What is "optical telescope"

n. an astronomical telescope designed to collect and record light from cosmic sources

An optical telescope is a telescope that gathers and focuses light, mainly from the visible part of the electromagnetic spectrum, to create a magnified image for direct view, or to make a photograph, or to collect data through electronic image sensors.

There are three primary types of optical telescope:

• refractors, which use lenses ( dioptrics)
• reflectors, which use mirrors ( catoptrics)
• catadioptric telescopes, which combine lenses and mirrors

A telescope's light gathering power and ability to resolve small detail is directly related to the diameter (or aperture) of its objective (the primary lens or mirror that collects and focuses the light). The larger the objective, the more light the telescope collects and the finer detail it resolves.

People use telescopes and binoculars for activities such as observational astronomy, ornithology, pilotage and reconnaissance, and watching sports or performance arts.