RE: [APML] Another intro

[Jon Kolb <jkolb@mindport.com>]

Jeff,

> I am fortunate to live in a relatively dark area in the mountains 
> outside Denver

Welcome to the APML!  I'm down the street from you in Colorado Springs. I
have to travel to dark sites, and if you're up for this kind of thing,
you're welcome to meet up with me in the field sometime.  Mirror Lake (on
the west side of Tincup Pass) for September's new moon (weekend of 15/16)
looks like my next adventure.  Any bear attacks up your way this year?
There was yet another one with injuries near Westcliffe last night.

> After several months of research (and watching 
> APML), I seem to
> have things narrowed down to an 10" LX-200 on a wedge or a 
> Celestron 9 1/4
> on a G-9 mount that I found used in great condition.  (A good 
> refractor on a
> good mount seems to be beyond my budget at this point.) I 
> know I may be
> opening a can of worms here, but I would appreciate any 
> guidance the list
> may have regarding the respective mounts, etc. for use in 
> astrophotography. 

This is an often-discussed topic here, and should return a lot of hits from
a search of the archives.  In my mind it really boils down to what you want
to photograph first, plus a couple of other considerations like long-term
growth of your system and whether you need portability.  Here's a couple of
thoughts to stimulate your thinking:

1) At well over two meters in focal length, both of the scopes you mention
will somewhat limit your target list.  If you want to shoot the whole of the
North America nebula, for instance, you probably can't reduce these scopes
enough to get it all in.  On the other hand, you could use a reducer to
shoot a lot of other stuff that's not quite so big.  Philip Perkins, in
addition to his excellent astrophotography with the LX200, has a detailed
analysis of this problem on his website: http://www.astrocruise.com/.
Obviously, shooting at f/10 all the time and not using a reducer is an
option, but you'll need very long exposures.

2) If you think you might buy another OTA someday, then perhaps a fork mount
dedicated to a particular scope isn't the best choice for future growth.  A
more generic mount may also make it easier to do piggyback work, since the
necessary counterweights are inherent in the mount, and  don't have to be
added to the OTA itself.  

3) Will you be guiding manually or with an autoguider?  Manual guiding at
2500mm f/l sounds hard to me.  I think it's a challenge at any focal length,
but less demanding in terms of accuracy and frequency of corrections at
shorter lengths.  At f/10 you'll probably need to guide for an hour at a
time, a long time to sit still and concentrate if you're doing it in January
at 9500 feet.

I don't think this is a can of worms, but there are a lot of opinions out
there, and obviously considerations like your budget have to be included as
well.  Best of luck, and let me know if you want hook up in the mountains
sometime.

Sincerely,
Jon Kolb
Adventures in Astrophotography
http://home.datawest.net/jkolb/
jkolb@mindport.com

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