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Some guidance - two scopes


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I have an ST102 and a HEQ5 (not Goto) but modded the controller so that I can auto-guide with it.

I want to do AP using my Canon 550D (not modded) afocal.

I read a recent review in the Sky@Night Magazine of the SW Evostar 80ED Pro which rated it very well for AP. I am thinking about buying one but,

1 Can I use my ST102 for guiding or should I get another 80mm OTA?

2 If I can (or should) use the ST102, how do I get both scopes on the mount (side by side) or should one be mounted on top of the other?

All of this is probably o no brainer for most but searching varios web sites has not produced an answer that I have understood nor do I trust my interpretation of what I have read.

Would appreciate some help here.

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Hello Dante.

Your 102 will be fine as the guidescope.

Side by side mounting is going to be easier, as if you have the scopes piggybacked, you have weight further out and will need more weight than in a SBS arrangement to counterbalance the setup due to having a longer lever arm.

The trick is to keep the weight as close to the mount as possible.

Cheers

Rob

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Dante,

On the offchance you are still unsure of a side by side mount arrangement, I've added a picture of the system.

The bar that carries the two cradles will attach to your HEQ5 saddle, and the crafles at either end will have your imaging scope in one, and the guiding scope in the other, The guidescope will be supported in two guifdescope rings which allow the scope to be targeted on a guidestar. The dovetail that holds the ringed guidescope fits in the other cradle, and the two instruments are thus side by side. The main scope will also require to be attached to a dovetail, probably with a pair of rings too.

As Rob said, adjustments in the positioning of the combination to facilitate balance is required.

Apologies if I am telling you something you already know.:)

Image taken from FLO's website.

Ron.

post-13213-133877607835_thumb.jpg

Edited by barkis
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Hi Dante - I also have a side-by-side setup using exactly that ADM bar. I use it with an ST102 to guide an Equinox 80 (and also intend having a go at using it to try and guide a Skymax 180 :)). The only thing I'd add is that with a side-by-side bar, you need to adopt a different process for balancing - Try THIS link...

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At short focal lengths, I don't find the need to use guidescope rings, as there's always a star in the FOV to guide on, and guidescope rings add the possibility of flexure, which you need to avoid. That said though, most do use rings and don't have any issues....I'm just very 'belt and braces' when it comes to this :)

Rob

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As above and Rob's comment. I prefer a fast guidescope 'bolted down' over expensive and flexure prone guide rings. In the event of not finding a guide star (which has yet to happen to me) I can always pivot the guide scope left or right by loosening the bolt that holds it down.

Olly

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Gentlemen thank you all for your responses to cries for help, they have been a great help.:)

RobH & AndyUK

So I can use my ST102 for guiding:D That's great news. I thought I would need to get another OTA for guiding and had considered the ST80 having a similar set up as MartinH.

Rob your comments re guidescope rings (echoed by ollypenrice) is a bit of a relief . Guide Scope rings £95 or thereabouts are expensive then there is the dual mounting bar £147. If I must spend then the mounting bar is what I need

MartinH I can't tell from your picture if the OTAs are side by side. In the picture they look piggybacked?

AndyUK

Bookmarked the link. It will certainly help when the time comes.

I will be buying the SW Evostar 80ED Pro (£499). The test on S@N rated it quite highly (O/All 90%) against the Meade Series 5000 80ED (91%) which I now find is nolonger manufactured being replaced by another scope using the same optics just a better packaage (£799) and still short of a couple of important items.

Again thanks for you help so far. Any comments regarding the SW 80ED Pro would be welcome.

Dante

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Gentlemen thank you all for your responses to cries for help, they have been a great help.:)

RobH & AndyUK

So I can use my ST102 for guiding:D That's great news. I thought I would need to get another OTA for guiding and had considered the ST80 having a similar set up as MartinH.

Rob your comments re guidescope rings (echoed by ollypenrice) is a bit of a relief . Guide Scope rings £95 or thereabouts are expensive then there is the dual mounting bar £147. If I must spend then the mounting bar is what I need

MartinH I can't tell from your picture if the OTAs are side by side. In the picture they look piggybacked?

AndyUK

Bookmarked the link. It will certainly help when the time comes.

I will be buying the SW Evostar 80ED Pro (£499). The test on S@N rated it quite highly (O/All 90%) against the Meade Series 5000 80ED (91%) which I now find is nolonger manufactured being replaced by another scope using the same optics just a better packaage (£799) and still short of a couple of important items.

Again thanks for you help so far. Any comments regarding the SW 80ED Pro would be welcome.

Dante

Given the multitude of fine images knocked out by ED80s no comment is needed! It is an astro imaging classic and a bargain.

Olly

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