The Father of Aperture Fever

Some background on John Dobson's contributions to telescope making. By Jack Eastman.

John Dobson came along well after I'd finished my serious telescopes, more or less in the spirit of Warner and Swasey-- near infinite mass. My 32-cm (12.5") Dobsonian telescope weighs somewhere in the vicinity of 1100 pounds, but is reasonably stable, and weather proof.

Could we refer to John as the Father of Aperture Fever? His contributions regarding very large telescopes (of 1950's standards) have helped innumerable folks obtain large instruments, even small ones, at minimal cost, thereby bringing the hobby to many, many more folks who otherwise might not have been introduced to astronomy. Of course this goes hand in hand with John's other outstanding contribution, outreach, again bringing astronomy to many folks through his co-founding of the San Francisco Sidewalk Astronomers, and the subsequent formation of similar groups around the country.

It's interesting to note that the pros seemed to also get in the spirit of John's telescope building philosophy. Thinking that an Infrared telescope wouldn't need to hold the tight tolerances of one for visible light, some 'scopes were built with thinner optics and much lighter mounts. These worked well, even in visible, and the use of Alt-Azimuth mounts allowed much bigger 'scopes. Recall, from the talk "Journey to Palomar" nothing about the 5m (200") was possible when it was in the concept phase. Now 8.5m (340") seems to be quite common. I think the Grand Old Lady of Palomar is something like 15th or 20th in size today. Of course, with segmented, or multiple, mirror technology, it seems there is no upper limit to the size of a telescope. (8.5m seems to be the limit imposed on the need to transport the things! I like to think Roger Angel and his crew would tackle a 10m if there was a way to deal with it after the casting) I like to think John Dobson was instrumental in this telescope building philosophy.

As for my own trip through the minefield of telescope making, more in the spirit of Russell W. Porter and all, I offer the following. Here's the story of the build of a couple of 'scopes:

and the refractor: