Stage lighting instrument

A stage lighting instrument, also called a luminaire or, in British usage, a lantern, is a device that produces and directs light for theatre, concerts and other live performance. Instruments differ mainly in how they shape light: some simply flood an area, some blur a beam's edge for blending, and some focus it sharply enough to project a pattern.^[1]

The main families are the flood, the Fresnel, the profile (which includes the ellipsoidal reflector spotlight), the PAR can, the followspot and the automated "moving" light. Their light sources changed over time from candles and limelight to electric arcs, incandescent lamps, tungsten halogen lamps, high intensity discharge lamps and, more recently, LEDs.^[2:1]

Types of instrument

The descriptions of floods, Fresnels, profiles, PAR cans and followspots in this section follow the lantern reference by Jon Primrose on Theatrecrafts unless another source is shown.^[1]

Flood

A flood is the simplest type: a lamp and a reflector in a box with no lens. It offers no control over the beam, so it is used mainly to light scenery and cloths, and for working lights, rather than to light performers.^[1:1]

Fresnel

The Fresnel lantern takes its name from the French physicist Augustin-Jean Fresnel (1788–1827), who devised the stepped lens. Its lens has concentric steps on the front and a pebbled back. The lantern was first used in stage lighting in the late 1920s, and it gives more control over beam angle than a flood but less than a profile.^[1:2] Four hinged flaps called barndoors can trim the beam.^[1]

A related design, the pebble convex (or prism convex) lantern, uses a flat-backed lens with a pebbled surface that gives a soft edge slightly harder than a Fresnel's. It is common in Europe and rare in the United States.^[1]

Profile and ellipsoidal reflector spotlight

A profile lantern has a lens (sometimes two), a lamp, a reflector, shutters and a gate, which is the opening between lamp and lens where the beam is shaped. It is named for its ability to project the outline of anything placed in the gate.^[1:3] Metal or glass stencils called gobos can be placed there to project patterns, logos or images, and an iris can narrow the beam.^[3]

The most common profile is the ellipsoidal reflector spotlight (ERS). It places the lamp at one focus of an elliptical mirror, so that light leaving the lamp is reflected through the mirror's other focus, where the gate sits. Four framing shutters at the gate shape the beam.^[3:1] Older units were named by lens diameter and focal length, such as 6x9 or 6x12, while modern units are classed by beam angle: 36, 26, 19, 10 and 5 degrees.^[3]

The nickname "Leko" comes from the surnames of Joseph Levy and Edward Kook of Century Lighting, whose LekoLight was a trademark in 1932, and the name became so widely used that all ERS instruments were for decades called Lekos.^[3:1] Theatrecrafts instead says the Leko was "originally patented in 1933."^[1] These dates may refer to different events (a trademark and a patent), but the sources do not say, so the exact origin remains unresolved. Patent and trademark records would likely settle it.

In 1992 Electronic Theatre Controls (ETC) introduced the Source Four,^[3:1] an ellipsoidal profile that uses a 575 W lamp. Entertec (David Cunningham and Greg Esakoff) designed it and ETC manufactures it.^[1:4]

PAR can

A PAR can is a simple housing, the "can," that holds a PAR (parabolic aluminised reflector) lamp. The lamp is a sealed unit that combines lamp, reflector and lens. The PAR can came into use in the late 1960s in the rock and roll industry and was introduced in the UK by the hire company ESP in 1968.^[1:5] Its beam is oval and can be rotated by turning the lamp. It suits strong colours and effects, but Theatrecrafts describes it as unsuitable for general wash lighting except in music or comedy venues.^[1]

Followspot

A followspot is a special profile lantern with extra handles, sights, a built-in colour changer and iris. It is usually much higher in power than other profiles and is mounted on a stand rather than a standard bar, so an operator can track a performer.^[1:4]

Automated and moving lights

An automated luminaire adds motors and remote control to an instrument. The first commercially deployed example was Vari-Lite's VL1. The idea came from a fall 1980 remark by Jack Maxson, a partner in the sound company Showco: "Add two more motors and it moves." The VL1 premiered on September 25, 1981, in Barcelona on Genesis's ABACAB tour. It had three colour wheels and one gobo wheel giving 60 colour combinations, along with pan, tilt and dimming.^[4:1]

The growth of automated lighting in the 1980s coincided with rapid growth in the use of high intensity discharge lamps in entertainment fixtures.^[2]

Light sources

The light source inside an instrument has changed several times, and each change altered what instruments could do.

• Candles and oil lamps. Early theatres used tallow candles, crude oil lamps, torches and hanging lamps. In 1638 Nicola Sabbatini proposed a dimming system that lowered metal cylinders over candles.^[5:1]
• Gas. The Chestnut Street Theatre in Philadelphia became the first fully gaslighted theatre in 1816.^[5:1]
• Limelight and arcs. Limelight heats a block of lime until it glows bright white; it was used in entertainment from the late 1830s.^[2] The carbon arc followed: the earliest electrical entertainment illumination appeared at the Paris Opera in 1846.^[2]
• Incandescent lamps. England's Savoy Theatre became the first completely electric theatre in 1881.^[5:1] By the 1880s incandescent light had replaced gas and limelight in theatres.^[2:1]
• Tungsten halogen. Lamps using iodine or bromine were adopted in the mid-1960s.^[2:1]
• High intensity discharge. Use grew rapidly in the 1980s, alongside automated lighting.^[2:1]
• LED. LED-based stage luminaires appeared on stages worldwide from around 2008.^[2:1]

Conflicting dates

The two history sources give different dates for the same technologies. The course timeline from Northern Virginia Community College dates Henry Drummond's limelight to 1803 and Sir Humphry Davy's electric arc to 1809,^[5:1] while HARMAN's history gives the late 1830s for limelight and 1846 for the arc at the Paris Opera.^[2:1] The sources may be dating different events, the invention of each light and its first theatrical use, but neither says so. Dated primary records, such as playbills or contemporary accounts of Drummond's and Davy's work, would settle the question.