Stage lighting

The personnel needed to install, operate, and control the equipment also cross over into these different areas of "stage lighting" applications.

They would build their theatres facing east to west so that in the afternoon they could perform plays and have the natural sunlight hit the actors, but not those seated in the orchestra.

Natural light continued to be utilized when playhouses were built with a large circular opening at the top of the theater.

At an unknown date, candlelight was introduced which brought more developments to theatrical lighting across Europe.

While Oliver Cromwell was ruling Britain, all stage production was suspended in 1642 and no advancements were made to English theaters.

Candles needed frequent trimming and relighting regardless of what was happening on-stage because "they dripped hot grease on both the audience and actors".

Commercial theaters tended to be more "conservative in their lighting, for economic reasons" and therefore used "candle-burning chandeliers" primarily.

Gas lighting hit the English stage in the early 1800s beginning with the Drury Lane and Covent Garden theaters.

In this type of illumination, a gas flame is used to heat a cylinder of quicklime (calcium oxide).

There is a modern movement that states that the lighting design helps to create the environment in which the action takes place while supporting the style of the piece.

The intensity of a luminaire (lighting instrument or fixture) depends on a number of factors including its lamp power, the design of the instrument (and its efficiency), optical obstructions such as color gels or mechanical filters, the distance to the area to be lit and the beam or field angle of the fixture, the color and material to be lit, and the relative contrasts to other regions of illumination.

[7] A tungsten lamp's color is typically controlled by inserting one or more gels (filters) into its optical path.

In the simplest case, a single gel is inserted into the optical path to produce light of the same color.

Gobos, or templates, come in many shapes, but often include leaves, waves, stars and similar patterns.

These fixtures and the more traditional follow spots add direction and motion to the relevant characteristics of light.

Scanners have a body which contains the lamp, circuit boards, transformer, and effects (color, gobo, iris etc.)

Scanners are typically faster and less costly than moving head units but have a narrower range of movement.

[13][14] An alternative formulation is by Jody Briggs, who calls them Variable of Light: Angle, Color, Intensity, Distance, Texture, Edge-quality, Size, and Shape.

The light plot is typically a plan view of the theatre where the performance will take place, with every luminaire marked.

Practical experience is required to know the effective use of different lighting instruments and color in creating a design.

Some of these fixtures have become very popular, whereas others have not been able to match the output from incandescent and discharge sources that lighting designers prefer.

LED fixtures are making a positive impact on the lighting market, and are becoming more popular when compared to the energy usage of current incandescent, halogen, and discharge sources.

[19] Most venues require an additional metal safety cable or chain to be attached between the fixture and its truss, or other string support anchorage.

Some larger fixtures can weigh over 100 lb (45 kg) and are suspended very high above performers heads, and could cause serious injury or death if they fell by accident or due to incorrect attachment.

In the event of failure, the cable would halt the fall of the fixture before it could cause serious damage or injury.

[21] In North American English, a bubble refers to the protrusion that occurs when one's body (or other oily substance) contacts the lamp.

Controllers are commonly lighting consoles designed for sophisticated control over very large numbers of dimmers or luminaires, but may be simpler devices which play back stored sequences of lighting states with minimal user interfaces.

The lighting controller is connected to the dimmers (or directly to automated luminaires) using a control cable or wireless link (e.g. DMX512) or network, allowing the dimmers which are bulky, hot and sometimes noisy, to be positioned away from the stage and audience and allowing automated luminaires to be positioned wherever necessary.

Such a loss of control might cause a dimmer to dim a circuit and thus potentially damage its non-dimming device.

Some automated lights have built-in dimming and so are connected directly to the control cable or network and are independent of external dimmers.