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TELESCOPES



So you want to build your own telescope?

 

This page has been put together for all those people relatively new to astronomy who have been calling me recently asking about how to build their own telescope. This has happened, because eight years ago David Young talked me into conducting a telescope building workshop. The intent was to make it possible for a person new to astronomy to build their own telescope for under $100. We knew lots of people got turned off by the not so low priced cheap retail refractors and gave up on astronomy early on. We figured that if we could help these newbies to get a decent first scope they might be more inclined to stick with it.

Since that first class we have helped over 80 people build their own telescopes. The average cost has gone up (due primarily to the cost of the primary mirror) to about $150. But this includes the cost of a good finder, a Daisy BB Gun LED sight, an eyepiece (28mm homemade), and a decent focuser (Helical threaded). The rest of the cost of building the scope has actually gone down due to effective scrounging.

The telescope we make in our workshops is an alt azimuth sidewalk design (also known as a Dobsonian - although John Dobson says he doesn't like that term) and uses a 4.25" F10 spherical mirror from Edmund Scientific. The tube is thinwall PVC 5" diameter pipe reclaimed from the trash at the local telephone company. The other parts of the scope are made from 3/4" plywood. It takes about 1/4 of a sheet now. Thanks primarily to the efforts of Larry Welling, we have managed to effectively reduce the amount of plywood and weight without sacrificing strength. I've posted pictures here of the first telescope I made myself and number 72, the latest scope made by Laura Armstrong, a member of our club, the Astronomical Society of Kansas City.

I really got interested in building telescopes when I started out in astronomy back in 1986. I checked out a book from the local library titled Build Your Own Telescope by Richard Berry, former editor of "Astronomy" magazine. Lots of people have used this book to build telescopes. As a matter of fact there is a really good webpage on the subject at Thoughts on Building a Dobsonian. At the right is a picture of his telescope as shown on his web page. It is very similar to the one I built as a first telescope. It uses 3/4" plywood and a cardboard tube called Sonotube which is used as a concrete form for pouring pillars of concrete. These tubes can be found at most lumber yards. The rest of the telescope is nuts and bolts from the hardware store.

On the left is a picture of my first telescope, a 10" F5 Alt Az "Dobsonian". It is very similar to the one shown in the webpage referenced above. I bought the optics from Parks, because I had recently read a review where their 10" mirror tested the best out of all brands. It is a good mirror and I use this telescope for planetary observing, because it is such a good mirror and shows little distortion at high power.

I also built a squating dog equatorial scope out of Berry's book and have it out on loan to Mac in Leander, Texas at this time. This was the first time I used one of the Edmund 4.25" F10 spherical mirrors in a telescope and was really pleased with the results. That's when I decided to try designing and building a "Dobsonian" using this mirror.

Some of the money saving alternatives we have come up with over the years includes using pieces of gutter strap and threaded rod to make our own secondary holders. We got John Yates, a local club member to sell us some 1" x 1 1/2" first surface mirrors for use as secondaries and we just glue these onto the the piece of bent gutter strap using silicon caulk. It works great. Secondary adjustment is done by just bending the strap until it lines up optically. This seems to work quite adequately and not be too much of an obstruction. We have had few complaints from new telescope owners.

This is an easy telescope to build if you can come up with the right materials. I figure the hardest thing to come up with will be the 5" PVC pipe, but if you go see your local phone company they probably have some of this laying around. It is the shipping container for Carlon Multigard Flexible Bends and is usually thrown away. Why not make scopes out of it? Beats waiting 100,000 years for it to break down in a landfill somewhere. Thanks to Bob Haler at Lymax we now have plans posted for down load at his Cosmic One Web Page. If you are interested in building your own scope you may want to visit there and get the plans. They're FREE!


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