We are providing a glossary of terms. If
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Glossary of Theatrical Lighting Terminology
ABCDEFGHIJKLMNOPQRSTUVWXYZ
Accent Light: 1) Illumination
used to make something stand out. It may be done with intensity and/or
color. 2) A luminaries 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.
Backlight: 1) Illumination
on a subject from behind, causing a separation of the subject from the
background, often creating a fringe of light around the subject. 2) 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: 1) A group of luminaires. 2)
A group of dimmers or dimmer modules. 3) 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: 1) An abridged version of Lens
barrel. 2) A male turn-around, generally used for the connection of control
cables.
Base: 1) The bottom of a stand used
for mounting luminaires. 2) 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. 3) 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: 1) Generally, the conoid, or
in some cases, the pyramoid of light emanating from a lumina ire. 2) 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.
Blacklight: A luminaire with a beam
whose wavelengths are too short to be visible, i.e., 320 to 380nm. 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: 1) The melting of a lamp filament.
2) 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.
Cable: 1) A rope of
wire used to transmit electricity or data. 2) To run, hook up, and/or
interconnect electrical cables and the items to which the cables are connected.
3) 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: 1) The removable or hinged, rear
cover of some luminaires that contains the lamp socket and power cord.
2) See definition #2 for Base.
Carbon Arc: An arc source in which
the arc is formed in air between a pair of carbon electrodes.
Card: 1) In general, a circuit board.
2) 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.
C-Clamp: 1) See definition for Pipe
clamp. 2) 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/studs
for the attachment of luminaire, grip equipment, etc.
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: 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 nonautomatic means and to open
the circuit automatically on a predetermined overcurrent 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.
Colorine: lamp dip (yum yum! <crunnnnnch>)
Color Medium: Any colored transparent
material that can 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.
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: 1) 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. 2) 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: 1) 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. 2) 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: 1) A loop made of rope attached
to a yoke for the purpose of supporting excess coils of electric cable.
2) 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: 1) 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. 2) 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 crosslighting.
Crosslighting: Illumination from two
sources on opposite sides of the subject.
C-Stand: see Century Stand
Cue (Q): 1) An event in a production
that is the signal for a specific action. 2) The signal given in order
to cause such an action. 3) 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: 1) To remove illumination from
a scene or subject. 2) To block a portion of a light beam.
Cutoff: A general term for anything
used to block a portion of a light beam, e.g., flags, cutters,shutters,
barn doors, etc.
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.
Cyc: see Cyclorama
Cyc Light: See Cyclorama Light
Cyclorama (Cyc): 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.
D/A Converter: Digital-to-Analog
Converter
Data Sheet: see Cut Sheet.
Daylight: 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: 1) To scatter light using
diffusion material. 2) A term used to describe a somewhat dull and/or
stippled surface that is moderately reflective.
Diffuser: 1) Generally, something made
of diffusion material. 2) 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: 1) To change the intensity of
a luminaire. 2) 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: 1) 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-Per-Circuit: A situation or
design where each electronic dimmer used in a theater or studio affects
only one circuit.
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.
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: 1) A single flap on a Barndoor.
2) 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: 1) Downward illumination,
almost perpendicular with the floor. 2) 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.
Edison Connector:
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 it's 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: 1) An abridged version of
Electrics Pipe. 2) 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: 1) Generally, one versed
in the field of electricity and its application. 2) 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 ellipsoidal.
Ellipsoidal Spotlight: A spotlight
that embodies an ellipsoidal reflector and framing shutters, and sometimes
an iris and pattern slot.
Ellipsoidal Reflector Spotlight (ERS):
See Ellipsoidal Spotlight.
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.
Extension Hanger: A telescoping grip
hanger.
Eye: The fresnel lens of a fresnel
spotlight.
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.
Fader: An item found on most control
consoles, such as a slider, used to fade.
Fade-To-Black: To gradually decrease
the intensity of all lighting to a blackout.
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: 1) Supplementary illumination
used to reduce shadows, preventing them from appearing black. 2) 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: 1) The borderlight and/or
its position on the first electric. 2) 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: 1) The position of a movable
lamp, lens, or pair of lenses on a spotlight that produces the widest
field angle. 2) 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 Trunion): 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.
Flyrail: 1) 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.
2) In older theaters, the flyrail is a pinrail.
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.
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: 1) 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). 2) 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.
Focusing Instrument: A luminaire whose
beam can be adjusted from spot focus to flood focus.
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.
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: 1) The speed at which something
pulses or cycles. 2) 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: 1) Illumination from the
general direction of the viewer(s). 2) 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: 1) 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. 2) A type of colorless diffusion
material made of glass fibers or high-temperature plastic.
F/Stop: 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.
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.
Gaffer: 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: 1) An abridged but commonly used
version of Gelatin. 2) To place gelatine in front of a luminaire to alter
the color of the beam.
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.
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.
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: 1) 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.
2) Any error in the execution of a cue from a control console.
Gobo: 1) See definition for Pattern.
2) 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.
Go Button: A button on a control console
that executes a cue.
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: 1) The wood or metal framework
located in the flies that supports the pulleys containing the steel wires
or rope holding up scenery, battens, etc. 2) The metal structure of pipes
in a studio ceiling for the purpose of hanging luminaires, power distribution
equipment, or grip equipment. 3) 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: 1) A term used by professional
film and video industry lighting people to refer to someone utilizing
grip equipment and other related items. 2) 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.
Grounded: To have a conducting connection
to ground.
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.
Half Scrim: 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: 1) Illumination that has
a hard edge and produces sharply defined shadows. Often this light is
very intense. 2) A luminaire that provides such illumination.
Head: 1) A general term for a fresnel
spotlight. 2) The part of a follow spot that contains the light source,
i.e., not the stand, ballast, or interconnect cable. 3) The part of a
metal halide luminaire that contains the lamp, i.e., not the ballast or
interconnect cable. 4) 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.
Ignite: To cause an
arc to form across the electrodes of a light source, either manually,
as with carbon arc sources, or by using an igniter, as with arc lamps.
Illumination (E): 1) Generally, a term
for light or lighting. 2) In photometry, the amount of light, i.e., luminous
flux per unit area incident on a surface, in Footcandles or Lux.
Image: 1) The actual design of a pattern.
2) 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 the definition
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.
Kelvin (K): 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.
Kilo (k): A numerical prefix denoting
1000.
Kilovolt (kV): 1000 volts.
Kilovolt-Ampere (kVA): 1000 volt-amperes.
Kilowatt (kW): 1000 watts.
Lamp: 1) 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. 2) Quite often this
term is used interchangeably with Luminaire, especially in the theater
industry. 3) 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: 1) A single thin, heat-resistant
metal plate from an iris or some mechanical dimmers. 2) 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
Lekolight 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: 1) The movable, inner
tube of a focusing lens system in an ellipsoidal spotlight. 2) The complete
tubular front section of an ellipsoidal spotlight that contains the lenses.
Lens Holder: 1) Any apparatus used
to retain a lens. 2) See definitions #1 and #2 for Lens Barrel.
Lens Size: 1) 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. 2) Generally, the diameter
of a lens.
Level: 1) An abridged version of Light
Level. 2) 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: 1) Illumination, i.e., the aspect
of radiant energy of which a human observer is aware through the visual
sense. Its electromagnetic radiation has a wavelength longer than ultraviolet
radiation but shorter than infrared radiation, i.e., approximately 380nm
(violet) to 750 nm(red). 2) 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.
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.
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 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: 1) One trained
in the lighting skills and techniques necessary for the implementation
of the lighting design for a particular production. 2) 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: 1) The maximum electrical
load that something, such as wire, fuses, electrical connectors, etc.,
can safely accommodate. 2) 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.
Main Light: See the
definition for Key Light.
Male: 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: 1) 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. 2) 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. (A good movie)
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-toprong 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.
Near Cyc: A cyclorama
light placed close to the cyclorama, general less than 8'.
NEMA: Abbreviation for National Electrical
Manufacturers' Association.
NEMA Configuration: An alpha-numeric
code applied to connectors to guarantee consistency and interchangeability
among manufacturers.
Neutral: 1) The connection point in
a data or wye system that is earth grounded, or electrically connected
to an item that serves in place of the earth. 2) A term used to describe
any point on a neutral conductor. 3) An abridged version of Neutral Conductor.
4) Without color.
Neutral Conductor: A current carrying
conductor that is electrically connected to neutral.
Neutral Density Filter: A filter that
reduces the intensity of light without affecting its color.
Non-Dim: 1) A term used to describe
a circuit that does not pass through a dimmer. 2) A term used to describe
a load that is not intended to be connected to a dimmer.
Offstage: Out of sight
from the audience.
Ohm: 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.
Pan: To rotate from
side to side around a vertical axis.
Panel: 1) A general term that can refer
to an overhead, butterfly, or large framed scrim, diffuser, or reflector.
2) 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.
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.
Par Can: See the definition for Par
Light.
Par Lamp: See the definition for Par
Light.
PAR-Lamp: A designation for a type
of lamp. In the case, one with a parabolic aluminized reflector.
Par Light: A generally lightweight
luminaire that utilizes a PAR lamp. The beam characteristics depend on
the type of PAR lamp used.
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.
Pattern Holder: 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.
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: 1) A thin prong used as a contact
on some male connectors and lamp bases.
Pin-Beam Spotlight: See the definition
of Pinspot.
Pin Connector: 1) 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. 2) A type of insulated, single conductor cable
connector used in the film and video industries.
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: 1) A long, hollow, cylindrical
bar made from iron for strength, used for battens, booms, gridirons, etc.
2) 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: 1) An abridged version of Stage
Pocket, Floor Pocket, or Wall Pocket. 2) 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: 1) An abridged version of Scene
Preset. 2) 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.
Quad-Box: 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.
Quartz: An abridged version of Fused
Quartz.
Rack: 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: 1) Generally, anything that
caused reflection. 2) 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. 3) 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: 1) The time it takes
for a dimmer to reach its intended level from the initiation of an input
control signal. 2) the time it takes a lamp filament to react to a change
in voltage.
Rig: 1) 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. 2) 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: 1) 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. 2) Flat platforms of various sizes, usually portable, used for supporting
luminaires or other production equipment, or sometimes used as portable
stages. 3) 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.
Runway Lights: Footlights that are
used on stage runways.
Safety Cable: 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, an 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: 1) 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. 2) 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: 1) 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. 2) 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 it's 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 and acts as the second
contact.
Scrim: 1) 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. 2) 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. 3) 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: 1) 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.
2) 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: 1) An abridged version of
Framing Shutters. 2) 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: 1) 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. 2) 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: 1) 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. 2) A term used to describe something that requires a single
phase electrical supply to operate. Slider: 1) A small, linear potentiometer
often used as a setting adjuster on a control console. 2) 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: 1) Derived from "Sockett",
see the definition for Lampholder 2) A female connector. 3) A hollow,
cylindrical shaped mounting item used to accept studs, generally equipped
with a teehandle 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. 4) A relay holding device that
comprises terminals for making electrical connections to the socket, and
contacts that make the electrical connections to the relay. 5) A miniature
hole with two internal contacts on a diode pin matrix for the insertion
and electrical connection of diode pins. 6) In general, any threaded,
round opening. 7) 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: 1) Illumination that produces
shadows with a soft edge. 2) A luminaire that provides such illumination.
Soft Patch: A term used to describe
a patch system where by 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: 1) 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. 2) 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: 1) Generally, any connector
that is electrically connected to two or more other connectors, all constructed
as a single unit. 2) 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.
Stagehand: One trained in the physical
skills and techniques necessary for the implementation of a stage production.
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: 1) A male pin connector.
2) A male slip connector.
Stage Pocket: 1) 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. 2) In the film and video industry, a female slip connector.
Stage Right: The right side of the
stage when facing the audience.
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: 1) See the definition for Ignite.
2) 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: 1) 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. 2) An abridged version of Strobe Light.
Strobe Light: A luminaire specifically
designed to create a strobe effect, 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.
Teaser: 1) In the
theater industry, a curtain hung at the top of a stage opening to make
the opening of the proscenium arch adjustable. 2) 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.
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.
Three Phase: 1) 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. 2) A term used to describe something that requires a three phase
electrical supply to operate.
Throw: 1) To direct the light emanating
from a luminaire in a particular direction. 2) 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: 1) To finely adjust the height
of battens, curtains, or any item whose exact height is critical. 2) To
finely adjust the voltage output of some electronic dimmer at the lowest
control setting. 3) 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.
U-Clamp: 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.
Variable Lens System:
See definition #1 for Zoom.
Vertical Sight Lines: 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.
Wall Box: See the
definition for Wall Pocket.
Wall Bracket: A sturdy metal arm that
attaches to a wall and provides a means for attaching a luminaire.
Wall Pocket: A stage pocket whose cover
is flush mounted with the wall to which it is mounted.
Warm Color: Generally, a color that
is in the yellow-orange-red range.
Wash: 1) An even, overall illumination
over a large area. 2) To create such an illumination.
Wash Light: A luminaire used to produce
a wash.
Watt (W): A unit of measurement for
heat or Electrical Power.
Wattage (W): The measure of electrical
power in watts.
Wavelength: The distance, measured
in the direction of propagation, of a repetitive electromagnetic wave
between two successive points.
Wing: 1) See definition #1 for Door.
2) The areas to the left and right of the stage or performing area not
visible to the audience.
Yoke: 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.
Zip Strip: 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: 1) An abridged version of Zoom
Focus. 2) 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.