Stage lighting instrument

The housing may be designed with specific elements that help reduce heat and increase the efficiency of a lamp.

The first lantern to make use of die castings was the Strand Pattern 23 designed by Fred Bentham in 1953, this small mirror spot enjoyed a 30-year production run and found its way into many British schools, halls and theaters.

Each unit has a characteristic reflector, used in conjunction with the lens (or lack thereof) to create the desired effect.

Specially designed reflectors are able to absorb and dissipate infrared at the fixture before the visible light reaches the stage.

Combined, these two axis allow the fixture to point nearly anywhere in a spherical range of motion encircling the yoke.

Some yokes are motorized, allowing remote control systems to change where a fixture is pointing during a show.

C-Clamps are hook clamps that use a threaded bolt to attach to a pipe or batten and to hold the instrument secure.

Although they are far more efficient, they cannot be dimmed (run at less than full power) without using specialized dimmers, cannot dim to very low levels, 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.

The introduction of the LED allows much more variety of color and they also require much less power, making them useful to have in a theater or production.

[1] Conventional (non-intelligent) fixtures are designed to accept a number of different accessories intended to assist in the modification of the output.

Roundels can sustain heavy use for a long time without fading and are often found in more permanent installations.

The lamp and reflector remain a fixed unit inside the housing, and are moved forward and back to focus the light.

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 2 the Leko (short for Lekolite, from Strand lighting).

[22] The major components of an ERS light are the casing in which the internal parts are mounted, an ellipsoidal reflector located in the back of the casing(truncated conical ellipse), a lamp mounted to position the filament at the rear focal point of the ellipsoid, a dual plano-convex lens (two plano-convex lenses facing each other in the barrel), and at the front, a gel frame to hold the color gel.

The light from the lamp is efficiently gathered by the ellipsoidal reflector and sent forward through the gate, shutters and lens system.

An iris also can be inserted in this position to make the beam smaller in diameter, reducing the light cast without the sharp edges of the shutters.

The barrel sizes can range from a narrow, long distance 5- or 10-degree spot to a broad and short-distance 50- or even 90-degree.

The first 90-degree profile lantern was developed by Selecon Performance Lighting as part of their "Pacific" range of products.

This makes them more versatile, since a venue can purchase varying degrees of barrels without buying as many instruments.

This is no longer necessarily true, so most manufacturers now identify their fixtures by beam angle and light output.

The beam projector no longer is used to the extent that it once was, as newer fixtures and PAR lamps have created easier ways to produce the effect.

Follow spots are commonly used in musical theater and opera to highlight the stars of a performance, but may be used in dramas as well.

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.

Moving lights (or intelligent fixtures) began to gain widespread acceptance in the concert industry in the early 1980s.

As the digital age progressed, the cost of these fixtures reduced, and they are increasingly used in many major theatrical productions.

[citation needed] Their principal feature is the ability to remotely control the movement and characteristics of the output beam of light.

The majority of intelligent fixtures employ arc lamps as a light source, and therefore use a variety of mechanical methods to achieve the effect of dimming.

Mechanically, stepper motors connected to various internal optical devices (such as gobos and color wheels) manipulate the light before it escapes the fixture's front lens.

Oftentimes there will be encoder wheels which will control the Pan, Tilt, Focus, Zoom, Color, and Effects.