What is "opera glasses"

n. 1 (opera glass English) 2 One or more pairs of small low-powered binoculars for use at a theatrical performance

n. an optical instrument designed for simultaneous use by both eyes [syn: binocular, binoculars, field glasses]

Opera glasses, also known as theater binoculars or Galilean binoculars, are compact, low-power optical magnification devices, usually used at performance events, whose name is derived from traditional use at opera performances. Magnification power below 5× is usually desired in these circumstances in order to minimize image shake and maintain a large enough field of view. A magnification of 3× is normally recommended. The design of many modern opera glasses of the ornamental variety is based on the popular lorgnettes of the 19th century.

The London Opera Glass Company was founded in 1913 and provides opera glasses in many of London's West End theatres.