Reasons to purchase a Dobson telescope
Many hobby astronomers prefer a Dobson telescope. This telescope will often be a Newton telescope and it is mounted with widely available materials. Most Dobsonian telescopes are big but they still fit in your trunk.
The differences between a Dobson telescope and a reflecting telescope
A Dobson telescope differs from an ordinary Newton telescope (or a reflecting telescope or reflector) on the following aspects:
- The Dobson has a thin mirror
- Its mirror diameter is bigger
- It has a shorter focal length
- The telescope often has a floating mirror
- It has a different tube
- It has a simple alt-azimuth mount
Its mirror obviously weighs less than thicker mirrors so it is able to handle a much bigger diameter. The Dobson telescope has an alt-azimuth mount so single-arm secondary mirror support will suffice.
Disadvantages of a Dobson telescope?
Does the Dobson telescope have any disadvantages? As the Dobson telescope is not motor-driven and the celestial bodies cannot easily be found, this telescope is not suitable for astrophotography. As a result, you will have to keep tracking the stars yourself. Because of the rotation of the earth you will have to readjust your telescope already after several minutes. In addition, the telescope may start experiencing balance problems when you hang accessories on it. You can easily solve this problem, however, by hanging a counterweight on the telescope. Yet most Dobsons can deal with a small degree of imbalance. For a telescope with alt-azimuth mount it is difficult to find objects that are right above you (zenith). Improvements in the material carrying the alt-azimuth mount and the design may diminish these problems but they cannot completely eliminate them.
For the amateur astronomer
Despite these disadvantages a Dobson telescope is a very good choice when you are a hobby astronomer and prefer a relatively cheap telescope that is easy to transport and set up.