You have probably seen old pirate movies where the captains pulls out some kind of a one tube binocular and looks into the distance to find other ships or looks for islands in the distance. That kind of a small telescope is called a monocular and they are used for more than just pirate movies.

Monocular or sometimes called also just telescope, is usually a quite little single tube telescope. It is an altered refracting telescope that is used to increase the created image of a far away object by passing light through a sequence of lenses and prisms. The use of the prisms is the reason why monocular is usually very light when concerning their weight. The overall size and weight are usually more than half smaller and lighter than binoculars, making it very comfortable to carry along and small enough to fit into your pocket or a small purse.

Monocular is sometimes used by visually impaired people to see objects far away that would normally be unreachable for their eyes without any assistance. They can be used to read text on a chalkboard or projection screen. Also in theaters and operas to look what is happening on the stage.