What is a Dobsonian mount?
A dobsonian mount is a simple altazimuth mount that is usually made of wood, has bearings of Teflon® running on Formica® (or similar substances), and is held together by gravity. It is usually used for mounting Newtonian reflectors, and offers the most cost-effective way to own a telescope of reasonable aperture. It is named after the legendary John Dobson of the San Francisco Sidewalk Astronomers http://www.sidewalkastronomers.com /, who popularised it.
The Dobsonian mount was first introduced by John Dobson and has gained wide popularity among amateurs because it is highly portable, easy to build and relatively inexpensive. The key points in the mount are the two bearings, the altitude (vertical) and the altazimuth (horizontal) bearings both of which consist of a Teflon pad with a metal, vinyl or Formica surface resting and rotating on it. The only major disadvantage is that it is not equatorial so you cant track objects or use setting circles for aiming (you can get digital interfaces which will calculate the location of objects on a alt-az mount for a few hundred dollars) or some people build a motorized equatorial platform that will track by tilting the base of the mount.
