24 inch Altazimuth by Mel Bartels


In 1981, fellow amateur Rob Adams talked me into traveling to Crater Lake National Park with him. It seems that he had read a newspaper story that said that a telescope of 24 inches aperture would be set up. I was sure that this was a misprint. I was quite skeptical while he drove his van for hours. Maybe they meant a 24 inch long telescope. Rounding the final bend after climbing through spectacular mountain vistas brought us to the visitors center. There it was - a giant 24 inch 13 foot long telescope! My astonishment was supreme. We listened to a white haired charismatic gentleman in the evening dynamically present the universe with a slide show and argue for steady state creation. Around midnight the public lines at the 18 inch and 24 inch telescopes dwindled. John Dobson was most gracious in allowing us total strangers to continue observing with the 24 inch. He had but one rule for us: point the telescope away from the rising Sun when we finished. I couldn't believe my eyes: stars where the tiniest pinpoints imaginable and there was no shakiness in the image. We observed until the rising Sun cut us off. All I could talk about on the way home was building a 24 inch scope. Rob Adams threatened numerous times to stop and throw me out of the van if I didn't quit talking! We convinced John to stop in Eugene afterwards to show off his 24 inch telescope. The scope rode on a trailer requiring a license plate. And his son was sleeping inside the 24 inch tube in the RV. His telescopes were very primitive - no drives, no bearings, no fine handcrafting, no complexity and no mirrors. The mirrors are kept in carrying cases and are slipped into the scope base on a piece of cardboard and held in place by gravity and a sling.

Within a very short time, I had a 24 inch blank ordered from United Lens and was corresponding with Bob Kestner (protege of John Dobson, later the lead optician for the COBE optical fix for the Hubble Space Telescope) on grinding large thin mirrors. Years later I joined John Dobson in Seattle Washington to debug John Casino's 36 inch telescope. John has always been most gracious towards me. He attended major star parties and conducted mirror making classes in Oregon for many years. Years later I had an equal epiphany after climbing the 16 foot ladder to the eyepiece of Steve Swayze's 40 inch. Once again, in an aperture I thought impossible, stars were tiny pinpoints with steady seeing. The great lesson here is that we often prejudge telescopes that run counter to the received wisdom of the day.

Here's Dobson's 24 inch at Crater Lake in 1981 and John showing Rob Adams how to lock down the telescope. Next, here I am with my Dobson inspired 24 inch a few years later in a Springfield News article on Halley's Comet. Finally, Swayze's 40 inch with 12 inch finder scope at the 1994 Oregon Star Party..

Draco I

The scope traveled in a trailer, completely assembled. The first iteration proved sensitive to wind. I often observed on the pass, where it was windy, even gusty as a rule. The second iteration made the upper end impervious to wind. I found that using a 6 inch as a finder scope facilitated star hopping, as the field of view in the 24 inch was rather tight. I used the 24 for many years, observing galaxy clusters and other faintest possible objects that I could find in observing manuals and articles.

Draco 2

Coming full circle, here is the 24 inch at Crater Lake joining John Dobson for a public star party in the parking lot overlooking the lake.