Opera 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 of binoculars at opera performances. A magnification power below 5× is usually desired for such use (vis-à-vis, for example, birding) both to minimize image shake and to 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.