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[APML] Guidescope / set-up question / Thanks!!!
Hi APML,
thanks for all your responses, sorry for my two day delay in response!
Comming from a mass prodution telescope (M....) with "drive in" capeabilities,
it's very hard for me to figure out on what to get and to do, when combining a
individual astrophotographical setup for the future.......
Now to your answers (thanks again!), here we go....
Bert:
>The ETX definitely has mirror shift, which
>a refractor guidescope does not have. The focus shift with an ETX is much
>worse than with either refractor that I use. Yes the refractor OTA is much
>longer than the ETX but with good mounting, that should not be a problem. I
>use the A-P 80 mm f11 guidescope with my 130 f6 refractor and a 160 f3.3
>Newtonian (Tak Epsilon) and it works very well with both
Dear Bert,
I have had some complaints with a ETX as guidescope in my mind (some month ago
posted on one of the lists) - this was what I've thought, thanks!!, this made my
mind clear!
>There is certainly no sense in trying to
>optically align the guidescope with the celestial pole or anything else. The
>mount is what has to be aligned, and you should do that with the imaging
>scope, NOT the guidescope.
I think I didn't explain this correctly - I meant the alignement between the
photographic and the guiding scope - I thought they have to be perfect aligned
to each other (besides the polar alignement of the mount).
Is this not needed ??? - could the guidescope be 1 - 2 degrees of the
photographic instrument (when alignement of the photographic scope is perfect),
I thought that I would receive "trails" on my image?!?
>I would suggest getting a pair of good heavy
>rings of the Losmandy type (I use 125 mm rings) and Losmandy plates, make
>sure every thing is snugged down good and tight, and stay with the refractor
>guidescope.
Losmandy rings sound like the most recommended solution from all of the
replies, even though they are very pricey, so many people can't be wrong! Do you
know how they can be combined with the Vixen rings, I have in my R200SS?
Ray:
>Probably referring to a typical piggy-back type guidescope mounting in which
>the guidescope in this situation would extend significantly past the Newt
>and would possible be in the field of view if it is 25" longer. But your
>side-by-side Losmandy mounting would work extremely well if you can balance
>it and eliminate the flexure adequately.
Dear Ray,
side-by-side is an option I was also thinking about, are these plates "standard"
Lumincon parts? How do I ensure that main- and guiding scope point in the same
direction (maybe a foolish question, but I don't have a clue....!!)
Matt:
>If you are using an ST-4, then I recommend a flip mirror.
>Pocono sold a decent one until they went out of business.
Dear Matt,
yes, I will use my ST4 with this setup, and I thing a flip mirror will make live
much easier!!!! Thnaks for suggesting - I didn't think about this yet!
>I know you already have a guide scope, but if you have the back focus,
>you should consider a Lumicon Newtonian Easy Guider. IMO an OAG is
>harder to use than a guide scope, but it vastly reduces flexure problems
>and reduces weight.
I have heard that a OAG won't work with the R200SS (I've heard this a while ago
on one of the lists), do you have other information, does it work?
Herm:
>I use Losmandy dovetail rings mounted on a 10" long aluminum bar, I keep the
>rings on the guidescope all the time, then slide it on the dovetail plate
>mounted on the OTA.. I just got a digital camera and plant to take some
Ypictures of my setup.. early next week or so.
Dear Herm,
I would really appreciate if you could take some pics of your set-up,
looking to pictures sometimes clarifies more than a thousand words....
Is your 10" aluminum bar selfmade or a Lumicon,...,... one?
Mike:
>I have a similar setup. I use a homemade 8" F3.5 newtonian on a Losmandy
>G-11. I also use a Celestron 4" F10 refractor for a guidescope mounted in
>Losmandy rings and do the same that Herm does. I leave it mounted in the
>rings all the time and just slide it on and off a dovetail plate mounted on
>my OTA rings.
Dear Mike,
thanks for sending the direct link to your homepage (set-up)
Ghhhheeee - f/3.5, this is fast!!!
>I have to say I love the setup and have not encountered any major problems.
>My guidescope is longer than the 8"OTA and its not a problem. at least not
>that I know of <g>. Just make sure you keep your guidescope pointed as
>closely to your target as possible. The losmandy 3-point rings make it easy
>to find a guidestar.
Do you mean to point the guidescope as close to the target I am actually
photographing? How much "space" do I have between the actual target aimed in at
the main instrument and the guidescope?
>Matt also brings up a good point. I use a flip mirror with my autoguider for
>centering a guidestar on the chip. You might want to look into it. With this
>setup, finding and centering a guidestar is a breeze.
This definatly sounds like a good idea to me - thanks for pointing that out! I
didn't think of this before (using a OAG with my SCT this never came into my
mind!)
Thanks again for all your resonses, I'd never thought it would be that many:-)
If you find some time, I am looking forward to your replies,
clear skies,
Aike
http://www.geocities.com/astroike/index.htm
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