Ellipsoidal Reflector Spotlight Definition
|Back to Glossary Terms List|
|Also known as...
Ellipsoidal Reflector Spotlight - Description :
ERS is an acronym standing for Ellipsoidal Reflector Spotlight. These are sometimes known by their brand names, especially Leko, short for Lekolite, the name given to them by their inventors, Joseph Levy and Edward Kook. ETC's Source Four has become a very popular ERS throughout the industry, and some people use the term Source Four to refer to spotlights in general. They come in many forms, and are the most numerous and important instrument type in use. The flexibility of the ERS allows them to fulfill the bulk of the lighting roles in the theatre, from area lighting to close specials, from long throws from the back of the house to shin kickers on the stage.
ERS's may have more than one focusing lens, while all possess internal shutters for cropping the emitted light, and all accept a color gel in front of the lens and a gobo in front of the shutters. ERS's may have bulbs mounted axially, or with the base either up or down (it is important to hang a lamp in the proper orientation). The lenses are smooth and full, not stepped, and it is the lens or lenses that move in the ERS, not the bulb and reflector assembly as in the fresnel.
The ERS improves over the efficiency of the fresnel by surrounding the bulb in an ellipsoidal reflector, with the filament of the bulb at one focus and the aperture to the lens housing at the other. The shutters and gobo are ideally in focal point of this aperture. (In UK: the term ERS is not often used. An ERS is simply considered a very good profile.)