prohibitive and they have been superseded by computer-controlled altazimuth mounts. The simple structure of an altazimuth mount allows significant cost reductions, in spite of the additional cost associated with the more complex tracking and image-orienting mechanisms. An altazimuth mount also reduces the cost in the dome structure covering the telescope since the simplified motion of the telescope means the structure can be more compact. Amateur telescopes Beginner telescopes: Altazimuth mounts are cheap and simple to use. Dobsonian telescopes: John Dobson popularized a simplified altazimuth mount design for Newtonian reflectors because of its ease of construction; Dobson's innovation was to use non-machined parts for the mount that could be found in any hardware store such as plywood, formica, and plastic plumbing parts combined with modern materials like nylon or teflon. "GoTo" telescopes: It has often proved more convenient to build a mechanically simpler altazimuth mount and use a motion controller to manipulate both axes simultaneously to track an object, when compared with a more mechanically complex equatorial mount that requires minimally complex control of a single motor. Gallery See also Dobsonian mount Equatorial mount Heliostat Horizontal coordinate system – a system to locate objects on the celestial sphere via Alt-azimuth coordinates Parallactic angle Solar tracker Tripod References External links Images of the Unitron altazimuth mount Telescopes ja:天体望遠鏡#経緯台式架台