Lighting instruments Definition

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Lighting instruments - Description : 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 another... * Box/Housing - a metal or plastic container to house the whole instrument and prevent light from spilling in un-wanted directions. * Source of light (bulb or 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 lense or opening. Additional features will vary depend on the exact type of light. Most theatrical light bulbs (or lamps, the term usually preferred) are incandescent. Fluorescent lights are rarely used outside of work lights because, although they are far more efficient, they cannot be 'dimmed' (run at less than full power), they do not produce light from a 'point' or easily concentrated area, and have a warm-up period, during which they emit no light or do so intermittently. Until recently (1990s), carbon arc lamps were common in high power follow spots. Carbon arc follow spots have been largely replaced by high-intensity xenon or tungsten-halogen instruments. Smaller, self-contained arc lamps are used in many modern automated fixtures. All lights are either floodlights or spotlights. The distinction has nothing to do with the area covered, but is based on the presence or absence of a focusing lens or lenses. Lamps that lack a focusing lens, or are in a permanent fixed relationship to their lens, are floodlights. Please Note: In the UK the nomenclature is slightly different to the USA version (above paragraph). Although there is some adoption of the USA naming conventions it has been normal to catagorize lanterns by their lens type, so that a spotlight is known as a profile in the UK, a floodlight is either a fresnel, a PC (Pebble/Plano/Prism Convex), or a floodlight (a linear bulb with a reflector and no lense). Spotlight in the UK normally refers to a followspot. The following definitions are from a USA point of view, and would be confusing when used, without further clarification, in the UK.