prism binoculars [2]

Optical instrument made up of two identical telescopes, one for each eye; it magnifies both near and distant objects.

body

Cylindrical body of the binoculars that houses the optical system and through which the light rays pass.

focusing ring

Ring on each eyepiece for manually correcting for the difference between the user’s eyes.

central focusing wheel

Focusing ring for both the objective lenses; it is used to manually adjust the sharpness of the image.

eyepiece

Optical disk or system of disks through which the eye sees the image produced by the lens.

bridge

Part of the frame joining the two telescopes.

objective lens

Lens that captures the light from the observed object and causes it to converge to form a magnified inverted image.

hinge

Mechanism for adjusting the distance between the eyepieces to the user’s eyes.

Porro prism

Dual-prism system (blocks of glass at right angles) found in most binoculars; it diverts the light rays toward the eyepiece to correct the inverted image formed in the objective lens.

lens system

Optical system made up of a set of lenses through which light passes to transmit a magnified image of an object to the eye.