When you have more than a passing interest in amateur astronomy, you quickly find that the hobby can get expensive fast, especially when you start dreaming about getting a bigger scope that will collect more light.
Maximizing the aperture to cost ratio is the Dobsonian telescope, a simple large-aperture reflector on an alt-azimuth mount, named after John Dobson, a former Hindu monk turned amateur astronomy evangelist. The Dobsonian and its numerous variations are designed to be easily built using inexpensive materials, and it has become one of the favorite tools of the sidewalk astronomer.
John Baichtal at Wired’s geekdad blog posted a few resources for building your own Dobsonian today. Of these, Craig Jones’ documentation of his own telescope design (pictured above) provides a really nice walkthrough of the telescope making process.
The critical element of any reflector telescope design is its mirrors. It still amazes me, but it’s possible for a non-specialist to grind their own mirrors as well. While it takes a significant amount of time and patience, it doesn’t take expensive tools or years of experience. In his mirror grinding howto, David Bourgeois writes:
At some point it becomes a fascination for many people to get a better instrument. Unless you have a large pocket book, the only practical way to make a large instrument is on your own. Depending on your resourcefulness and ingenuity, you may save yourself considerable money. The down-side of this is, however, a good bit of time and work. But if the idea of making something accurate to a few millionths of an inch with nothing more than two bits of glass, some common tools, and some jury-rigged testing apparatus appeals to you, then a bit of work won’t stand in your way!
Because of the Dobsonian’s popularity, there’s really a wealth of information and resources available online for building one from the ground up. You’ll still be putting money into the right eyepieces, but with a bit of research and time you can gaze at the heavens with a much larger scope than you can afford to buy. All with the satisfaction of having built a precision instrument in your own workshop.
References:
Build Your own Dobsonian Telescope – Link
Craig Jones’ Dobsonian Documentation – Link
Grinding and Testing a Telescope Mirror – Link
Dobsonian Telescope @ wikipedia – Link
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