The part of a carbon arc luminaire that holds
the carbon rods.
Soft Edge
A beam pattern edge that is not very clear and
distinguishable, i.e.., one with a fuzzy or blurry
perimeter.
Soft Light
Illumination that produces shadows with a soft
edge.
A luminaire that provides such
illumination.
Soft Patch
A term used to describe a patch system whereby the
dimmers can be interchangeably assigned to any one of
any number of channels. This type of patch system is
usually found on memory boards.
Solid State
A general term used to describe an electronic
component that uses immobile solids, usually
semiconductors, to do what moving parts, liquids or
gases once did. Transistors, thyristors, and diodes are
examples of solid state components.
A term used to describe an apparatus that uses
these components.
Solid State Relay (SSR)
A relay that uses thyristors in lieu of an
electromagnetically operated switch. These items are
usually available in a small, cube shaped, low profile
package with terminals for making the electrical
connections.
Spill Ring
A metal plate placed around the lamp socket base of
some luminaires to prevent light leak.
Split Cross Fader
A pair of sliders on a control console that
performs a cross fade when moved side by side, or can
be moved independently to adjust two separate control
settings at different rates.
Splitter
Generally, any connector that is electrically
connected to two or more other connectors, all
constructed as a single unit.
A twofer or a threefer.
Spot Light
Generally, any of several types of luminaires
capable of emitting a beam pattern that is round, or in
some instances, oval in shape, but more specifically
this term refers to fresnel spotlights, ellipsoidal
spotlights, and follow spots.
Stage Left
The left side of the stage when facing the
audience.
Stage Light
A luminaire intended to illuminate any portion of,
or anything on, a stage or similar performing area,
exclusive of practical lights and work lights.
Stage Plug
A male pin connector.
A male slip connector.
Stage Pocket
In the theatre industry, a piece of flush
mounted power distribution equipment comprising a metal
box with a hinged, protective cover, notches in the
cover to allow for stage cable to enter the cover in
the closed position, and one or more female connectors
mounted internally for the purpose of supplying
electricity to luminaires, or other electrical
apparatuses. Its line side is hard wired.
In the film and video industry, a female slip
connector.
Stage Right
The right side of the stage when facing the
audience.
Stagehand
One trained in the physical skills and techniques
necessary for the implementation of a stage
production.
Stand Adapter
An apparatus used for converting one type of
mounting hardware attached to a stand, such as a pin e.
g., to another, such as a receiver.
Stand By
To be prepared to receive and hence execute a new
cue, or to have just received a signal that a new cue
is imminent.
Stepped Lens
A lens consisting of tiered, concentric rings on
one side that are segments of the flat portion of a
plano-convex lens. The other side is convex. It
controls the light similar in manner as a plano-convex
lens.
Stippled
A term used to describe a surface that is dimpled
or covered with small indentations or bumps.
Strain Relief
An item mounted to a piece of electrical equipment
or a luminaire designed to retain a permanently
installed power cord such that any reasonable pull or
twist on the power cord will not cause the power cord
to get damaged at the point of entry, fall out, or
adversely affect the conductors within the electrical
equipment, luminaire, or electrical connector.
Striations
Stripes or bands of light in a beam pattern,
usually undesirable.
Strike
See the definition for Ignite.
To remove all lighting and related equipment for
storage and/or transport when a production is
over.
Striplight
A multi-lamp luminaire with its lamps mounted in a
straight row.
Strobe
To cause an intense light source to turn on and
off repeatedly at a relatively fast rate. This is
usually done in an area devoid of all other
illumination to create a flickering, slow motion
effect.
An abridged version of Strobe Light. usually
using an arc lamp as its light source.
Studio Fresnel
A fresnel spotlight used primarily in studios for
the film and video industries. Because portability is
generally not a concern, they tend to be larger in size
when compared to location fresnels of the same
wattage.
Sub Master
A slider on a control console that controls groups
of sliders on the console, and perhaps other sub
masters. They can usually be controlled by masters and
the grand master if the console is so equipped.
Subtractive Color Mixing
The removal of energy from various wavelengths of
light, usually by filtering. When filters are
superimposed, each tends to remove energy at the
wavelengths it would have if acting independently.
Surface Mount
A term used to describe anything whose bottom
surface, when installed, is flush with the surface to
which it was installed. This term is used to describe
certain types of connectors, lamp sockets, plug-in
boxes, and gridiron junction boxes.
Surge
An instantaneous and usually brief increase in
voltage or electrical current in a circuit. This can
sometimes be detrimental to the integrity of a signal
or to electronic equipment.
Swivel Yoke
A semi-circular yoke with a slot running centrally
though most of its length to allow for the mounting of
luminaires at various angles.
In the theater industry, a curtain hung at the
top of a stage opening to make the opening of the
proscenium arch adjustable. In the film and video
industries, a set piece placed in front of a luminaire
to hide it from view of the camera.
Telescoping Stand
A height-adjustable stand that has two or more
concentric tubular sections, i.e.., risers, that slide
inside one another and lock into place.
Three Phase
A term for an alternating current electrical
supply that has three hot legs, with each leg at a
phase that is 120° apart from the other, with or
without a neutral leg.
A term used to describe something that requires
a three phase electrical supply to operate.
Threefer
A special power cord that has one male connector
electrically connected to three female connectors via
three separate cables or sets of sleeved wires.
Throw
To direct the light emanating from a luminaire
in a particular direction.
An abridged version of Throw Distance.
Throw Distance
The effective distance between a luminaire and the
area or subject to be illuminated.
Tie In
To connect the line side leads of power
distribution equipment, dimmer racks, etc., to the
primary electrical supply for a location, such as a
company switch, circuit breaker panel, or other piece
of power distribution. This is generally done with
feeder cables.
Tilt
To rotate up and down around a horizontal
axis.
Tint
A color low in saturation.
Top Hat
See the definition for Snoot.
Transmission
The ability of light to penetrate through
something.
Transmission Factor
The ability of a medium to allow for the
transmission of light, expressed as a percentage.
Trim
To finely adjust the height of battens,
curtains, or any item whose exact height is
critical.
To finely adjust the voltage output of some
electronic dimmer at the lowest control setting.
To finely adjust the focus, beam direction,
shutter positions, etc., for a group of luminaires set
up for a production.
Triple Header
A tee bar with three individual, or sets of, studs
or receivers.
Truss
A structure fabricated from various truss sections,
used to hold up luminaires, scenery, and/or other
production equipment. Truss can be ground-supported, or
suspended overhead with rigging.
Truss Section
A sturdy, lightweight support structure fabricated
from tubular aluminum in various shapes and sizes.
Truss Spot
A short throw follow spot operated from a truss
rig.
Twist-Lock Connector
A commonly used type of locking blade connector
that requires a twisting action to lock the mating
connectors together, manufactured by Harvey Hubbel,
Inc. The name "Twist-Lock" is trademarked.
Twofer
A special power cord that has one male connector
electrically connected to two female connectors via two
separate cables or sets of sleeved wires.
A "U" shaped clamp that attaches onto a pipe and
locks with the aid of a bolt, that when tightened,
bites into the pipe and locks the clamp in place. It
also has a secondary bolt for the attachment of
equipment of light-to-moderate weight.
UL
Abbreviation for Underwriters' Laboratories,
Inc.
Umbrella
An umbrella made from reflective fabric used for
bounce lighting.
Underwriters' Laboratories, Inc. (UL)
An independent, not-for-profit organization testing
for public safety. This organization Lists and Labels
products and materials and Recognizes parts,
components, and materials, and is acceptable to most
jurisdictional authorities, e. g., electrical
inspectors, fire marshals, insurance underwriters, and
governmental agencies.
Imaginary lines drawn from the highest seats of the
audience area, often in a balcony, and from the seats
in the front row, to the lowest hanging obstructions
over the stage to determine what portions of the
performing area will be visible to all of the
audience.
Voltage Potential (V)
Often considered to be the force of electrons
moving from one point to another. Technically not a
force at all, but the potential for electrons to move
from one point to another, as measured in volts.
A sturdy, U-shaped metal bracket that attaches to
opposite sides of a luminaire, or, video and film
industry reflectors, butterflies, etc., such that it
allows either to tilt freely. A locking mechanism is
provided to prevent slippage when the desired position
has been achieved. Also provided at the center of the
yoke is a hole, stud, or receiver for mounting the
yoke.
A compact striplight that uses 1 to 4 groups of ten
12 volt lamps wired in a series circuit, manufactured
by Altman Stage Lighting, Inc. The name Zip Strip is
trademarked.
Zoom
An abridged version of Zoom Focus.
A term used to describe a luminaire with such a
focus. Some ellipsoidal spotlights and many follow
spots have a zoom focus system.
Zoom Focus
A term used to describe an optical system whereby
the lenses in a luminaire adjust such that a beam
pattern with a hard edge can be attained at various
sizes at various distances without sacrificing beam
lumens.
