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Looking for advice on guidescope or OAG?


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Just about the pull the trigger on an autoguiding setup but I still can't get my head around whether I want a guidescope (ST80) or OAG?

I understand the differences... or at least I think I do! Clearly, the guidescope is ultimately the better option. It can be pointed at stars outside the main scopes FOV and is likely to be able to resolve the dimmer stars for guiding (or is that just my impression?). The thing is that I will always be remote from my home and will always have to set up and break down and drive 10+ miles to my dark site. So I want to keep it as simple as possible.

If I accept that OAGs are not as good as a guidescope then the question is this: is an OAG going to work in most sitiations? Because if it is then it seems the better option for me. Having said that... I am happy to get the ST80 if it is significantly better but not if it is only a bit better... if you see what I mean. Money is not really an issue as an OAG is about the same price.

So what should I do?

EDIT:

Since posting I have done what I should have done and searched the forum properly! I am now convinced that the ST80 route is by far the better choice. OK, there is another scope to set up each time but OAGs are not the walk-in-the-park they might appear to be either, especially with a DSLR.

If you have any comments/advice then please go ahead and post anyway. Thanks.

Edited by Snaxmuppet
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I would have thought your best option would be to turn your ED80 finderscope into a guidescope by putting a guide camera in the back of it (with a small adapter).  This is really lightweight, can be mounted in a second and cheaper and lighter than using an ST80.  

I have used both, and the ST80 works well, but needs mounting in guide rings which need screwing on.  The fiinderscope can be used in the finderscope foot - easy peasy.

Additionally you don't lose your finderscope, you just have it on the laptop instead of bending and squatting in awkward positions.

To be honest I have read a number of threads where people have had difficulty getting the optimum distance and focus with an off-axis guider, plus additionally I wonder how guide stars can be seen if a narrowband filter is being used. 

HTH

Carole 

Edited by carastro
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Thanks Carole.

I have been searching for how I could convert my SW 9x50 finder scope to a guidescope but so far I haven't found anything. If anyone knows of a link to how to do this I'd really appreciate it.

I am looking to get a ZWO 120MC to use as my guide camera so I will need to be able to fit that to it.

Any help would be greatly appreciated :)

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I don;t know the guide camera you are planning to get, but Bern at Modern Astronomy sells adapters to convert the finderscope.  You just need to tell him which camera you are planning to use.  Though it might be a good idea to make sure he has an adapter for that particular camera before you buy the camera.  I know he stocks the adapters for the QHY cameras (I have a QHY5) and they are great guide cameras.  

Any particular reason for choosing this guide camera?

Carole 

Edited by carastro
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just something to try i use a finder with a webcam that has an old eye piece tube glued to it. and the finder has the back part unscrewed, in the place of the rear optics i use a insulating tape role and pushed it into the opening the cardboard tube in the tape is a nice tight fit for the eyepiece i used that till i made a better adapter.

the ccd/cmos chip needs to sit level with the back of the main finder body it actual worked a treat.

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This is a finder scope acting as a guide scope, it has a Modern Astronomy adapter screwed in where the eye piece goes, works quite well but not as good as a ST-80..

Finder scope with a Lodestar....

004GUIDESCOPEFINDERSCOPE.jpg

ST-80 with a Lodestar..

DSC_0190.jpg

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I have recently moved away from separate guide scopes started using Off Axis Guiding (OAG). You could buy an OAG assembly from E-bay for less than half the price of an ST80.

http://www.ebay.co.u...=item56743536f4

The trick with getting one of these OAG's cheap is to bid about £45. Even if you are outbid the seller 'Joy' always gives you a second chance offer at your bid price (I got two of these this way- even though 'winners' paid well over £50!).

Combined with a sensitive camera like the Lodestar X2 these cheap OAG's have doubled my trail free tracking to over 30 mins and I have been able to take some load off the mount by removing the guide scope altogether.

Setting up the OAG was easier than I expected - but you might struggle with a less sensitive guide camera?

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Thanks everyone.

I shall take a look at Modern Astronomy for the adapters. :)

To be honest Carole I am still deciding which camera to get for guiding and I have looked at most of the popular ones but the ZWO 120MC seems like a good choice for me as it is also a pretty good imaging camera for the solar system. The QHY5 is another good choice. I think this will just be down to personal preference.

As for doing anything with tape to make things fit... I am always so impressed when people make DIY things work. It shows initiative, imagination and requires skill to put it together. But it isn't me! I basically don't do DIY... not at home, work, hobbies or anything. The reason is that when I do it always costs me more than buying the right bits in the first place because I always mess it up :o So I will buy adapters designed specifically for the job or do something else. Sorry toxic, but that is just not me. :)

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I only have good things to say about the ST-80, I bought it as a guide scope but it tends to be pulled out and used as a grab n go for those quick looks when I do not have time to set all my other gear up for a full session.

I love that little scope, for the price it is great.

For keeping weight down though I would go with a finder guider, I did look at buying the adapter to convert one of my finders but found a second hand Orion one on ABS for not too much more than the adapter  cost so always worth checking there first.

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  • 2 weeks later...

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