AMATEUR TELESCOPE MAKING
I made my first mirror and telescope in my teens, and then did other things for close to fifty years. Now I'm pushing glass again. This is just a convenient place for me to keep track of the process. For a wealth of information about amateur optics and telescope making, visit the Stellafane web site.

 

Click for downloadable STELLAFANE CONVENTION BROCHURE

Monday
Jan172011

what i’ve been doing instead of blogging

I grew up in Springfield, Vermont. When I was a kid, Springfield was home to around 10% of America’s heavy machine tool industry. Several thousand engineers, machinists, draftsmen, patternmakers, and other skilled workers were employed by  “the shops,” and the USSR purportedly had Springfield on its list of nuclear missile targets because the lathes and grinders that came from the Jones & Lamson Machine Company, the Fellows Gear Shaper Company,  the Bryant Chucking Grinder Company and others were critical to American manufacturing of everything from toasters to cars to our own missiles and bombers. Now this is all gone. I guess we build our stealth fighters now with machine tools made in Korea or Taiwan. Springfield’s primary current claim to glory is a rapidly fading memory of having won a contest to host the premier of the Simpsons movie.

One incidental offshoot from the old shops remains, however, stronger than ever. In 1920 a brilliant polymathic engineer (and architect, and polar explorer, and artist…) named Russell Porter, who was employed at Jones & Lamson, brought a group of machinists and other Springfield workers together and taught them how to make telescope optics. At the time, buying a decent astronomical telescope would have been far beyond the means of a factory worker with a yen for amateur astronomy—so amateur astronomy barely existed. Porter’s little group formed a club, the Springfield Telescope Makers, and built an observatory on some land Porter owned on a hilltop near Springfield.

Stellafane, as the place is called, is a contraction of Stellar Fane, “Shrine to the Stars.” It is the birthplace of a burgeoning worldwide hobby—the making and using of telescopes for astronomy—and astronomy is one of the few scientific disciplines where amateurs can still make real contributions. The list of supernovae, comets, and obscure astronomical objects discovered by amateurs using backyard telescopes grows longer seemingly by the month, and amateurs do important work measuring the changing output of variable stars. for a few days at the end of July or the beginning of August every year, thousands of amateur astronomers and telescope makers converge on little Springfield, Vermont for the largest convocation of telescope makers and users on the planet, the Stellafane Convention.

When I was a kid I answered an ad much like the one that Porter posted on a bulletin board at J&L, and enrolled in a Stellafane-sponsored class in telescope mirror making. I ended up building a 6" F9 Newtonian telescope, showing it at the 1963 convention, and becoming a member of the club. Stellafane was pretty much the center of my high-school life, geek that I was. 

But time passed, and I went off to college, changed my focus from science to art, and drifted away from Stellafane and the Springfield Telescope Makers.

Until a little over a year ago. Then  I rediscovered, through a circuitous chain of circumstance, that the Springfield Telescope Makers still offer telescope mirror-making classes. On impulse I signed up. I should note that the classes are very popular, and fill up quickly, and that my story of long-ago involvement had a lot to do with my even getting into the class.

But I'm hooked. I ground, polished, and “figured” an 8-inch f5.6 mirror and am working on the ‘scope to house it. I'm also currently working on a 6-inch f4.2 mirror. Though smaller, this is more challenging because of the fast focal ratio, but will (with a rather expensive corrective lens to deal with “coma”—we can talk about that later), yield a wide-angle image good for chasing comets or looking at large astonomical objects like nebulae.

One reason for reviving this blog is to post my thoughts on the process of making these optical surfaces. It completely fascinates me that it is even possible, using just one’s hands, to make surfaces accurate in shape to millionths of an inch, a small fraction of a wavelength of light.

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