NCA Telescope Making and
Mirror Grinding Classes

6:30 - 9:30pm every Friday night except for Federal holidays and major snowstorms

Chevy Chase Community Center

5601 Connecticut Avenue, NW
Washington, DC
If the answer to any of those questions is 'Yes', and you live in the Washington, DC metropolitan area, then you need to come to the NCA telescope-making workshop that is held just about every Friday night at the Chevy Chase Community Center.

Sure, you can purchase a ready-made commercial telescope for a few hundred dollars or more, but you won't really know how good that commercial mirror is until you test it, which most people don't know how to do. We do, and we can show you how to test it with a simple tester you could build yourself in an afternoon.

One of the great things about making the optics yourself is that with your own hands, and with no power tools, you can make the most amazingly accurate large surface that is humanly possible - a medium-sized parabolic mirror, accurate to a very small fraction of a wavelength of green light (that is, only a handful of layers of molecules) of perfection over the entire surface. And the views are sharper and brighter than those of any catadioptric telescope of the same size (i.e., Schmidt-Cassegrain or Maksutov designs). And it's much cheaper, to boot.

In any case, the NCA (National Capital Astronomers) has sponsored this telescope making workshop since the late 1930's. The class been held in quite a few different locations around the DC metropolitan area, including at the American University's Physics Department. Jerry Schnall, who is retired from the U.S. Patent Office, took over the workshop about 1968. He has helped thousands of people since then to make telescopes of various sizes. Because of poor health, he asked to be relieved of the duty of running the workshop about 2 years ago. Guy Brandenburg, a math teacher in the DC Public School system, who had previously made two mirrors under Jerry's extremely competent and knowledgeable direction, volunteered to take over (with a lot of trepidation), and has been running the workshop, usually with Jerry's expert advice, ever since. Part of that job included organizing large numbers of very strong people so that we could move the lathe, the aluminizer, all the glass, all the grit, and all of the other odds and ends from the American University campus to the current location at the CCCC.

On any given Friday, there are likely to be from three to eight people of all ages working on various projects, at various stages of completion. 'Classes' are very informal, and you can start and finish a mirror or telescope at any time.

We only charge for materials!

The price covers:

It does NOT include coating the mirror; the secondary mirror; the mirror mount; the secondary holder; the focuser; or eyepieces.

You should be able to get your mirror to within 1/4 wavefront error without too much difficulty, but most of our recent  mirror-makers are successful at making them much better than that.

We also have an vacuum-chamber aluminizer to put the final, super-thin layer of reflective metal on your mirror. Aluminization costs a little extra - approximately $20 for an 8" mirror. But you have to help.

Some people buy their own kits from places like United Lens, Newport Glass, Willmann-Bell, or Dan Cassaro. You will  find that it's cheaper from us, however, because we re-use the tool, and because those places have to sell you much more grit than you need.

We even have some basic woodworking machinery so that you can make a good part of the rest of your telescope in the same location, which was originally a woodworking shop. We even have a metal-working lathe, if you know what you are doing with one. However, making the mount involves a lot of sawing, sanding, glueing, nailing, drilling,screwing, and painting, which means that you end  up doing a little bit of work, letting it dry, then putting on another coat the next day or a few hours later. It would be rather inefficient to leave all of those steps to Friday evenings. Thus, most people make the optics at our workshop and make the rest of the telescope at home (garage, living room, basement, etc).

Quite a few people have come in to have us evaluate mirrors that they have purchased or that they have made themselves. Others have started a mirror on their own, but need a little advice on finishing things. Others want help on collimating (aligning) their commercial scopes. All of those requests are welcome, and are done for free, as a public service.

Contact Guy Brandenburg at or 202-262-4274.

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last updated on July 27, 2003