Big dobsonian telescope1/26/2024 ![]() Building my telescope, watching it swivel so smoothly, seeing the stars, I basked in the reflected glory of that ingenuity. The actual construction took a weekend, and it would be a great project to tackle with kids.ĭobson may be nonchalant about how he used only junk to build his scopes, but it took an impressive mind to figure out how to use that junk in such ingenious ways. You may be able to buy a similarly sized commercial telescope at that price these days, but you wouldn't have nearly as much fun. In essence, it's a telescope built onto a gun mount, which balances through friction as it swivels on an LP record. ![]() That's brilliant." The design isn't intuitive or obvious, but it is wonderfully elegant. As I sawed and drilled, I murmured a fairly steady mantra to myself of "Why on earth do I have to do that? Oh. The collection process turned out to be an enjoyable treasure hunt-but don't worry, the source list we put together below explains how to find everything. Today, Dobson still tours the world to teach telescope building. After 23 years living in a Vedanta (a branch of Hinduism) monastery, where he built telescopes surreptitiously in the basement and then snuck out at night to introduce the neighborhood kids to the stars, he was told he had to choose between life as a monk or as a telescope builder. However, Dobson did choose to promote his sidewalk telescopes at the cost of his longtime home. I based my design on the telescope plans provided by Ray Cash, a member of the San Francisco Sidewalk Astronomers, modifying the plans even further with a few ready-made parts.ĭobson claims he didn't invent the sidewalk telescope, as he had lots of help with his early prototypes. (Optics these days can be purchased in kits online.) Nonetheless, the instructions I used were very similar to Dobson's original Plans for Building A Sidewalk Telescope. I did not admit to him that I didn't grind my own telescope mirrors-something he did with two porthole windows and sand paper-and that I didn't build my own eyepiece out of binoculars. When I brag that the plastics supply store where I finally found Teflon gave me some scrap for free, he exclaims, "Good for you!" We built the mount from window cutouts from schoolhouse doors that had been thrown away." At age 91, Dobson is as passionate about building inexpensive telescopes as he was when he built his first one in 1956. The shingles used to mount the mirror were blown off roofs in storms. This is a far cry from John Dobson's experience when he first built the portable, sidewalk telescopes that now bear his name. ![]() This is in fact true-but collecting the materials takes some doing. I had heard that building a Dobsonian was simple and inexpensive. And no, my local hardware store did not carry Teflon. "Um, I think it might be called Sonotube," I repeated, until someone pointed me toward the concrete form tubes in the garden area. I stood in the store with meticulous notes on the materials I needed, but no one could find them. A massive tube is not usually on my shopping list. I'm a physicist by training, an amateur astronomer by inclination and an occasional visitor to the home center for DIY projects. When I set out to build a portable telescope, known as a Dobsonian telescope, the first step had me stymied-where do you find 6 ft of 8-in.-dia cardboard tubing?
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