WHAT is Dobsonian Telescope and WHY the Tension Control Handle?
A simple, elegant form of an alt-azimuth mount made to carry a Newtonian reflector was popularized by John Dobson in the late 1970’s. The Dobsonian mounted telescope is popular among amateur astronomers and telescope makers because of its simplicity. In its simplest form, the Dobsonian mount consists of a box which allows the optical tube assembly to pivot in altitude, while the box itself is swiveled on a base in azimuth. The Dobsonian mount usually relies on the friction between the side bearings on the optical tube of the telescope and a frictional material on the saddle to hold the optical tube in place. If there is too much friction, the telescope is difficult to move to center an object in the filed of view. If there is too little friction, the telescope will not sty where it is positioned. This makes stabilizing the optical tube of the telescope difficult when using a Dobsonian mount, especially when accessories, such as a finderscope or an eyepiece, are added to the optical tub
