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Re: [ATM] Need Advice on Mounting & Driving a 16 Inch Newtonian
Richard wrote:
> Hi Eric,
>
> Thursday, July 12, 2007, 11:39:49 AM, you wrote:
>
> ESJ> equatorial. And not just any equatorial, I would go with the ball base design
> ESJ> also known as trackball.
>
> Why do you call that.. that... "thing" equatorial?. It's no more
> equatorial than a dob, surely?. I would have thought the only thing
> going for it, other than novelty factor, is portability, the one thing
> that is not important to David.
>
it's all in how you drive it. If you set up the bearing mounts the right way,
its equatorial. If you set it up the other way, its altitude/azimuth. there is
an article referenced from that page showing how a ball based mount can be go-to
ized. So, the reasons why I think this is a good idea: 1) it's simple. Far
simpler than traditional mounts. 2) the drive mechanisms are much simpler and
smoothness of driving is a function of smoothness and stiffness of your ball
surface. 3) you can use a flat platform on the ground to hold the telescope and
not worry about digging down God knows how many feet and how wide to put in a
pier that will be stable. I've done that (and arms suffered greatly) so
anything that can be mounted on a flat spot is a good thing. 4) related to 3 is
that the eyepiece height is minimized.
The biggest negative feature about this design is that you create a really long
lever for the wind to catch. Don't know of any solution to that but on the
other hand, some of the dobs with a low base have the same problem in the wind.
Anyway, that's my opinion based on having been part of building mounts for a few
telescopes in the past and never being quite happy with the results.
Seems to me it would be rather simple to build a prototype and try it out. Use
the single stalk design people have talked about here for a quick test.
Although it might be a bit difficult explaining the mass to the trash man if you
decide to throw it out. :-)
---eric
--
Speech-recognition in use. It makes mistakes, I correct some.
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