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Guidescope Mounting and Testing

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Hi, I'm hoping someone can advise me please. I purchased a dual-mounting bar so that I could try to guide a camera and lens combination. The guidescope I'm using is an ST-80, somewhat naively I expected it would bolt together with a standard dovetail bar. :) This is what I have:


(The blue-tac is here so I easily attach a laser pointer.) Of course, none of the mounting holes in the ST-80 match up with the dovetail. I've bodged it together for now but it's held together with a single screw, which isn't ideal. Would a slotted dovetail solve this problem or is there something else I could use?

The forecast for the next week or two is looking pretty dire. My other question is would it be worth trying to guide on a light on the horizon as a test? I've had guiding going briefly a couple times, the best I managed was a 4 minute sub before PHD bombed out with a 'star lost' message, despite it having a very high SNR of 300 or so.

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Is it possible to turn that dovetail bar on the ST80 over so that it can engage directly in the one of the double bar's slots?

I must admit my ST80 doesn't have that and I resorted to tube rings and the 'special' ST80 dovetail bar.  This then gets engaged directly on the mount while the camera then gets mounted on top of the tube rings.   

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Hi Dave, this is what I have been using, it's a dual saddle with a guider for the ST80, this allows the ST80 to be pointing at the same target.








Sorry tried to delete some photo but for some reason can't :(

Edited by JimT
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Thanks for the suggestions.

8 hours ago, Davey-T said:

ST80 generally comes with tube rings which would bolt to your dovetail.


It was previously fitted to an ED120 using tube rings but unfortunately they are threaded differently to the dovetail.

8 hours ago, almcl said:

Is it possible to turn that dovetail bar on the ST80 over so that it can engage directly in the one of the double bar's slots?

Nice idea, but unfortunately the bar already attached to the ST-80 is too wide for my dual mounting bar.

8 hours ago, Davey-T said:

These are the ones that come with it normally, the 90mm ones.

Dave :icon_santa:


That could do the trick thanks, I take it those bolts will fit through the dovetail?

Alternatively, would this work?


Edited by Knight of Clear Skies
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I rebuildning my setup. Earlier I had a off-axis guider, but to expensive in the needed dimension for the new setup so I came back with a separate guidescope.

When I mount the guide scope I have the guidescopes tube rings attached to the main telescopes tube rings, they are ready for this. I try to have it very stable and as close to RA axis as possiblie, that's way the guide telescope is not mounted on top of the main telescope.

Here I have some photos of it:



I think it will be more stable than a double montage on the Vixen style tale.

Just some ideas.



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