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Need a guidescope for SCT 9.25


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Can anyone recommend a decent guidescope set up for a Celestron c9.25 on eq6pro.

I have no obvious view of Polaris and I really need a guide scope to move my set up forward. It will be a bonus to not have to use a laptop to guide and I have looked at Skywatchers and Celestrons stand alone guide cameras. I have also looked at Orion and Optic star packages.

Any experience or suggestions would be helpful as this is a mindfield, I thinks.

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It is not everybody's cup of tea but the Baader Vario Finder could be your answer. It is small and lightweight and quite versatile so won't tip the scales on your 9.25 and can also be adapted for purposes other than guiding/finding. I was going to get one myself to swap the finder on my CPC 1100 but have decided to go for a larger APO refractor unit as the 1100 has the real estate to piggy back one. I don't really know how much extra weight you can pile onto an EQ6Pro but with the heavy SCT and probably some weighty photography kit, a small scope like the vario would be ideal to keep weight down. There are varoius guide systems that can be incorporated with it so most budgets can be catered for. I'd be interested to hear what you finally plump for...

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I have a Baader vario finder and it's rubbish for the money, it's been back to Baader and they made a special selection for me and I am still not happy. With the spider it costs 360 Euros which for what it is a lot of money. If I however change the diagonal and the eyepiece it came with one of my own, it is fine, but you should not have to do things like that. All TS said was it was good enough for a finder, what sort of after sales service is that.

There are some good guide package out there, I don't even think you need top quality optics I would go for something about 80mm and as fast as you can get, CA is not a problem to a guider. I have the Lacerta stand alone guider, one day I will try to use it.

Alan.

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A couple of things keep coming up on reviews for stand alone guiders. First is that the view window is limited and 2nd that they struggle with star lock. I guess im going to have to take a pick. i havnt heard of Lacerta ? I understand the comment regarding fast optics, however, I think I need to be careful here due to relatively slow C9.25 ?

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I've heard it said that it's better to guide an SCT with an OAG because it's tricky to guide a long focal length scope with a short focal length guidescope, and because it will (hopefully) correct for mirror movement.

I've never tried guided imaging with an SCT though, so I can't speak from experience.

James

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I image with an ODK14, a Cassegrain variant, and would say without doubt that you need an OAG. The relative focal lengths of a small guidescope and long SCT are too mis matched and mirror shift can get you. Go for an OAG.

I'd also say avoid standalone guiders. They look like a solution but they can easily turn into a problem.

Olly

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  • 5 weeks later...

Thanks Olly. I have not looked at OAGs at all and not really sure where to start. Please, give me a clue where to start on these and I will have aa look and let you know how I get on.

I'd be interested to hear how you get on with this...
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I've been succesful using a finderguider on my C9.25 when used with the 0.63 focal reducer but that is really borderline. At F10 it has only worked once without producing egg-shaped stars. But that scope has a really neglible mirror shift (compared to my C14 that has a huge mirror shift with its big heavy mirror). An OAG is definitely the best choice but also introduces the hassle of finding a guide star which is always difficult with hign F-numbers. Especially if you are in a light polluted area.

A 400 mm Skywatcher ST80 solidly mounted to the main scope is a good choice if you don't want to go the OAG route.

/Lars

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The Altair finder guider is a nice little tool. Very light and highly adjustable with a 60mm doublet aperture - and it fits very nicely in the SW/Orion Sct shoe. You can pop a Telrad on the scope for finding stuff in place of the regular finder. Otherwise an OAG - the Celestron one is pricey but adjustable. :)

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The Altair finder guider is a nice little tool. Very light and highly adjustable with a 60mm doublet aperture - and it fits very nicely in the SW/Orion Sct shoe. You can pop a Telrad on the scope for finding stuff in place of the regular finder. Otherwise an OAG - the Celestron one is pricey but adjustable. :)

I have an Altair solution with a QHY5 in the back and can strongly recommend although I've yet to use it with an SCT.

I'm picking my c9.25 up on Friday so shall be interested to follow this. I'm thinking I shall eventually go OAG with a reducer, but this will need more funds so may try without OAG at the start.

Typed by me, using fumms...

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These little finder guiders would amaze me if they'd reliably guide an SCT. Their FLs are so short that I don't see them keeping a long FL imaging scope at sub pixel accuracy.

TS do a finder guider. I can't recommend the Starlight Xpress one because it allows the camera to rock on its lock screw which forms an excellent pivot! I had to make a triangulating brace from guide cam top to imaging camera to keep it still. How bad is that?

Imaging with an SCT is never going to be easy. Give yourself a chance with an OAG which is guiding at the same FL through the same light cone.

Olly

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These little finder guiders would amaze me if they'd reliably guide an SCT. Their FLs are so short that I don't see them keeping a long FL imaging scope at sub pixel accuracy.

TS do a finder guider. I can't recommend the Starlight Xpress one because it allows the camera to rock on its lock screw which forms an excellent pivot! I had to make a triangulating brace from guide cam top to imaging camera to keep it still. How bad is that?

Imaging with an SCT is never going to be easy. Give yourself a chance with an OAG which is guiding at the same FL through the same light cone.

Olly

All good points, well made.

I had intended to use a reducer when I get round to imaging with it and shall move to OAG when I have funds. My objective is to mount an 80mm frac on top of the 9.25 to use for imaging with the guide scope guiding the frac. This is all I'm my bid to make it a set up that never comes off.

Funds allowing of course, as a chat with Bern highlighted ASA reducers, Baader Clicklocks, dovetails etc. which will be required in the end, as well as an OAG.

Gulp.....££££££

Typed by me, using fumms...

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Sorry but in my post I said TS do a finder guider when I meant to say that they do an OAG. Senior moment - again!

I had expected the OAG to be a bit of a pain on the 14 inch but accepted that it would be necessary. In fact it's OK. Just occasionally we struggle to find a star without displacing the scope. That's in the Spring galaxy season out of the plane of the MW. Closer to the MW it is always possible but a sensitive guide cam is vital with an OAG.

Olly

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I have Meade 10" SCT on wedge/fork mount :shocked: and guide with piggybacked f/9 80mm refractor at PF and 100mm f/6 with 6.3f/r . The 100mm refractor combo is good because as you say you can swop guider and

camera between scopes without stripping everything down.

I tried OAG with Atik OAG but gave up as I was spending more time trying to find a guide star than imaging. Have resolved to try OAG again when we have some clear skies to waste.

Dave

Forgot to say I use Orion SSAG but you need laptop

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