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llanitedave
Humble Megalomaniac
Reged: 09/26/05
Posts: 10410
Loc: Amargosa Valley, NV, USA
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Quote:
Since I had never seen a conical mirror finished by anyone else and Bob promotes it on his web site, I maybe erroneously concluded that he had something to do with its development? He certainly has`something to do with its proliferation.
I don't think he developed it, but he certainly seems enthusiastic in promoting the concept. I tend to think this comes from a genuine appreciation of its qualities rather than mere proprietary marketing hype. I'm looking forward to getting mine working!
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"S.O.E." (Sauron's Other Eye) 16" Royce conical mirror: A permanent work in progress.
10" Homebuilt dob, old Coulter mirror
Next Project: The "Eye of Sauron" Observatory!
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Lamb0
professor emeritus
Reged: 07/25/07
Posts: 668
Loc: Fairbury, Nebraska
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I bought premium optics, and critical components such as the focuser, primary cell, secondary holder, and spider. However, the Dobsonian mount is totally home-brewed to fit my requirements. I insisted that the tube assembly be rotatable, and capable of balancing most any combinination of eyepieces and accessories. It's still a work in progress - but it works quite well. There are several used 16" f/4.3 Dobs I'd love to buy as is - however many of the new ones might want a little tweaking. We all find our own compromises. 
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John "Have eyepiece - will travel!"
8" f/5 Dob w/2.14" sec in a 12" alum tube 'The Mortar' - w/PCorr 2° TFoV @ 36.5X ~70% illum *NICE*
Typical eyepieces: 32 Burg, 24 Pan, 20T5, 5-8 SW, Others ALL 2": Pcorr, 2X PwrMt, Ast H-b, Lum UHC + OIII
60mm $50 Walmart Special in training - aka "Backpack Observatory"
Minolta Activa 12x50 , Steiner 15X80
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AstroRealtor
professor emeritus
Reged: 03/26/08
Posts: 538
Loc: Terra Firma
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Quote:
Quote:
Since I had never seen a conical mirror finished by anyone else and Bob promotes it on his web site, I maybe erroneously concluded that he had something to do with its development? He certainly has`something to do with its proliferation.
I don't think he developed it, but he certainly seems enthusiastic in promoting the concept. I tend to think this comes from a genuine appreciation of its qualities rather than mere proprietary marketing hype. I'm looking forward to getting mine working!
I like the idea from a mounting perspective most. Its not as simple as you would like to think to mount a mirror so as to impart no stress to it. To be able to hold the mirror from the purposely designed thickest section of it like you will be doing with a conical mirror seems as stress free as possible. Have you done or seen any fine element analyisis on the idea yet? I'm very interested in hearing how this project turns out.
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mark cowan
Vendor (Obsidian Optics)
Reged: 06/03/05
Posts: 1365
Loc: salem, OR
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There's FEM on this in earlier threads on CN, if you can find it. Not what you'd expect from "as stress free as possible" though, somewhat the reverse in terms of wavefront effect at different altitudes - it was large - but field reports don't detect much of this. The conical blanks have been used in large Cassegrain's for longer then I can remember. 
Best,
Mark
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