ATM Re: "What do you recommend"?

[andydtg@alpha1.phoenix.net]

Tom Cathey wrote:

>Let's say that you want to image faint galaxies with the highest resolution
>possible, you have a country location 30 miles from a major city (stars are one
>magnitude dimmer than Stellafane if you've been there) , for fixed stationary
>use, and forget about money for now...

Actually the stars are the same brightness (unless the air pollution is
*really* bad) - the higher background at the light polluted site just makes
them harder to see.

>What is the "human engineering" or technical advantages of using a Schmidt
>Cass over a big Newt?? Why does it seem many amateurs are going to them for
>CCD work? Is it the small portable size, or the ability to change F ratios,
>or precision out of the box tracking? 

You've answered your own question, also, as others have pointed out, the
great majority of new CCD observers are using scopes they already have.
I think we're just at the beginning of a new phase in amateur astronomy
where telescopes, visual observing, CCD imaging, and computer aids will
become more integrated. The commercial SCT's are currently in the lead
in this area because of the large potential market. Large amateur systems
will still be self-built because of the small potential market.

>Is large aperature, which is relatively cheap in Newtonians, not as important
>for high resolution as these trade offs?

High resolution of 'what' is important. Given the fixed size of the CCD chip
an image of a large bright object with a small scope contains the same amount
of information as an image of a small faint object taken with a large scope.
The difference is that there are a *lot* more small faint objects than there are
big bright ones, so a big scope lets you image more of the universe than a
small one.

>I wonder if from average experiences in the real world most
>amateurs have found that given their "average" non-observatory locations that
>seeing is such a big problem that large aperature is useless most of the time
>(seeing) for long exposure (or any) CCD work....and settle back to just a 10"
>or 12" LX-200 for its high accuracy and easy interface features.

This is kind of hypothetical, as I doubt there are very many folks out there
who gave up their 24" + scopes to do CCD with 10-12" scopes.

>I guess what I mean is that if you had a 40" F4.5 that could track as well
>and point as well as these commercial wonders, is it a waste of time and
>money for PURE results because on average seeing, etc??...or other reasons??

See Al Kelly's web page (http://www.ghgcorp.com/akelly) to see what can be
done with a large (32" f-4) amateur scope and a home built Cookbook CCD
camera. He has actually imaged gravity arcs previously seen only by the
HST and 6+ meter ground telescopes!

>I mean look at the fire sale deals on Newts these days in the ads as opposed
>to how the "rice boxes" are in demand and holding their value...whats this
>telling us?? That's why I wonder about the wisdom of my thinking of building
>up a dedicated 40" CCD Newtonian.

Building a large scope & expecting to recoup your money is probably not a good
bet, just because it's built to *your* specs and may not be what anyone else
wants. If I'm going to spend a lot of $ time and effort on a *big* scope it'll
most likely be designed for my purposes and no-one elses! 



Andy Saulietis / DTG Alt-Az-Fp Drive Systems
12617 Harriet Ln
Santa Fe, TX 77510 USA
409-925-8854 Voice/Fax