Dual Scope Set Up

[gnomus]

Plan A was to spend some time getting to know my new Mesu mount - amassing a ton of data with my single scope set up. Of course, the weather had other ideas. I have decided, therefore, to bring forward the plans to set up both scopes in a side-by-side arrangement. The scopes are my Tak FSQ85 and my C8 Edge. I have an ST80 sitting atop the Tak at present which is used for guiding. I'm hoping that the Mesu will allow me to do some DSO imaging with the Edge, but for now it will be used primarily for planetary and lunar work.

I have never set up a dual rig before and I would be grateful for any tips, tricks and generally any things that I need to look out for. Tips as to how to go about balancing the set up would be especially appreciated.

I am about to order one of these ADM plates to allow for dual mounting.

Thanks in anticipation of your advice.

[Tinker1947]

Its not something i have planned, but like most things in Astro do it once and it becomes easy, just getting to know what way to do it......

[r3i]

I've got a couple of scopes side by side: a Star71 for wide field and then either my RC8 for longer FL work or a Skymax180 for visual.

The main thing is as you say achieving balance and this is done on 3 axes:

1. On RA where you balance the scopes with the counterweights.
2. On DEC, where you have the side by side bar horizontal and you'll need to carefully shift the bar left or right to balance the 2 scopes against each other
3. On DEC, where you have the side by side bar vertical and you need the shift one or both scopes forwards or backwards in the mount to get balance.

[Zakalwe]

I have an Altair 115mm triplet and the C11 mounted side-by-side on an ADM plate. It seems to work fine with the Mesu.

Balancing can be a bit tricky, especially as the Mesu isn't that free with the motors permanently engaged. However, it seems to work OK. Balance in RA first with the CW bar horizontal. Then work on the DEC.

Here's my setup slewing about. You can see how I've arranged the cabling, which with a dual mount, can mean a LOT of cables (they've undergone another round of tidying since this video was created and are a bit neater now).

I've mounted the guidescope in a dovetail, so I can swap it out for my Lunt solarscope, assuming the Sun ever shines again!

One thing to consider is the horizon limits. I've set mine for the DSO rig, but because the triplet is offset so much to counterbalance the heavier SCT, it means that the horizon file doesn't really work for the SCT. Mind you, it's a couple of mouse clicks to disable it.

I'm also not sure about the pointing model being usable on both scopes. If you were to use the SCT for DSO work then you'd probably need a seperate pointing model per OTA. Again, it'd be easy to swap between them in PointXP. You'd probably want to consider a SCT with mirror lockups too.

[gnomus]

Thanks all. It sounds like it is a little awkward balancing everything. I am not sure I would want to be having to do this on a regular basis. Stephen - when you take off the guide scope and put in the solar scope does this affect balance a great deal?

In addition to the ST80, I also have an ED80. I was planning on using the ED80 (with a Quark) for solar viewing/imaging. I wonder if it might make more sense to lose the ST80 and use the ED80 for guiding and for solar work. Does anyone do anything like this?

[Zakalwe]

It's pretty easy....just go about it methodically Steve.

Mounting the solarscope needs me to move one CW up the bar slightly...no great bother.

[gnomus]

I'm thinking also that the ED80 is f/7.5 vs the ST80 f/5. So the ED80 might not make a very good guide scope.

[r3i]

I'm thinking also that the ED80 is f/7.5 vs the ST80 f/5. So the ED80 might not make a very good guide scope.

I would have thought that you'd still be okay, I'm sure I recall guiding at F10 long ago with a Meade DSI.   What guide camera do you have?

[gnomus]

I use one of these ZWO ASI120 cameras. It works reasonably well, but I generally struggle to find a guide star that is greater than 10 SNR and that does not 'blow out' on the PHD2 graph. I do worry about the loss of aperture. The more I think about this, the more I think that I should have my Tak/ST80/C8 Edge rig and just set up my ED80 on the CGEM + tripod when I want to do solar work. I knew I should have built a second observatory!