Dobson telescopes are telescopes mounted on a swivel similar to that used for a cannon, allowing for easy setup and use. These devices, also known as Dobsonian telescopes, are particularly suited to amateur astronomy because of their ease of use and affordability. Many manufacturers of telescopes and optics produce Dobson telescopes, and it is possible to buy them from scientific suppliers and similar companies. Enterprising astronomers can also build their own.
The basic design includes a tube, a reflecting mirror to gather and focus light, a viewing port, and the mount. The Dobson telescope can offer superb resolution for the size and cost, particularly for objects in deep space, and also has a wide field of view. Operators can easily break down and move Dobson telescopes if they want to be mobile, and the components are simple to make the telescope easy to handle and repair, if necessary.
This design appears to have been developed in the 1960s by John Dobson, an astronomy enthusiast who built on earlier design concepts to develop his telescope. His “sidewalk telescope” proved to be a quick hit with amateur astronomers who wanted to be able to view the night sky but had limited budgets. The ability to make some of the components of Dobson telescopes, like the mount, or even the entire telescope, at home can also be appealing for astronomers on a low budget.
To operate a Dobson telescope, the device can be set up in a good location for viewing, typically at a higher elevation, if possible, to avoid obstructions on the ground and reduce haze. The operator can search for objects through the viewing port, and adjust the focus once an object of interest is visible. Some astronomers work with a pointing device to help them find things that may not be highly visible. It is possible to mount a camera to the telescope to take pictures of various phenomena in the night sky, and for events like lunar eclipses, where the operator may want to get a crisp, clear image for posterity.
Some companies make slightly more sophisticated Dobson telescopes. These include collapsible telescopes that can be broken down to a foldable wire frame. It is also possible to buy a computer control for the telescope and mount. Computer controls allow telescope operators to enter coordinates and adjust the telescope automatically, rather than having to search for a specific point in the sky.