Maksutov telescopes are optical telescopes of a catadioptric design that use spherical mirrors and lenses to focus light. The name is derived from a 20th century Russian optician, Dmitri Maksutov, who patented the idea in 1941. The catadioptric optical system which Maksutov telescopes are based upon is also used for a very similar design of telescope known as the Schmidt-Cassegrain model.
Cassegrain telescopes rely on both a primary concave mirror and a secondary convex mirror to focus light. In the Schmidt-Cassegrain design, light enters the telescope and passes through a correcting lens first, after which it strikes a primary mirror, which reflects the light to a secondary mirror that directs it towards the eyepiece through which someone looks. In the Maksutov-Cassegrain design, the primary lens also acts as a mirror by having a meniscus coating of partially reflective material. The light is then bounced off of a secondary mirror that is smaller than the one used in a Schmidt telescope, which gives Maksutov telescopes a slightly better resolution for images in space such as those of the planets.
Since Maksutov telescopes have a slightly diverging corrector lens that gives them higher resolution than the Schmidt design, they have the ability to focus light at a shorter distance, and Maksutov telescope tubes are, therefore, shorter than comparable Schmidt models with the same aperture. The increased resolution means that they also show a darker image of the night sky. The incorporation of the corrector lens and primary mirror as a meniscus coating makes the manufacture of Maksutov telescopes more difficult than Schmidt models, and they are not commonly sold because of their much higher price tag. Popular telescope dealers, however, will usually carry at least one model.
Improvement in the production of Maksutov telescopes has brought their price down as of 2011. Variations on the original design also exist now, such as the Maksutov-Gregory, where the secondary reflection is silvered onto the lens as well, eliminating the need for a second mirror entirely. The Maksutov-Newtonian does not attempt to focus to a minute spot, and instead allows for aberrations and a central area of the image that is obscured from view, to exist.
One other variation on Maksutov telescopes is the Maksutov-Gregorian, which is modeled on the original Gregorian telescope design. It uses a spherical primary mirror and concave secondary mirror with a baffle tube in the center of the telescope body through which the light source is channeled to the eyepiece. The Maksutov-Gregorian is designed almost identically to the Maksutov-Cassegrain telescope, except for the fact that it requires a longer tube to focus the light.