Giant 29" Dobsonian Telescope (Coulter Optical Mirror). Local pickup only. (Can assist with delivery if local)
Primary Mirror aperture: 29"Focal length: 3300 mmFocal ratio: F4.5
This telescope features an extremely rare Coulter Optical 29" mirror. The mirror was originally acquired by the Santa Barbara Astronomical Club in the early 1980s. It made a showing at the 1983 Riverside Telescope Maker's Conference in 1983 (picture attached). I purchased this mirror in 2016, and with a talented craftsman have, over the past two years, engaged in the most daunting building challenge we've ever taken on.
Now, onto the optics! Coulter Optical was founded by one of the greatest opticians of his time - Jim Jacobson. There is good reason to believe Jacobson himself ground this mirror, which itself was beyond the capability of most optical craftsmen at the time. The mirror is 1.5" thick with quite a good figure. Our tests on various objects revealed sharp imagery, particularly on deep space objects like the Dumbell Nebula and Orion Nebula. The Orion Nebula revealed detailed cloud structures I've never observed in any other scope in 25 years of observing. Brightness was stunning. The mirror could use a re-coat in the near future, as it has some mild oxidation, but is completely functional and able to render bright images as is. Mirror sits upon a specially designed 27 point cell that gives it the required stability and flexibility, as well as an adjustable sling that allows for easier collimation. A new dual-speed crayford focuser has been installed on an adjustable apparatus. Balance is superb and actions on the bearing have proven smooth.
The scope is constructed mostly of Baltic birch wood, strong but lightweight, and is lacquered over to provide an protective shine. The telescope has been field-tested and used at recent events like RTMC and NightFall. The scope won a merit award at RTMC for its construction and performance. I have just moved into a new house and have no room for storage! This beast belongs with an enthusiast who can get the most enjoyment out of it possible and can give it a permanent home with plenty of usage.Will throw in the large ladder for free.
Filed under: High-End Telescope Auctions (USA)