Monoculars & Golf Scopes A monocular is a modified refracting optical device used to magnify the images of distant objects by passing light through a series of lenses and prisms; the use of prisms results in a lightweight construction. Volume and weight are less than half those of binoculars, making it easy to carry. Monoculars are often used by visually impaired people to see distant objects that would normally be indiscernible. For example, they are often used to read text on a chalkboard or projection screen. Besides their use by the visually impaired, they are also used in hunting, survival and espionage. For these specific tasks smaller monoculars are made that fit inside a regular pocket and they are frequently referred to as "spy scopes".