A Glossary of Lighting Terms

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Sometimes, the phrases, acronyms and strings of numbers or number-letter combinations used to talk about photographic lighting or techniques can be daunting to the uninitiated neophyte photographer. We've prepared a list of the basic terms. Have we left any out that you think should be added? Please let us know!

A

A

Abbreviation for Ampere or Amperage.

AC Voltage
Short for Alternating Current Voltage.

Accent Light
Used to draw extra attention to one section of the subject and add interest and sparkle.

Alternating Current Voltage
A voltage that undergoes cyclical changes in value and polarity, often represented as waves.

Ambient Light (Available Light)
The surrounding light exclusive of that being directed on a specific subject, usually non-directional.

American National Standards Institute (ANSI)
An independent industry-wide association that establishes standards to promote consistency and interchangeability among manufacturers.

Amp
Short for Ampere.

Amperage (A)
The measure of electrical current in amperes.

Ampere (A)
A unit of measurement for Electrical Current.

Angle of Light
The angle formed between the light-subject axis and camera-subject axis. Both horizontal (H) and vertical (V) should be specified.
Examples: Camera-top light about 0° H, 5° V; rim Light 180° H & V; key light commonly 15° to 45° H and V.

Anode
An electrode that is positively charged, i.e. the electrode toward which electrical current moves.

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.

Aperture

  1. The planar opening within the optical system of a light source that defines the total amount of usable light created by the optical system.
  2. A circular ring that attaches to the front of a snoot used in the film and video industries to alter the size and light center strength.

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.

B

Backdrop
A vertical surface with painted designs which is used to form the background for a theatrical setting, usually made of heavy cloth, sometimes drawn tight to achieve a smooth, flat surface, sometimes textured. It may also be used as a cyclorama.

Back Light
Used behind the subject and pointing toward the camera for visual separation of subject and background.

Background Light
Aimed at the background to create separation between subject and background.

Balance
Short for Color Balance.

Ballast
An electrical apparatus that limits the electrical current in a particular circuit, usually a circuit containing an arc source.

Barn Doors
An apparatus with adjustable flaps, usually 2, 4 or 8, that attaches to the front of a light source. It is used to block or shape the beam.

Beam
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 light sources, such as ellipsoidal spotlights and follow spots, can be adjusted or designed so 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 Diameter
The diameter of the base of a cone-shaped beam where the perimeter of the base is defined by where the intensity is 50% of the maximum intensity.

Boom
In the film and video industries, an adjustable arm mounted at an angle from a vertical pipe or stand, often counter-balanced, used to hold cameras, lighting or sound equipment.

Borosilicate Glass
A type of glass commonly used for lenses and mirrors.

Breakup
See Cucalorus.

Broad Light
A light unit with a wide beam spread.

Bulb
Quite often this term is used interchangeably with Lamp.

Butterfly
A large fabric scrim, diffuser, reflector or opaque fabric panel used for dimming, softening, bounce lighting and shading, respectively. A butterfly is usually 4' to 8' square and mounted on a yoke-supported frame.

C

Cable

  1. The insulated wire cords used to interconnect devices.
  2. A strong, flexible wire rope made of steel, used to support pipes, battens, trusses, etc., from an overhead structure.

Cam-lok™
A commonly used type of insulated, locking, single conductor cable connector manufactured by Crouse-Hinds Inc. The name Cam-lok™ is trademarked.

Capacitor
A component designed to have a specific amount of capacitance in an electrical circuit.

Casters  
Wheels placed on stands, trunnions, road cases or anything that requires easy mobility.

C-Clamp
In the film and video industries, a C-shaped device that can be affixed securely to a pipe and locks with the aid of a bolt, which when tightened, presses the clamp like a vise onto the pipe. It also has a stud or studs for the attachment of light sources, grip equipment, etc.

Celo
A plastic coated, wire-mesh cucalorus.

Century Stand (C-Stand)
A grip stand manufactured by Matthews Studio Equipment Corp. The name Century Stand is trademarked.

China Silk
A fabric used for linear diffusion material; it spreads the light linearly.

Chroma
In the video industry, a measure of color intensity; it describes the saturation of a hue.

Cine
Of or relating to the film and video industries.

Circuit Breaker
An automatically operated electrical OFF switch designed to protect an electrical circuit from damage caused by overload or short circuit. A circuit breaker can be reset once it switches off and stops electrical flow.

Color Balance
An arrangement of hue, chroma and value within a design that produces a sense of equilibrium, i.e., no single colored area commands attention to the detriment of the entire arrangement.

Color Correction
Adjusting the color temperatures of various light sources 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 (filters), but adjusting the input voltage levels is a method sometimes used for certain light sources.

Color Frame
An apparatus used to hold color media or other types of filters. It can be of various shapes and sizes and may be composed of one or more pieces.

Color Temperature
A linear scale for measuring the color of ambient light with warm (yellow) light measured in lower numbers and cool (blue) light measured in higher numbers. Measured in terms of “degrees Kelvin,”* daylight  is approximately 5600-degrees Kelvin, a candle is approximately 800 degrees, an incandescent lamp is approximately 2800 degrees, a photoflood lamp is 3200 to 3400 degrees, and a midday blue sky is approaches 10,000-degrees Kelvin.

*Named for engineer and physicist Lord Kelvin (William Thomson), who conceived of the thermodynamic temperature scale, in 1848.

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 light source with relative ease.

Conductor
Generally, anything that will carry electrical current, but usually refers to an insulated wire.

Connector

  1. Specifically, the name for a family of electrical wiring devices, such as plugs and receptacles, composed of one or more contacts; a means for electrically attaching a conductor to each contact; a means for electrically insulating each contact from the other; 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. Any item used to make an electrical connection between two or more separate conductors.

Contrast Ratio
Compare two reflected-light readings:

  1. The lightest significant area of the subject or scene, versus
  2. The darkest. Each medium or method of reproduction has different brightness ratio limits. Projected films about 125:1 (seven stops); Video about 32:1 (five stops). See Lighting Ratio.

Convection Cooling
A cooling process whereby air circulation is maintained in order to transfer heat from an object to the atmosphere around it by supplying adequate ventilation or heat sinks without the use of electrical or mechanical items such as fans, blowers, etc.

Convex
A term used to describe a lens side that is outwardly and usually spherically curved.

Cookie (Cooky)
Short for Cucalorus.

Cool Light
Light having a color temperature of approximately 3600°K to 4900°K, i.e., bright-white to blue-white.

Crank-Up Stand
A stand that is raised and lowered with the aid of a rotating handle and gear mechanism.

Crown Glass
A type of glass that has excellent optical quality, used for lenses and mirrors.

C-Stand
Short for Century Stand.

Cucalorus
An opaque or translucent material having one or more cutouts that will allow light to pass through in order to project a dappled form or pattern, such as the suggestion of the shadows of tree branches, on the subject and background.

Cuke (Cukes)
Short for Cucalorus.

Current
Short for Electrical Current.

Cutter
A narrow, rectangular flag, ranging from 18" to 72" in length, and 6" to 24" in width, generally used to block only a portion of the light beam.

Cyc
Short for Cyclorama.

Cyc Light
Short for Cyclorama Light.

Cyclorama (Cyc)
A vertical surface which is used to form the background for a theatrical set that is usually made of heavy cloth drawn tight to achieve a smooth, flat surface, or left loose and textured. It is meant to suggest limitless visual 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 light source mounted at the top or bottom of a cyclorama in order to light it in a smooth, uniform manner.

D

Daisy Chain

  1. A control signal wiring system employed in the interconnection of a plurality of some electronic items, such that the first item’s output connector is connected to a second item’s input connector via a control cable. A third item is connected to the second in the same manner, and so on until all items have been connected. The control console is connected to the input connector of the first item only, but sends data to all items via the interconnecting control cables. Some items that can sometimes be daisy chained are color scrollers, automated light sources and dimmer racks or packs.
  2. See Feed Through.

Daylight
Light that has a color temperature of approximately 5500-5600°K, which has been approximated to be the color temperature of ordinary sunlight at midday under normal atmospheric conditions.

Daylight Filter
A filter used to balance light from a warmer source, so that the spectral distribution will approximate daylight, i.e., 5500-5600°K.

DC
Abbreviation for Direct Current.

DC Voltage
Short for Direct Current Voltage.

Dichroic
A type of metallic coating applied to glass and some other materials that allow 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 or stippled surface that is moderately reflective.

Diffuse Light
Soft, generally even illumination.

Diffuser

  1. Generally, something made of diffusion material that softens the quality of the light passing through it to produce a more flattering light with less noticeable shadows.
  2. In the film and video industries, a fabric panel, used for diffusing, with the light source being a light source or sunlight. They are available in a variety of sizes, shapes and materials of varying textures and opacities.

Diffusion
Short for Diffusion Material or Diffusion Media.

Diffusion Frame
An apparatus used to hold diffusion material. It can be configured of various shapes and sizes, and may be composed of 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
A term used to describe the use of binary code to record information that has been reduced to numerical form; usually instructional information in regard to control consoles.

Digital Multiplex (DMX)
A system that simultaneously transmits more than one digital signal.

Dim
To change the intensity of a light source.

Dimmer
An apparatus used to control the intensity of a light source.

Dimmer Pack
A portable housing that contains a group of electronic dimmers, usually not less than 4 nor more than 24. Some dimmer packs are designed for permanent installation.

Dimmer Panel
An apparatus, usually 19" long, that contains a group of electronic dimmers that are installed into a dimmer rack.

Diode
A solid-state rectifier.

Direct Current (DC)
An electrical current that maintains constant direction. Batteries provide DC current.

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 light source in a straight line to the subject or area.

Distribution
Short for Light Distribution.

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.

Dot
A small, round scrim, diffuser, reflector, or gobo, placed close to a light source, used for dimming, softening, bounce lighting or casting shadows, respectively. They are usually 3" to 10" in diameter.

Double-Ended Lamp
A somewhat elongated lamp that has a base and contact on each end.

Duvetyn (Duvatyne, Duvetine, Duvetyne, Duvyteen)
A smooth, lustrous, velvety opaque fabric used for butterflies, cutters, flags, gobos and overheads in the film and video industries.

E

Ears
The three individual slots that function as the color frame holder found on the front of some light sources. They are often used to retain other items, such as color wheels, barn doors, etc.

Edison Connector
The standard household male, parallel-blade plug that may or may not have a ground pin.

Edison Lamp Holder
The standard household screw-in lamp socket that accepts medium screw type lamp bases.

Egg Crate
A square or rectangular grid that, when installed on large open face light sources, alters the shape and intensity of the light and reduces glare.

Electrical Current 
The flow of electrons from one point to another, measured in Amperes.

Electrical Frequency
The cycles per second of alternating current, measured in Hertz. In North America, and parts of South America and Southeast Asia, the frequency is 60Hz. The rest of the world operates on a frequency of 50Hz.

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 Power
The rate at which electricity is delivered to a circuit, in watts, or in reference to magnetic transformers, in Volt-Amperes.

Electronic Ballast
A ballast uses electronic components to limit electrical current. This type of ballast is often referred to as a flicker-free ballast.

Ellipsoidal
Short for Ellipsoidal Spotlight.

Ellipsoidal Spotlight
A spotlight that is encased in an ellipse-shaped reflector and framing shutters, and sometimes an iris and pattern slot.

Eye Light
A small, intense light source used to front light a subject, usually a person’s face, with hard light.

F

Fahrenheit
A graduated scale used to measure temperature. In the Fahrenheit scale, the freezing point is 32°F and the boiling point is 212°F.

Falloff
A term used to describe the illuminated area just outside of the field. (This term may also refer to the illumination in this area.) Light from a point source falls off inversely to the square of the distance. Move the light from 10' away to 20' away, and you have 1/4 of the intensity; 40', 1/16th. Diffused lights fall off even faster than point sources. See Inverse Square Law.

fc
Abbreviation for Foot-candle.

Feed Through
A wiring system employed in some electrical equipment and light sources in which the line-side leads or flush-mount connector(s) for a first item branch into two circuits internally. One circuit provides the electrical supply to the item itself, and the second circuit exits the unit by means of a set of load-side leads or another flush-mount connector(s). This allows for a second item to be electrically connected to the first. A plurality of items may be connected in this way, usually light sources such as strip lights. See Daisy Chain.

Female
A term applied to a connector that contains the holes or slots for receiving the pins, prongs, blades or tabs of a male connector. The female connector should always be attached to the line side of a circuit.

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
Angled from the side opposite the key light, this light softens the shadows created by the key and evens out the lighting ratio.

Filter
A term that refers to color media, diffusion material, light blocking or neutral density.

Filter Frame
See Color Frame.

Finger
A small, narrow, rectangular scrim, diffuser, reflector, or gobo, placed close to a light source, used for dimming, softening, bounce lighting, and casting shadows, respectively. Fingers are usually 2" to 6" in length, and 12" to 14" in width.

FL
A lamp designation that means “flood.”

Flag (Filter, Gobo)
An opaque panel, usually made of fabric, placed in the beam of a light source to block a portion of the beam or the whole beam. It can also hide lights in the dark recesses of a scene. They are usually square or slightly rectangular in shape, ranging from 10" to 48" in length, and 12" to 48" in width. Which term you use depends upon the device’s size and what part of the country you are in.

Flash

A tube filled with xenon gas through which an electrical charge of high voltage is passed to create an electrical arc that emits a short, bright flash of light. Flash light is daylight balanced, usually measuring 5500° Kelvin. See Strobe.

Flat Light
See Diffuse Light. All light is characterless, textureless and shallow shadowed when the source is close to the camera. Soft light is, by its nature, flatter than hard light, but even a soft source, above or to the subject’s side, is not flat.

Flicker
The flashing of some light sources 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.

Flood

  1. The position of a moveable 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 light source consisting of a rectangular lamp and sometimes a single lens, used to direct a large amount of light on a relatively large area.

Floppy Flag
A large flag that is designed to fold in half and function as a cutter or smaller flag.

Fluorescence
The property of certain materials to absorb radiation of certain wavelengths, usually ultraviolet, and re-emit the radiation as light.

Fluorescent Lights

Cool and daylight balanced, fluorescent lights have become very popular for photographic and video capture. Fluorescent lighting can be used in the form of screw-in bulbs and reflectors, or rectangular banks of lights.

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.

Focus
To aim and adjust a light source to give the beam its desired size (spot or flood), edge (soft or hard), field (even or peak) and shape (round, patterned or cut).

Focus Lens
A movable lens in a multi-lens optical system that adjusts the focus of a light source.

Follow Spot
A narrow-beam focusing instrument that is manually operated and is usually composed of a powerful light source, an iris, shutters, a color changer and 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-candle (fc)
A non-metric unit of measurement for Illumination, i.e., 1 lumen per square foot.

Framing Projector
A spotlight that has framing shutters or barn doors.

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 light sources, but extensively in ellipsoidal spotlights, usually four (top, bottom, right and left); follow spots, usually two (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.

French Flag
A small metal flag, usually used for shading.

Fresnel
Short for Fresnel Spotlight.

Fresnel Lens
Named for its inventor, French physicist Augustin J. Fresnel, and developed around 1800 for lighthouses, this is a flat lens consisting of concentric rings on one side that are segments of the spherical portion of a plano-convex lens. The other side is flat, i.e., plano. It controls light in the same manner as a plano-convex lens, which converges light into a beam. Many light sources employing this type of lens have a stippled pattern on the flat side of the lens to diffuse to smooth out the beam.

Fresnel Spotlight
A spotlight employing a single fresnel lens that produces a soft-edged beam, usually provided with a spherical reflector and a means to adjust the focus from spot to flood.

F/Stop
A rating often applied to scrims used in the film and video industries on their 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.

Fuse
An electrical device designed to stop the flow of electricity automatically when a predetermined overcurrent tries to pass through it. This is meant to prevent further damage or fire from overheating.

Fused Quartz
A relatively pure, high-temperature glass used to manufacture lamp envelopes. It has a melting point of approximately 1650° C.

G

Gaffer
The lighting technician who is in charge of the electrical aspects of a set or production.

Gaffer Grip
A large, spring-loaded clamp with serrated or rubber-cushioned jaws. It usually has a stud or studs for the attachment of luminaries and grip equipment.

Gaffer’s Pole
See Operating Pole.

Gag
An apparatus composed of two grip heads attached to each other via a common bolt.

Gel (Gelatin, Media)

As used with photographic lights, a strong, flexible, fade-resistant material, used to change the color, amount or quality of light.

Guide Number
Guide numbers are used as a rating system to gauge the power or range of flash. The guide number equals the distance x f/stop. For example, say your flash has a guide number of 80’. At ISO 100, to determine the proper exposure for a subject 20 feet away, multiply 20 by X number (in this case 4) to get 80 (the guide number). Setting the aperture to f/4 (80 = 20 × 4) will render a proper exposure (at ISO 100). 

H

Hair Light
Light source aimed at a subject’s hair to create separation from the background and add sparkle and highlights.

Halation
The distortion that appears around the edge of a sharply focused beam pattern. This effect can be reduced with the aid of a donut.

Half Scrim
A metal scrim whose screen occupies one half of its frame so that the straight edge of the screen is located across the diameter of the frame. It is used to cut light output.

Halogen
The name for a family of gases, used in lamps, to maintain proper color temperature.

Hard Edge
A beam pattern edge that is very clear and distinguishable, i.e., one without a fuzzy or blurry perimeter.

Hard Light

  1. Illumination that has a hard edge and produces sharply defined shadows. Often this light is very intense, but generally less flattering than soft light.
  2. A light source 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 light source 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.
  5. Short for Grip Head or Ball Head.

Hertz
A unit of measurement for the Frequency of alternating current, i.e., one cycle per second.

Highboy (Hiboy)
A heavy-duty stand designed to hold light sources or heavy grip equipment. The stand is equipped with wheels and tall risers, and usually a 1 and 1/8" receiver and a grip head.

High Key
A lighting style in which the majority of the scene is highly illuminated, usually enhanced by bright costumes and sets. A low ratio of key plus fill light lowers the contrast, helping to obtain this effect.

Hollywood Box
A piece of power distribution equipment used in the film and video industries, composed of a metal housing, a means for connecting an electrical supply and female flush-mount connectors or bus bars that can be electrically connected with bus bar lugs, for the purpose of supplying electricity to light sources. Some are also provided with overcurrent protection.

Hot Lights
Common term for continuous light sources, especially tungsten or halogen lights that run hot.

Hot Restrike
A term applied to an igniter that can hot-start an arc lamp.

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.

Hot Start
A term used to describe the ignition of a heated arc lamp, i.e. a lamp that has just been electrified.

HMI
Abbreviation for Hydrargyrum (Greek for Mercury) Medium-Arc Lodides. This is a commonly used type of metal halide lamp manufactured by Osram-Sylvania Corp. The term Osram HMI is trademarked.

Hz
Abbreviation for Hertz.

I

Illumination

  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 foot candles or lux.

Incandescent
A term used to describe a lamp, or a light source that utilizes such a lamp, that employs the incandescence of a filament as its light source. The filament is housed in a vacuum; enough electricity is passed through the filament that it glows. 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.

Infrared (IR)

  1. A reference to anything that uses or emits infrared radiation.
  2. Electromagnetic radiation having a wavelength longer than visible red light but shorter than microwaves, i.e., approximately 750nm to 1mm.

Inky
A small fresnel spotlight with a 1.5" to 3" lens diameter, usually 100-250 watts.

Inky Dink
See Inky.

Instant Restart
See Hot Restrike.

Instant Restrike
See Hot Restrike.

Intensity (Light Output)
The “strength” of the incident light source, independent of the subject’s reflectivity.

Inverse Square Law
The quantity of light is inversely proportional to the square of its distance, i.e., illumination (fc) = Intensity (cd) / Distance2 (ft2).

Say a light is placed 1 foot away from the subject. If the distance is doubled to two feet, the square of its distance is (22) or 2 x 2 = 4. The inverse of 4 is ¼. Therefore, the quantity of light falling on the subject from 2 feet will be ¼ the amount of light falling on the subject from the original 1 foot. If the light is moved to a distance of 8 feet, the square of its distance is (82) or 8 x 8 = 64. The inverse of 64 is 1/64. The quantity of light on the subject from 8 feet will be 1/64 the amount of light that falls on the subject from 1 foot away. Each time you roughly increase the distance incrementally, you open up your aperture two, three, four stops, etc., to compensate for the light falloff.

Iodide
A halogen gas used in lamps to maintain proper color temperature.

IR
Abbreviation for Infrared.

Iris
Short for 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.

K

  1. Abbreviation for Kelvin.
  2. Short for Kilowatt in the theater, film and video industries.

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. The Kelvin scale is used to gauge color temperature.

Key Light (Main Light)
The principle source of light which establishes the character of the lighting, including atmosphere and mood. It may suggest a source, like the sun, or a window.

Key Grip
The supervising grip on a production; the person ultimately responsible for all other grips and grip equipment.

Kicker
A sideline, low angle back light that adds a slight edge light to the side of the subject.

Kilowatt (kW)
1000 watts.

L

Lamp

  1. Any light source in a self-contained package composed of an envelope (containing gas, filaments, etc.), filament or electrodes, base, contacts, gas and any support structures. The source can be of the incandescent, fluorescent, quartz halogen, LED or arc type.
  2. Quite often this term is used interchangeably with light source.

Lamp Base
The part of a lamp to which the electrical connections are made; the part with the contacts. It is often the mechanical support or heat sink for the lamp.

Lavender
A type of material used for fabric scrims.

Leko
A commonly used term for an ellipsoidal spotlight. Named after its inventors Joseph Levy and Edward Kook, the names Leko and Lekolite are trademarked by Strand Lighting Corporation.

Leads
The electric cable(s) or sleeved, insulated wires, attached to a light source or piece of power distribution equipment, that terminate in a connector for the purpose of providing an electrical connection to the electrical supply or to another light source.

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.

Light

  1. Illumination; the aspect of radiant energy of which a human observer is aware through a visual sense. Its electromagnetic radiation has a wavelength longer than ultraviolet radiation but shorter than infrared radiation, i.e., approximately 380mm (violet) to 750mm (red).
  2. A term that is often used interchangeably with light source.

Light Distribution
The way in which illumination of any color or quantity is spread over a particular background.

Lighting Ratio
The percentage of key light to fill light. Optimum and maximum lighting ratios depend upon subject matter, mood, media and type of reproduction, as well as personal tastes. In television a timid ratio is 2:1 (twice as much key as fill), a dramatic one, 8:1 (eight times as much key as fill, popular for film-noir look); a maximum one, about 16:1. Also called Brightness Ratio.

Light Meter
An apparatus used to measure various quantities of light such as color temperature, foot candles, lux, flash, etc.

Light Source
Anything that emits light, such as an arc or a filament, a lamp or light head, bulb or flash.

Light Spill
A general term used to describe any stray light, including light leaks.

Location Fresnel
A fresnel spotlight used primarily in non-standard production settings such as 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 light source that has an effective intensity at a relatively long distance. This term is very subjective and dependent on the type of light source used.

Louver
An opening provided with one or more slanted fixed or movable fins to control the angle of light, like venetian blinds for lighting.

Lowboy (Loboy)
A heavy-duty stand designed to hold light sources or heavy grip equipment. The stand is equipped with wheels and short risers, and a 1 and 1/8" receiver and a grip head.

Low Key
A lighting style in which the majority of the scene is scarcely illuminated, usually enhanced by shadows and dark costumes and sets. A high ratio of key light to fill light increases the contrast, helping to obtain this effect.

Lumen
A unit of measurement for Luminous Flux, a measure of the total "amount" of visible light emitted by a source.

Luminous Flux
The rate of flow of light energy evaluated, in Lumens, with reference to visual sensation; the part of the total energy radiated per unit time from a luminous source that is capable of producing the sensation of sight.

Lux
A metric unit of measurement for Illumination, e.g. 1 lumen per square meter.

M

Main Light
See Key Light.

Magnetic
A term used to describe an apparatus that utilizes a magnetic field to function.

Magnetic Ballast
A ballast that uses a magnetic field to limit electrical current. These types of ballasts generally do not prevent flicker.

Magnetic Transformer
A transformer that uses a magnetic field to convert voltage from one value to another. Simple common magnetic transformers consist of two wire coils wrapped around an iron core, each winding having its own pair of leads, one pair for the application of an input voltage, and the other pair for the output voltage.

Male
A term applied to a connector that contains the pins, prongs, blades, 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.

Mercury Vapor Lamp
An arc lamp whose gas is primarily mercury vapor.

Metal Halide Lamp
An arc lamp that uses mercury vapor combined with metal halides, that when heated, radiates light with a color temperature of approximately 5500°K.

MFL
A lamp designation that means medium flood.

Modeling Light
A continuous burning light in the center of a flash unit used to preview the location of the illumination and shadows from the flash burst.

Mogul Base
A lamp base that falls in the larger range of sizes for the type of base in question, i.e., approximately 1 and 1/2" diameter for screw and pre-focus type bases, approximately 1 and 1/2" post-to-post distance for bi-post bases and approximately 1 and 1/6" prong-to-prong distance for end prong and extended end prong bases.

Muslin
A material used for fabric scrims used in the theater, film and video industries. Also used in the manufacturing of backgrounds.

MR Lamp
Originally, this designation meant a lamp with a small, integral, multi-faceted reflector, but has since come to designate a lamp with a small, integral, mirrored reflector. The reflector could be parabolic or ellipsoidal.

Mylar
A type of plastic that can withstand fairly high temperatures and is used in the manufacture color media.

N

Nanometer (nm)
A unit of measurement commonly used for wavelengths of light, equal to 1/1,000,000,000 meters.

Neutral Density Filter
A filter that reduces the intensity of light without affecting its color.

NFL
A lamp designation that means narrow flood.

Noise
Short for Electrical Noise.

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.

NSP
A lamp designation that means narrow spot.

O

Open Face
A term used to describe the light sources that use no lenses.

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, light sources, pantographs, etc.

Overhead
A large scrim, diffuser, reflector, or opaque fabric panel, used for dimming, softening, bounce lighting and shading, respectively, with the light source being a lamp or sunlight. They are usually 12' to 40' square and mounted on stand supported frames.

P

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 parabola.

PAR Can
A generally lightweight light source that uses a PAR lamp, or in some cases, ray light reflector kit. The light beam characteristics depend on the type of lamp used.

PAR Lamp
A designation for a lamp with a parabolic aluminized reflector.

PAR Light
A generally lightweight light source that utilizes a PAR lamp. The beam characteristics depend on the type of PAR lamp used.

Pattern
A very thin, heat-resistant metal plate with a pattern 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 as the light shines through the cutouts.

Pattern Holder
A metal frame with a knob used to place patterns into the pattern slot of a light source.

Pattern Rotator
A motorized pattern holder that spins the pattern.

Photometric
A term used to describe anything that involves the measurement of light.

Photometric Data
Measurements of light and its properties.

Photometrics
Short for Photometric Data.

Photometry
The science of measuring light and its properties.

Pigeon
A small metal plate with nail holes and a 5/8" stud attached.

Pigtail
The relatively short electric cable, power cord, or leads on a light source 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 Spot
A spotlight that has an extremely narrow beam.

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 light sources, distribution equipment, etc.

Plano
A term used to describe a lens side that is perfectly flat.

Plano-Convex Lens
A lens that is flat on one side and convex on the other. These lenses focus light rays passing through them into a beam.

Polarizing Filters
Polarizing camera filters can be set to reduce most glare, as well as darken blue skies.
Best camera angle: 90° to the source light. Light loss: approximately two stops.

Pole Cat
In the film and video industries, a spring loaded, adjustable cross bar that when placed between a pair of walls or structures, allows for the attachment of lightweight light sources or grip equipment.

Pole-Op
Short for Pole-Operated.

Pole-Operated
A term used to describe a light source, yoke, pantograph, or other apparatus that can be controlled via an operating pole.

Pot
Short for Potentiometer.

Potentiometer (Pot)
An electrical component that has the ability to vary the resistance in an electrical circuit. It always has a means for adjustment, such as a knob or handle, to make your light source brighter or dimmer.

Pyrex™
A type of borosilicate glass that can withstand very high temperatures, used for lenses and mirrors. Manufactured by Corning Glass Co., the name Pyrex™ is trademarked.

Q

Quartz
Short for Fused Quartz.

Quartz-Halogen
See Tungsten-Halogen.

Quartz-Iodine
A term used to describe a family of tungsten-halogen lamps that use the halogen gas iodine and an envelope made of quartz in their manufacture.

R

Reflector

  1. Generally, anything that causes reflection.
  2. A metal or glass apparatus, usually curved in some manner, used in most light sources 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 light source or sunlight. They are available in a variety of sizes and shapes and materials of varying reflectance.

Reflector Board
A reflector for the film and video industries made out of a solid, lightweight, metallic coated material. One side is usually mirror-like for hard light reflection, and the other side is diffused for bounce lighting.

Refraction
The bending of electromagnetic radiation, such as light or heat, as it passes obliquely from one medium to another of different density.

Reporter Light
A compact, lightweight, handheld floodlight often used in conjunction with video cameras and often powered by batteries for portability.

Rim Light

  1. Back light that usually refers to illuminating objects.
  2. A light source that provides such illumination.

Rocky Mountain Leg
A height adjustable leg on a stand, usually a grip stand.

S

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, 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 Screen
A metal wire screen, placed at the front of an open-face light source, designed to retain large pieces of broken glass should the lamp break.

Sail
The total surface area of an overhead, butterfly, scrim, flag or cutter.

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, like deep red. Low saturation is one with a large amount of white light added to the color, such as light pink.

Scoop
Named for its scoop-like shape, an open face flood light with a large, diffuse reflector that is essentially the body of the light source. 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

  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 lamp head or sunlight. They are available in 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 light source to act as a dimmer. They are also available so that only half of the frame is screened, therefore allowing for only a portion of the light to be dimmed. For us, a metal screen used in front of a light to reduce intensity without diffusion.

Scrim Set
A set of metal scrims comprising a full double density, half double density, full single density and half single density.

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.

Shutter Blade
A single framing shutter.

Shutters

  1. Short for 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 Light

  1. Illumination of a subject from the side to place the subject in depth.
  2. A light source that provides such illumination.

Silk

  1. Specifically, a fabric used for linear diffusion material; it spreads the light linearly. It can be made from natural China silk or nylon.
  2. Generally, a scrim used in the film and video industries that is made from silk.

Single Ended Lamp
A lamp that has only one base and all of its contacts on the base.

Snoot
A cone-shaped accessory that mounts on the light to confine the beam to a very small spot.

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 light source that provides such illumination.

Solid
An opaque panel, usually made of fabric, placed into the beam of a light source to block a portion or all of the beam.

SP
A lamp designation that means spot.

Specular
A term used to describe a surface that is highly reflective or mirror-like; the kind of hard light from a small, pinpoint light source.

Specular Light
See Hard Light, definition #1.

Spot

  1. Short for Spot Light.
  2. The position of a focusable lamp, lens or pair of lenses on a spotlight that produces the most narrow field angle.
  3. To mark a location on which a light source will be focused.
  4. A term used to describe a round light pattern.

Spot Light
Generally, any of several types of light sources 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.

Spun Glass
A diffusion material made from glass fibers.

Stand Adapter
An apparatus used for mounting any one of a number of devices to a stand.

Strip Light
A multi-lamp light source with its lamps mounted in a straight row.

Strobe
Short for Strobelight. See Flash.

Strobe Light (Flash)
A tube filled with xenon gas through which an electrical charge of high voltage is passed to create an electrical arc that emits a short, bright flash of light. Flash light is daylight balanced, usually measuring 5500° Kelvin. See Flash.

Stud

  1. A metal protrusion, generally 3/8", 1/2", 5/8" or 1 1/8" in diameter. It is used to mount light sources and assorted grip equipment to a receiver such as a light stand. Studs also have wide, circular grooves designed to captivate the tip of the tee-handle or bolt provided with the receiver. This prevents the receiver-stud combination from unintentionally uncoupling, and can also prevent the stud from rotating once it’s seated.
  2. Any threaded metal protrusion used to mount light sources and assorted grip equipment via a nut or threaded socket.

Studio Fresnel
A fresnel spotlight used primarily in studios for the film and video industries. Because portability is generally not a concern, these tend to be larger than location fresnels of the same wattage.

T

Three-Point Lighting
The standard lighting system of key, fill and back lighting from which all other lighting setups evolve.

Transformer (Xformer)
An item that converts voltage from one value to another. There are two basic types, electronic and magnetic, and both come in many configurations.

Translucent
A term used to describe something that transmits light, but scatters light rays so that a clear image cannot be seen through the material.

Transparent
A term used to describe something that transmits light without scattering light rays, so that a clear image can be seen through the material.

Tungsten
An element used to manufacture lamp filaments. It has a melting point of approximately 3400°.

Tungsten-Halogen
A term used to describe a family of lamps that use the halogen gas iodine, an envelope made of quartz, and a filament made of tungsten, in their manufacture.

Tweenie
A 300-650 watt fresnel spotlight.

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.

Two-Pin Base
A lamp base with two narrow, parallel pin shaped contacts protruding from the bottom.

U

Ultraviolet (UV)

  1. A reference to anything that uses or emits ultraviolet radiation.
  2. Electromagnetic radiation having a wavelength longer than x-rays but shorter than violet light, approximately 40nm to 380nm.

Ultraviolet Light (UV Light)
Although not actually light, this is a commonly used term for Ultraviolet Radiation.

Ultraviolet Radiation (UV Radiation)
Invisible electromagnetic energy, of which the longer wavelengths are used to excite fluorescent materials. The wavelengths below 320nm are potentially harmful to human tissue.

Umbrella
An umbrella made from reflective fabric used for bounce lighting. Some translucent umbrellas with removable black covers are able to pass light through and diffuse it.

Unit
A term that is often used interchangeably with light source.

UV
Short for Ultraviolet.

V

Volt (V)
A unit of measurement for voltage.

Voltage (V)
The measure of voltage potential, in volts.

W

Warm Color
Generally, a color that is in the yellow-orange-red range.

Warm Light
Light having a color temperature of approximately 2600°K - 3400°K, or yellow-white to red-white.

Wash
An even overall illumination covering a large area.

Wash Light
A light source used to produce a wash.

Watt (W)
A unit of measurement for heat or electrical power.

Wavelength
The distance, measured in the direction of propagation, of a repetitive electromagnetic wave between two successive points.

X

Xenon
A gas used in some arc lamps that allows for a point source with extremely high luminous intensity and a color temperature of approximately 5500-6200°K.

Y

Y Cable
See Twofer.  

Z

Zoom
Short for zoom 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 light source adjust so that a beam pattern with a hard edge can be attained at various sizes at various distances without sacrificing beam lumens.

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This seems to be more about selling equipment than lighting.  Your definition of broad, short and butterfly are about equipment and the definition of each is the the most important part of portrait lighting.