Re: [ATM] ground ring diameter vs. mirror diameter

[Dale Eason <atmpob@yahoo.com>]

Twice sounds way too much to me.  Check out Greg
Babcocks 24 inch scope with a 32 inch ring.  That is a
1.3 ratio.  

http://synrgistic.com/astro/24inch.htm

Most of what I have seen of that design as well as my
own scope have about that ratio.

Dale Eason


--- Dave Smith <smithersscope@yahoo.com> wrote:

> 
> Thanks to everyone that responded to my question.
> I've
> begun the rebuild. For those that might be
> interested
> or find interest in this thread somewhere down the
> road I'll add one other observation. On my first
> iteration of the 16 inch tri-dob, I tried "too" hard
> to keep the footprint small. So much so that I
> didn't
> leave myself enough room inside the mirror box to
> work
> with. So, John's comments are correct. Design the
> mirror box first with all your requirements
> included,
> then build the ground ring and flex rocker to match.
> It just sounds ironic that you need a footprint
> roughly twice as large as the mirror diameter! 
> Thanks,
> Dave
> --- John Sherman <atmer@johnspics.com> wrote:
> 
> > 
> > 
> > Hi Dave,
> > 
> > > ring and flex rocker...can you comment on the
> > ratio
> > > of ground ring to mirror size?
> > 
> > That sounds about right. I have a 40" ring under
> my
> > 22" mirror. After you 
> > build your mirror box, you build the rocker to
> fit.
> > Then measure the 
> > diagonal across the bottom of the rocker, and that
> > is the diameter of the 
> > ground ring. While it may sound huge, it doesn't
> > really add to the dimension 
> > of the scope as a whole, since the rocker will
> > already use that amount of 
> > space as the scope is moved in AZ.
> > 
> > Good luck with your project!
> > 
> > John
> > 
> > 
> > 
> > 
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> > 
> 
> 
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