Attaching guidescope to f/10 SCT - advice please!

[x6gas]

Hi all,

I have searched the SGL forums and found some advice, but I wonder if I can pick your brains about autoguding set-up for my f/10 SCT.

Firstly, I know that autoguiding at f/10 is very challenging and I suspect I will be getting a focal reducer at some point. I also understand that OAG is mentioned a lot. However, I just want to ask about autoguiding using a seperate guidescope (ST80) on this system.

Basic question is the best way of attaching the guidescope to the set-up.

As far as I can tell the options are:

1) ADM Mini-dovetail attached to front of scope

2) Full-length accessory bar with guiderings mounted on that

3) Dual mounting bar

4) Mounting on the counterweight bar (I've no idea how this would work in practice)

Have I missed any other options? I can't see how option 4 would work and now I have the 'scope I am really unsure about the dual mounting bar option.

It'll be a little while before I am imaging with this set-up, but I'd be interested in thoughts on the best solution.

Or should I really be looking at the OAG option after all?

Thanks in advance for any discussion!

[riklaunim]

If you can - use OAG. External guide scope would have to be rock solid mounted to the SCT to avoid any flextures/bending that would spoil the guiding.

[cgarry]

I have used an ST80 with my C9.25, mounted with a dual mounting bar. Although it mostly worked I found it a real faff to set up.

I now use an OAG which is far simpler to set up and produces better guiding. I have never tried without a focal reducer though.

Cheers,

Chris

[Psychobilly]

Once you have the OAG setup it also takes seconds to move it between scopes and your off to go again...

[Mr Spock]

I have ADM mini dovetail with 125mm rings and an 80ED. Works perfectly!

Plus if I don't need the 80ED it just slides off the mini dovetail leaving the scope as is

[Merlin66]

I have a set up like Spock. An ADM minirail on top of the scope and rings/ clamps to hold the ST80/ guide camera.

[x6gas]

Thanks for the replies.

Now I am torn between the ADM minirail system and the OAG!

I'm more used to the seperate guidescope route because that's what I am more used to...

With respect to the ADM minirail:

It's this system, right?

Does the minirail run the entire length of the scope and secure at both ends?

I assume that 125mm rings are best for the ST80?

Thanks again!

[x6gas]

Incidentally, do plan to use the synguider with the set up. I see a discussion on the Atik OAG saying that this should be alright but anyone actually using a largish app. SCT, Atik OAG and synguider?

Cheers, Ian

[Merlin66]

Yes,

The ADM rail goes all the way from the rear cell to the front.

125mm rings are good.

If you do go down the OAG route (nothing wrong with that...) don't buy the Meade version of the OAG! Rubbish. The Celestron Radial Guider is pretty good. I don't like the narrow TS version (yet.....)

HTH