Stage lighting instrument
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- "Floodlights" redirects here. For Floodlights in sport, see Floodlights (sport).
Stage lighting instruments are used in stage lighting to illuminate theatrical productions, rock concerts and other performances taking place in live performance venues. They are also used to light television studios and sound stages. A lighting instrument is different from “light” in much the same way that a musical instrument is different from “music”.
Terminology is different between the USA and UK for many stagecraft terms. In the USA, lighting fixtures are called "instruments" in the UK, they are called "lanterns" or "luminaires". This article mainly uses terms common to the USA.
Lighting instruments can be broadly separated into two categories: floodlights, which illuminate a wide area, and spotlights, which produce a narrower, more controllable light beam. The distinction has to do with the degree to which one is able to control the shape and quality of the light produced by the instrument, with spotlights being controllable, sometimes to an extremely precise degree, and floodlights being completely uncontrollable. Instruments that fall somewhere in the middle of the spectrum can be classified as either a spot or a flood, depending on the type of instrument and how it is used. In general, spotlights have lenses while floodlights are lensless, although this is not always the case.
There are a variety of instruments frequently used in the theater. Although they vary in many ways they all have the following four basic components in one form or other:
- Box/Housing - a metal or plastic container to house the whole instrument and prevent light from spilling in unwanted directions.
- Light Source (lamp).
- Lens or opening - the gap in the housing where the light is intended to come out.
- Reflector - behind or around the light source in such a way as to direct more light towards the lens or opening.
Additional features will depend on the exact type of fixture.
Most theatrical light bulbs (or lamps, the term usually preferred in the US) are Tungsten-Halogen (or Quartz-Halogen), an improvement on the original incandescent design that uses halogen gas instead of an inert gas to increase lamp life and output. Fluorescent lights are rarely used other than as work lights (see below) because, although they are far more efficient, they cannot be dimmed (run at less than full power) without using specialized dimmers and they will not dim to very low levels. They also do not produce light from a single point or easily concentrated area and have a warm-up period, during which they emit no light or do so intermittently. High-intensity discharge lamps (or HID lamps), however, are now common where a very bright light output is required - for example in large follow spots, HMI (Hydrargyrum medium-arc iodide) floods, and modern automated fixtures. When dimming is required, it is done by mechanical dousers or shutters, as these types of lamps cannot be electrically dimmed.
Most instruments are suspended or supported by a "U" shaped yoke, fixed to the sides of the instrument, normally near its center of gravity. In North America, the yoke is connected to the pipe or batten from which the instrument is hung by a C-clamp, which utilizes a threaded bolt to prevent the clamp falling off the bar and also to prevent the clamp from moving. In Europe, a hook clamp is used. The shape of the hook clamp prevents it from falling off; the bolt justs stops the clamp from moving. Once secured, the fixture can be panned and tilted using tension adjustment knobs on the yoke and clamp.
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[edit] Floodlights
[edit] PAR lights
Parabolic Aluminized Reflector lights, or PAR lights, or Parcans , are used when a substantial amount of flat lighting is required for a scene. Some PAR lights resemble a car headlight, in that they possess a faceted lens, an integral part of the lamp, whose position relative to the filament cannot be altered. Others have a clear or pebbled lens. PAR lights have seen heavy use in rock and roll shows, especially those with smaller budgets. They are often used in combination with smoke or haze machines which make the path of the beam visible. They are also often used as top or side lights in the theatre and for special effects.
The lamp produces an intense oval pool of light with fixed focus and soft edges. The only way to adjust the orientation of the oval is to rotate the lamp/lens within its casing by grasping the backside of the lamp/lens or electrical connector.
The "number" associated with a PAR light (e.g: Par 64, Par 36, Par 16) indicates the diameter of the lamp in 8ths of an inch.[1]
In 1995 Electronic Theatre Controls (ETC) introduced the Source Four PAR as an alternative to Par lights[2][3] . The Source Four PAR uses a lamp separate from the lens and reflector assemblies.
[edit] Strip lights
Strip lights, also known as cyclorama or (Cyc) lights (thus referred to because they are good for lighting the cyclorama, a curtain at the back of the stage), battens or by the brand name codas, are long housings typically containing multiple lamps arranged along the length of the instrument and emitting light perpendicular to its length. Lamps are often covered with individual gels of multiple colors (often Red, Green, and Blue, which allow almost any color to be "dialed up") with each color controlled by a separate electrical circuit. Many striplights use round pieces of glass (called roundels) rather than plastic gels for color. Roundels can sustain heavy use for a long time and are often found in more permanent installations. Varying the intensity of the different colors enables the lighting designer to establish mood or time of day.
See also: Cyclorama (theater)
[edit] Scoop lights
Scoop lights or scoops are circular fixtures that do not have any lenses. They have a reflector at the back of the fixture that directs the light out of the fixture. Since they do not have any sort of lens system they are cheaper than other fixtures. However, the downside of this is that the light cannot be focused at all (even PARs allow more control than scoops). Scoops are most often used to flood the stage with light from above. Scoops can have gels affixed. Occasionally they are used as worklights. (the lights that are turned on during non-tech rehearsals, for the actors to work in.)
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[edit] House lights and work lights
House lights are incandescent or fluorescent floodlights. House lights provide light for the audience before and after performances and during intermissions. Work lights provide general lighting backstage, or in the house. House lights are often controlled by dimmers, but are sometimes on simple switches. Work lights are almost always switched only. House and work lights are usually off during performances but are occasionally included in the lighting design to establish focus or emphasize plot elements. It should be noted that when the house lights are not on a dimmer, the switch is usually under the control of the stage manager.
[edit] Spotlights
A spotlight is general term for any lighting instrument used in theatre to create a pool of light on the stage. There are many different types of spotlight which break down into three general areas:
- Fresnel lanterns or Fresnels (US) are small fixtures giving a soft-edged spot or pool of light. Their name comes from the distinctive ridged Fresnel lens used on the front
- "Profile spots (UK)" or Ellipsoidal Reflector Spotlights (US) tend to be longer fixtures containing convex lenses and having a gate at their focal point which enables the insertion of gobos or irises to shape the beam of light. They give a hard edged beam most often associated in the public mind with 'spotlights'. Large versions are operated by a technician as a 'followspot' to pick out performers on the stage.
- Pebble Convex lanterns (or "PCs") are similar to Fresnels, but use a plano-convex lens with a pebbled effect on the planar (flat) side, resulting in less "spill" outside the main beam. They are used much more widely in Europe than North America.[4]
[edit] Fresnel lantern
A Fresnel lantern (UK), or simply Fresnel(US), employs a Fresnel lens to wash light over an area of the stage. The lens is named after French physicist Augustin-Jean Fresnel, and consequently pronounced with a silent "s". The distinctive lens has a 'stepped' appearance instead of the 'full' or 'smooth' appearance of those used in other lanterns. (it was actually built this way so that lighthouses could through lights farther) The resulting beam of light is wide and soft-edged, creating soft shadows, and is commonly used for back light and side light. Another method of controlling the spread of light is to use either a snoot (also referred to as a top hat), which generally limits the light coming out, or a barn door, which allows you to work the flaps as though they were levers on an ERS. (shown on the right) These methods limit light output and keep excess light from spilling into the eyes of audience members.
A fresnel may also be used to produce an effect called a godspot, which directs light straight down.
Fresnels use a spherical reflector, with the lamp at the focus. The lamp and reflector remain a fixed unit inside the housing, and are moved back and forth to focus the light. This is done by a slider on the bottom or side of the lantern, or by a worm track. At very tight focus, the lanterns are the least efficient, as the least light can escape the housing. Therefore fresnels are not good for tight focus on small areas. They are most often used at medium distances from the stage for area lighting.
Recently, ETC introduced a new lighting fixture, the Source Four PARNel, which joined the ideas of the PAR fixture and that of Fresnels. The fixture is more versatile, allowing for a flood or a softer spot.[2]
[edit] ERS
The Ellipsoidal Reflector Spotlight or ERS is the most abundant and (arguably) important instrument type currently in theatrical use. The flexibility of the ERS allows it to fulfill the bulk of lighting roles in the theatre, from broad area lighting to tight specials; from long throws from the back of the auditorium to shin kickers on the stage. They are sometimes known as a Profile Spotlight (in Europe) or by their brand names, especially the Source Four (a popular lantern from ETC) and the Leko (short for Lekolite, from Strand lighting)[5].
ERS or profile lanterns can have many useful features. One of the most useful is the use of metal shutters at the focal plane of the lens to shape the beam of light. The shape of the beam is round but with the use of the shutters one can limit the beam to avoid walls, pipes in the lighting grid, or the front seats of the audience. Another feature is a gate, again in the focal plane for sliding in metal plates. These metal plates, commonly known as gobos or deckles, can have patterns cut into them, much like a stencil. These patterns are projected onto the stage. An iris can be also be inserted in this position to make the beam smaller in diameter, reducing the light cast without the sharp edges of the shutters. ERS instruments from ETC, Altman, Selecon and a variety of others have interchangeable barrels which can both create a very sharp or very soft beam as well as alter the beam degree, which can range from a narrow, long distance 19-degree spot to a broad and short-distance 50-degree or even 90-degree. The first 90-degree profile lantern was developed by Selecon Performance Lighting as part of their "Pacific" range of products. Since its introduction many other manufacturers have introduced their own 90-degree barrels.[6] The Selecon Pacific ERS is another innovative ERS. It has an irregular shape, which is because it is designed to reflect light off of a dichroic cold mirror, which has a heat sink to draw heat out of the instrument. This improves shutter, gobo and color gel life, and also can improve the temperature on stage.[7]
In the UK and Australia, the term ERS is not often used. Instead, an ERS is is known by its brand name, or called a "profile spot" (after its ability to project the silhouette or profile of anything put in the gate).
[edit] Followspot
The followspot (also called a trackspot) is a lighting instrument that is moved, by an operator or by DMX control, to emphasize or provide extra illumination and usually to 'follow' a specific performer, especially when he or she is moving around the stage. When most people use the term "spotlight" they are referring to the follow spot. Follow spots are commonly used in musical theatre and opera to highlight the stars of a performance, but might find use in a drama to briefly focus the audience's attention on a hand-motion or a prop; such as in a murder mystery or thriller. They are also used in sports venues, as well as many other applications.
These lighting instruments come in a variety of sizes with light sources ranging from low power incandescent light bulbs to very powerful xenon arc lamps. Carbon arc lamp spots were common until the 1990s, using the arc between carbon rods as their light source. These follow spots required special installations that include high volume ventilation due to the hazardous fumes produced by the carbon arc. The current generation, xenon, has extremely high internal pressure in the lamp and thus has its own safety concerns.
Followspots contain a variety of optic mechanisms including mechanical shutters, which allow the light to be doused without turning off the lamp, lenses to control beam width, and internal color gels. An interesting feature of the color gels is that on some you can throw in two or more at once, and therefore there's some possible color mixing.
[edit] Intelligent lights
Moving lights or Intelligent fixtures began to gain widespread acceptance in the concert industry in the early 1980's. As the digital age progressed, the cost of these fixtures reduced, and they are currently used in almost all major theatrical productions.
Their principal feature is the ability to remotely control the movement and characteristics of the output beam of light. This is achieved by either moving a mirror which reflects the beam, or by moving the entire fixture, which can pan and tilt by means of a motorized yoke. Usually they also contain other controls to shape, texture and color the light, such as gobo wheels. This ability to precisely, and repeatably set the position of the fixture allows one light to perform many functions, lighting multiple different areas in different ways. They can also move 'live' (i.e. while on), to achieve many of the spectacular effects used in modern productions.
The majority employ arc lamps as a light source (with the notable exception of several products by Vari-Lite), and therefore use a variety of mechanical methods to achieve the effect of dimming. Mechanically, stepper motors connected to various internal optical devices manipulate the light before it escapes the fixture's front lens.
Moving light programs are often much more complex than that of stationary instruments, requiring use of special Lighting Consoles and programs to set up. Typically this draws on a WYSIWYG (what you see is what you get) virtual program that allows designers to select lights by location rather than channel number.
Intelligent lights are used heavily in very large shows, like events in stadiums, where it is very difficult to reach lighting trusses for manual focusing. Although the fixtures may not be moved during the run of the show, they are focused remotely.
Intelligent lights can be controlled from the lightboard, with the use of some dials and a trackball; you can change their color, pattern, and several other features.
[edit] References
- ^ "Par Cans", Prefect's WPI Technical Theatre handbook, October 2006.
- ^ a b "Source Four History", Electronic Theatre Controls, October 2006.
- ^ Gillette, J. Michael (November 10, 2004). Theatrical Design and Production: An Introduction to Scene Design and Construction, Lighting, Sound, Costume, and Makeup. McGraw Hill, 362. ISBN 0072562625.
- ^ Theatrecrafts.co.uk - types of lantern. Retrieved 22 Oct 2006.
- ^ "Source Four", Electronic Theatre Controls, October 2006.
- ^ Gillette, J. Michael (November 10, 2004). Theatrical Design and Production: An Introduction to Scene Design and Construction, Lighting, Sound, Costume, and Makeup. McGraw Hill, 365. ISBN 0072562625.
- ^ Gillette, J. Michael (November 10, 2004). Theatrical Design and Production: An Introduction to Scene Design and Construction, Lighting, Sound, Costume, and Makeup. McGraw Hill, 365. ISBN 0072562625.
