Editing Stage lighting (section)

=== Lighting instruments ===
[[Image:ETC Source 4s at marine corps museum 1.JPG|thumb|right|[[Source Four]]s in use at the United States Marine Corps Museum]]
{{Main|Stage lighting instrument}}
In the context of lighting design, a lighting instrument (also called a ''luminaire'' or ''lantern'') is a device that produces controlled lighting as part of the effects a [[lighting designer]] brings to a show.  The term ''lighting instrument'' is preferred to ''light'' to avoid confusion between light and light sources.

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{{snd}}a metal or plastic container to house the whole instrument and prevent light from spilling in unwanted directions.
* Light source ([[lamp (electrical component)|lamp]]).
* Lens or opening{{snd}}the gap in the housing where the light is intended to come out.
* Reflector{{snd}}behind or around the light source in such a way as to direct more light towards the lens or opening.
Additional features will vary depending on the exact type of fixture.

Most theatrical [[light bulb]]s (or ''lamps'', the term usually preferred) are tungsten-halogen (or quartz-halogen), an improvement on the original incandescent design that uses a halogen gas instead of an inert gas to increase lamp life and output.  Fluorescent lights are infrequently used other than as [[worklight]]s because, although they are far more efficient, they are expensive to make ''dimmed'' (run at less than full power) without using specialised dimmer [[Electrical ballast|ballasts]] and only very expensive models will dim to very low levels. They also do not produce light from a single point or easily concentrated area, and usually have a warm-up period, during which they emit no light or do so intermittently.<ref name="Crabtree">[https://books.google.com/books?id=Ueo5gYK9CwgC] Scenic Art for the Theatre by Susan Crabtree and Peter Beudert.</ref>  However, fluorescent lights are being used more and more for special effects lighting in theaters. [[High-intensity discharge lamp]]s (or HID lamps), however, are now common where a very bright light output is required—for example in large follow spots, [[hydrargyrum medium-arc iodide]] (HMI) floods, and modern automated fixtures.<ref name="Interior Graphic Standards">[https://books.google.com/books?id=ROlG3CTGzYQC] Interior Graphic Standards by Corky Binggeli and Patricia Greichen p. 558</ref>  When dimming is required, it is done by mechanical dousers or shutters, as these types of lamps also cannot be electrically dimmed.

Over the last six years, LED-based luminaires of all varieties and types have been introduced to the market.  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.

[[File:E190ww-LDI-1.jpg|thumb|Ovation E-190WW LED ellipsoidal spots (ERS) hanging on 20.5" truss.]]

Most instruments are suspended or supported by a U-shaped ''yoke'', or '[[trunnion]] arm' fixed to the sides of the instrument, normally near its [[center of gravity]]. On the end of such, a clamp (known as a hook-clamp, C-clamp, or pipe clamp—pipe referring to [[batten (theater)|battens]]) is normally fixed, made in a "C" configuration with a screw to lock the instrument onto the pipe or batten from which it is typically hung. Once secured, the fixture can be panned and tilted using tension adjustment knobs on the yoke and clamp. An adjustable c-wrench, ratchet (US) or spanner (UK) is often used to assist the [[Theatrical Technician|technician]] in adjusting the fixture.<ref name="Stage Lighting Primer">[http://www.stagelightingprimer.com/index.html?slfs-right-frame.html&2] Stage Lighting Primer</ref>

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 {{convert|100|lb|kg|abbr=on}} 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. Many venues place strict guidelines regarding the use of safety cables.<ref name="saftey rules">[http://www.conncoll.edu/offices/ehs/9134.htm Connecticut College Theater Services Hazard Communication Guide] {{Webarchive|url=https://web.archive.org/web/20100527170605/http://www.conncoll.edu/offices/ehs/9134.htm |date=2010-05-27 }}, Please see 'Lights' section.</ref>

The entire lighting apparatus includes the lights themselves, the physical structure which supports them, the cabling, control systems, [[dimmer]]s, power supplies, and the [[light board]]s. (lighting console)

Hanging the [[light]]s or hanging the battons to hang the lights is known as 'rigging'.