In the field of amateur telescope making most, if not all, of its design features had been used before. Dobson himself identified the characteristic features of the design as lightweight objective mirrors made of porthole glass , and mountings constructed from plywood , Teflon strips and other low-cost materials. Dobson optimized the design for observation of faint objects such as star clusters , nebulae , and galaxies what Amateur Astronomers call deep sky object s. These dim objects require a large objective mirror able to gather a large amount of light.

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Gear-obsessed editors choose every product we review. We may earn money if you buy from a link. How we test gear. By Karen C. Fox Oct 9, 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.

A massive tube is not usually on my shopping list. I stood in the store with meticulous notes on the materials I needed, but no one could find them. And no, my local hardware store did not carry Teflon. I had heard that building a Dobsonian was simple and inexpensive. This is in fact true—but collecting the materials takes some doing.

The cardboard tubes were lying around. The shingles used to mount the mirror were blown off roofs in storms. We built the mount from window cutouts from schoolhouse doors that had been thrown away.

When I brag that the plastics supply store where I finally found Teflon gave me some scrap for free, he exclaims, "Good for you! Optics these days can be purchased in kits online.

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.

However, Dobson did choose to promote his sidewalk telescopes at the cost of his longtime home. 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.

That was in Today, Dobson still tours the world to teach telescope building. As I sawed and drilled, I murmured a fairly steady mantra to myself of "Why on earth do I have to do that?

The actual construction took a weekend, and it would be a great project to tackle with kids. Dobson 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. Building my telescope, watching it swivel so smoothly, seeing the stars, I basked in the reflected glory of that ingenuity.

I am hooked.



Gear-obsessed editors choose every product we review. We may earn money if you buy from a link. How we test gear. By Karen C.


Homemade 12.5 Inch Dobsonian Telescope

Their step by step instructions were invaluable to me as I built this scope. The focal length of the mirror is 61 inches. Technically, it should have been I installed the spider first, about one inch down from the end of the square end of the tube. I then temporarily installed the secondary mirror so that I could measure the approximate distance to the center of the secondary in order to locate the holes for the focuser. I centered the focuser 8 inches from the top of the tube, using a 2.


How To Build a Dobsonian Telescope: DIY Astronomy Project

This is not a critical dimension, so I rounded up at 11 inches even. Stellarfane recommends a margin no less than 2 inches and no more than 8 inches. The height needs to be approximately 1" less than the maximum height of the Rocker Box after arc for the Altitude Bearing has been cut out. For my it was 16". Bottom: I used the router and arm described previously only the base piece was 18" so the pivot point was 9".


Dobsonian telescope

Dobsonian telescopes are popular with amateur telescope makers for their ease of design and construction, portability, and their use of large optical mirrors. Pioneered by John Dobson in the s, the instrument combines a Newtonian reflector telescope with a unique two-axis movable base. It uses a primary mirror to capture and reflect light, a secondary mirror to direct light into an eyepiece, and a focuser to make fine adjustments for viewing. My finished inch Dobson telescope.

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