OR: OSP 2026 Part II - Telescope Tour
Muriel Dulieu Holzer
The telescope tour started with the 1160mm F/2.8 telescope brokenglas https://quinsightspectre.com/brokenglas/ made by Rob Brown. It is a tensegrity telescope with a superthin meniscus mirror. The word tensegrity comes from tensional integrity. It is a system of tensioned strings and floating compression rods that replace the truss tubes. The silver-coated meniscus mirror was curved on both sides in order to keep its thickness constant and minimize weight. The whole structure, made of plastic and alumicore (a layer of aluminum sandwiched between other materials), was weighing a mere 28 lbs with the mirror. Other interesting features were the brass collimation rods that came half way up the telescope, allowing its owner to collimate while looking through the eyepiece. And he had a set of magnetic filters that could be attached behind the eyepiece with just a tap. I fell in love with the lightness and geometric appearance of this telescope.
Next Rob Brown showed us his spectroscope, which is for sale on his website. It is designed to analyse the spectral fingerprints of stars. The device was coupled with a bright metal tube that acted as a cylindrical mirror to reflect the sun as a line, allowing the device to catch its spectral lines.
He also had what looked like a modified Schmidt-Cassegrain Celestron telescope attached to a box painted black inside with one white side. The sun was reflecting at the bottom of the box and the image was sent back by a mirror through an opening in the box. We could see some sunspots in the image. The quality was not as good as the images I had seen in a Sky-Watcher Heliostar but I could see the sunspots. You can see all of Rob Brown’s creations from the telescope tour in this YouTube video https://youtu.be/BEf0gQTOwaw?si=afoqZVrpW1WXgpIN
Next on the tour was an impressive 28” F\4.5 that was only there to show off an eFinder. I was mesmerized by the size of it and did not listen very carefully.
Following was a 12” F\5 called Romulus. Romulus had 6 truss poles that could be used to collimate the mirrors. The secondary was held by steel wires. And it was resting on an equatorial platform. The design was inspired by Oberon’s build on Cloudy Nights https://www.cloudynights.com/forums/topic/404751-post-your-home-made-scope/page/27/#comment-6425997
The last telescope on the tour was a 17.5” with 4 truss tubes. But what attracted my attention was the homemade eyepiece. The eyepiece was made with a 3D-printed tube and 4 front objective lenses coming from two pairs of destroyed binoculars.
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-Muriel
rayc...@gmail.com
Very creative ATM's, and the fact that you were curious about their designs and shared is just great!
Oh, and regarding "tensegrity," thank you: I learned a new word. I always called this design "stressed-truss design"
Some bridges use this design, as well as Pedersen bicycles.
