If there is too little friction, the telescope will not stay where it is positioned. If there is too much friction, the telescope is difficult to move to center an object in the filed of view. 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. 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 mounted telescope is popular among amateur astronomers and telescope makers because of its simplicity. WHAT is Dobsonian Telescope and WHY the Tension Control Handle?Ī simple, elegant form of an alt-azimuth mount made to carry a Newtonian reflector was popularized by John Dobson in the late 1970's. It is also substantially more resistant to scratching then plate glass. The great stability of this low expansion glass ensures high quality images. This greatly reduces the cooling time of a telescope larger than 8” in diameter without using an extra fan. Because of its very low coefficient of thermal expansion, Pyrex glass is less affected by changing temperatures. The Sky-Watcher 10” Dobsonian features a primary mirror made of Pyrex glass. Its large aperture size of 10 inches offers you a greater view of fainter celestial objects, greatly improving your viewing experience!
This model also include the new feature-tension control handle. In addition, this model include a 2" focuser with a 1.25" adapter, allowing the use of either eyepiece size. The SkyWatcher 10" Dobsonian Telescope 254mm/1200mm (10") has a "paraboloidal" primary mirror to eliminate spherical aberration and a four-arm, secondary- mirror bracket with fine supports (0.5mm thick), to reduce diffraction spikes and light loss.
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