The Amateur Telescope Maker’s Page (Oct, 1949)
If you want to get an idea of how much amateur astrophotography and related technologies have come in the last 60 years, check out the image on the top left which was made at the Palomar Observatory. Now look at some of the stunning photos amateurs have taken recently. For comparison, here is one from Hubble and another that is a composite of images from Hubble, Spitzer and GALEX.
The Amateur Telescope Maker’s Page
Conducted by Robert Brightman
The giant spiral nebula known as Messier 81. Its distance is three million light-years. The central part consists of stars so close together, it is impossible to resolve them. A time exposure made through Mt. Palomar telescope.
THE sketch at the bottom of this page indicates the method used by Sylvestus B. Burdakin of Elmwood, Connecticut, to achieve an adjustable bearing surface for his alt-azimuth mounting. True, it is a variation of a theme but we think our readers will find it interesting. His letter follows: “Having finished my telescope, I decided to let you know of a couple of ideas that have proved helpful. Although my mirror did not come out perfect I can use it with good results on the moon. Later I intend to make another mirror, and get it perfect, I hope.
One idea I tried on the full moon was to put a piece of cardboard over the tube, with a hole about the size of a quarter or half-dollar in it. By so doing, I find that I can get a very good view of the craters and mountains. Otherwise the light is too strong and I can see nothing.
My other idea, for making a terrestial telescope without too much trouble, was to use a roof prism. I bought one for a dollar, from the Edmund Salvage Co. It works equally well in observing the moon. Changing prisms is not too much trouble. It makes a two-in-one telescope at a slight extra cost.
To date, I have spent about $32.00 in building my ‘scope but that includes a tripod. I also mounted it a little differently than yours. Enclosed is a diagram of the mounting I made.”
This letter, by Herbert S. Roberts, describes the telescope illustrated at the top of this page: “It took me 60 hours to grind and polish the mirror. I ground it by keeping one eye on the glass and the other on MI. I shipped it to John Pierce for testing and on the third try it passed.
The tube is made of a war surplus powder case. It is 5 ft. long by 6 in. in diameter and it cost me just $1.60.
This is really a fine instrument. With a quarter-inch eyepiece, it will split the rings of Saturn very clearly. Focused on the moon, the results are just short of amazing.
Carl Davis of Milford Center, Ohio, has come up with a practical means of eliminating the rainbow effect apparent when making a refracting telescope with simple, long-focus lenses. He uses a cardboard diaphragm to mask out all but the center of the lens. The improvement he states is quite “startling.” See drawing below.