Optical instrument for providing a magnified view of distant objects, consisting of two similar telescopes , one for each eye, mounted on a single frame.
In most binoculars, each telescope has two prisms , which reinvert the inverted image provided by the eyepiece of each telescope. Light rays travel along a folded path inside the telescopes, so the instrument has a shorter overall length. The prisms also provide better depth perception at greater distances, by allowing the two objectives (object lenses ) to be set farther apart than the eyepieces. Binocular eyepieces are often fitted to microscopes or other optical instruments.