Types of Telescopes

Other Telescope Designs

Refractors, Newtonians, and Schmidt-Cassegrains are the most popular telescopes for amateur astronomers.  Maksutov-Cassegrains andRitchey-Chrétiens are also reasonably common, with catadioptric Newtonians (Schmidt-Newtonians and Maksutov-Newtonians) growing in popularity for certain applications.  For most general-purpose observers, these types of telescopes offer everything that is needed.  But there is no shortage of unique and unusual telescope designs for… More »


Above:  Optical layout of a typical Ritchey-Chrétien, with CCD camera attached Ritchey-Chrétiens have become popular in recent years for deep-sky imaging.  They are intended primarily as photographic instruments and are not as well-suited to visual observing, but for imaging smaller deep-sky objects such as galaxies and small nebulae, they are hard to beat.  Ritchey-Chrétien is… More »


Above:  Optical layout of a typical Schmidt-Newtonian Schmidt-Newtonian telescopes are a modified version of a standard Newtonian.  They incorporate a Schmidt corrector lens like that found on aSchmidt-Cassegrain telescope.  This lens minimizes some of the aberrations associated with a standard Newtonian.  Schmidt-Newtonians are usually well-suited to both visual observing and photography.  The name of these… More »


Above:  Optical layout of a typical Maksutov-Cassegrain Maksutov-Cassegrain telescopes are an alternative design to the similar Schmidt-Cassegrain telescope (SCT).  While similar in most respects, there are a couple differences that have prevented Maksutov-Cassegrains from becoming quite as popular as SCTs.  Probably not the least of which is the fact that SCTs have a nice abbreviation… More »


Above:  Optical layout of a typical Schmidt-Cassegrain Schmidt-Cassegrains telescopes (SCTs) have become one of the most popular types of telescopes.  This is due to the versatility and compactness of the optical design.  SCTs are only about twice as long as their aperture, making them highly portable.  They are also well-suited to a number of applications… More »


Above:  Typical Dobsonian telescope A Dobsonian telescope is optically identical to a Newtonian telescope; the difference is in how the telescope is mounted.  A Dobsonian has a lazy-Susan type base that swivels left and right, and the telescope rides on two hubs that allow motion up and down.  What makes a true Dobsonian is that there are no… More »


Above:  Optical layout of a typical Newtonian For sixty years after the invention of the astronomical telescope, all telescopes were refractors.  However, refractors suffer from chromatic aberration because the different colors of light do not focus to the same point.  Isaac Newton studied this problem (in his free time between inventing calculus, developing modern physics, and being beaned on… More »


Above:  Optical layout of a typical refractor When most people think “telescope” they think of a refractor.  The very first telescopes, including Galileo’s, were refractors.  In fact, all telescopes were refractors until Isaac Newton invented the first reflecting telescope in 1669, six decades after Galileo first pointed his telescope to the heavens. How Refractors Work The… More »