From: "Mel Bartels" 
To: 
Reply-To: "Mel Bartels" 


>>>
The information I seem to be finding on the Web, today, leads me to believe
that more ATMers are leaning toward a lightweight Dobsonian mount on an
equatorial platform, similar to the old Poncet table. Is this true and why?
<<<

Boy, I don't know if anyone can really say.  Star parties will give one
impression, but what people use at home may be something else.  I'd
concentrate more on what fits me and less on where the crowd is stampeding.
Today the choices are greater than ever.

>>>
 Here in Charlotte, NC light pollution is so bad that
deep sky observing is difficult, so I am wanting to build a scope mainly
for planetary or lunar observing and photography, so I will need drives for
both axes.
<<<

Then you ought to consider a longer focal length 8 to 12 inch scope.  The
larger aperture has an advantage with digital photography because the
shorter exposures are less bothered by atmospheric turbulence.  One
question you should answer before diving in is, "What budget?" 
And, what observing situation exactly?  Can you build a small observatory
shed, or do you need to wheel or carry the scope around?

>>>
 I had been considering building a fork mount using fiberglass over
foam core products (or whatever is available today)with a truss OTA, but
maybe I should consider a lightweight truss Dobsonian on an equatorial
platform. What would be the pros and cons?
<<<

I'd get the design first, then worry about the implementation.  A fork
mount is not the best choice for a long focal length instrument because the
fork arms will be rather long in comparison.

>>>
If I choose the latter, the
question is immediately raised about converting Alt-Az coordinates to
RA-Dec coordinates; how is this easily accomplished? This leads to the next
obvious question of how to integrate a laptop pc or PDA to a non-commercial
scope.
<<<

If you want off the shelf components, you can find digital setting circles
fairly inexpensively that will suit your planetary/lunar observing needs
nicely.  You don't need goto for that.

Mel Bartels

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