Re: [ATM] 40" mirror

["Jerry B. Hillman" <JBHillman@ev1.net>]

Hi Jeff,

This mirror will be a truss tube Dobsonian.  I wouldn't even attempt
something else.  The mirror will be made of pyrex, 40" in diameter and 4
inches thick. solid, not slumped, not anything exotic. I know it will weigh
about 400 pounds, but once any mirror is to heavy for me to lift, dealing
with the weight becomes an engineering problem, not a physical strength one.
It will be used exclusively for visual observation.  I have smaller
telescopes that would be easier to do astrophotography with.

I have been to Steve Swayzies (sp) website and looked at his F5 - 40" x 2"
thick mirror and the resulting 17 foot telescope. I have looked at the
Obsession telescope site.  These are large, massive telescopes. Very
impressive, and the manufactures claim they are easy to use.  I just want to
collect enough information before I start grinding, or cast the mirror with
the curve pregenerated, so that I can make an informed decision.

Clear skies, Jerry

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