ST80 as a guidescope

[RogerTheDodger]

Thinking about buying an ST80 to use as a guide scope with a webcam, but what else will I need? how do I mount it (cheaply) and will I need some sort of extension tube to get focus?

I'd be grateful for any opinions/info from people using the ST80 this way please.

roger

[Veracocha]

I see you have a 200pds?, then I would purchase a standard skywatcher dovetail bar and mount it on the opposite side of your rings. Then mount the ST80 on top of that. Not sure about using the webcam but for my guiding camera I needed an extension tube to get focus without the diagonal. A barlow with the lens removed acts as a good extension tube.

[Psychobilly]

My Synguider comes into focus using the barlow housing that comes with the OTA (lens removed) and the focuser racked out about 55mm...

[Dave Smith]

I just use a diagonal as the extension. It works fine.

Dave

[brantuk]

I mount mine on a side by side bar and leave the diagonal in too. The webcam (SPC900NC) is controlled by Phd (free) wich feeds tracking adjustments back to the mount. Everything goes through Ascom drivers (also free to download) including the imaging camera on the other scope.

[steppenwolf]

You will need an extension tube to achieve focus. I have used a diagonal as a last resort to gain the extra outwards focus although I can't recommend it as it can introduce differential flexure. Veracocha's mounting method is a good way to start as a low cost method.

[PH-R]

Hi, see this thread : http://stargazerslounge.com/beginners-help-advice/151937-st-80-focus-issue.html & this one : http://stargazerslounge.com/beginners-help-advice/83027-guiding-gurus-please-apply-autoguiding-help.html lots of helpful posts.

Best wishes,

PH-R

[RogerTheDodger]

Thanks all, that is a fantastic response and really useful

[Sam]

As mentioned probably the easiest way to do this is to get a dovetail bar to connect to the two tube rings that hold you 200mm scope onto the HEQ5. You will need two additional tube rings to attach the ST80 to the new dovetail bar. These tube rings will need to be larger than the scope as you will need to convert them to guidescope rings - this is basically where you drill three holes in each ring and six bolts then hold the ST80 in place. It means you can adjust the position of the ST80 very easily. Obviously you'll need to protect the surface of the ST80 from the ends of the bolts with some plastic or rubber. I originallly used some rubber tap washers which worked really well. The holes in the tube rings need to be threaded - the metal is very soft so it's quite easy to do. The attached picture is not very good but it'll give you the idea.

Sam

[Veracocha]

I did not go to the trouble of guiderings for the ST80. I opened out the bolt hole on the rear ring so that I have some lateral movement to play with. Rare indeed that I can't find a star in this way.

[Philmarriott]

Looking at getting this set up so thanks for posting

[Uhwaz]

i mounted mine on this http://www.teleskop-express.de/shop/product_info.php/info/p6479_TS-Piggyback-Cameraholder-for-1-25--Losmandy-Level-Counterweight-Shaft.html

helps with balance as i have EQ5

[RogerTheDodger]

Looking at getting this set up so thanks for posting

Glad it helped, I'm still using it now with the diagonal to get focus

[RichM63]

@Uhwaz, interesting concept. I too have an EQ5, any chance of a picture of your balanced full rig including the guide scope.

I'm trying to get my head into shape with the idea of the guide scope hanging off the bottom of the weight shaft, as this would have a reasonable effect on the overall loading of the mount in that counter weight side is not generally taken into account.

Any fixing issues to be wary of?

Guide scope crashing into tripod?

Cheers,

Rich

[Uhwaz]

sorry but no pic, scope has been parked for last couple months in shed as i have new baby in the house so no time for stargazing atm

i didnt have any problems with scope crashing into tripod 

make sure screw is tightened thats about it

shape is like H pretty much, where the middle line is your wieght shaft

hope that helps

[ChrisLX200]

As mentioned probably the easiest way to do this is to get a dovetail bar to connect to the two tube rings that hold you 200mm scope onto the HEQ5. You will need two additional tube rings to attach the ST80 to the new dovetail bar. These tube rings will need to be larger than the scope as you will need to convert them to guidescope rings - this is basically where you drill three holes in each ring and six bolts then hold the ST80 in place. It means you can adjust the position of the ST80 very easily. Obviously you'll need to protect the surface of the ST80 from the ends of the bolts with some plastic or rubber. I originallly used some rubber tap washers which worked really well. The holes in the tube rings need to be threaded - the metal is very soft so it's quite easy to do. The attached picture is not very good but it'll give you the idea.

Sam

I did something similar just today in order to mount my new SW 80. I don't really need guidescope rings I think because the FOV will be bright enough not to worry where it points, but at the moment the rings were all I had to hand.

ChrisH