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6" f/8 Criterion EQ | 76mm f/16 Refractor | 8" f/6 Dobsonian |
Astrophotos | Observing | Resources & Links |
The most striking feature of the telescope is easily the yellow tube. Some friends of mine joke that because of the tube, the telescope should be considered an L.E.T (Light Emitting Telescope since it so bright!). So why did I choose that color? I didn't want people to mistake it for a commercially made scope. Prior to painting it I thought about red, white, black, green and blue as other colors, but they didn't seem to fit. Red would have looked like Coulter, white like Orion or Meade, black like Celestron, green (well, how would green look?!) and blue like the very old Coulter Dobsonians.
The construction started by going to a local concrete supplier (Clayton for those of you in Jersey) and purchasing a section of 10" outside diameter Sonotube. They sell tubes in sections of 12' for $17. For that price we were able to cut two 56" long tubes.
Next step was to find a suitable primer with which to coat the outside of the tube. The outside of the Sonotube we purchased had a wax finish, which we opted to leave and just cover. After trying three different brands of sealer/primers, we came across a brand that would do the job well, Kyanize Aquabond (available at any Siperstein's). Once that was established, the tedious task of applying it (we chose to use eight coats in hopes it would bond better and look better than only a couple coats) to the tube began. After every coat the tube became more and more smooth, kind of like a giant egg-shell.
Once the desired finish was achieved, six coats of Safety Yellow latex paint (also by Kyanize) came next on top of the primer. The tube as we know it was then born! However, since completion the tube has begun to chip, flake and distort. Something we should have looked into was removing the wax from the tube prior to priming it since the primer did not adhere to the tube as well as we thought it would have.
A viable alternative to Sonotube is aluminum. Hastings Irragation Pipe Co. sells aluminum tubing, in a variety of diameters and thicknesses, for agricultural purposes, that would certainly do the job for a telescope tube. Right now the price for a tube suitable for an 8" f/6 Dobsonian can be had for approximately $75, a modest price when you think about the cost of the optics the tube will be supporting.