Guidescope

[marxy]

Hey everyone.

Over the winter I had some dabbling missions into the world of astrophotography. I enjoyed setting up the mount - drift aligning etc just felt like I was actually observing instead of just clicking on a computer screen to achieve auto focus, auto tracking etc.

Thing is that I would like to add a small guide scope so that I can try manual guiding.

My imaging scope is a SkyWatcher 80ED and I'm using a celestron cg-5 mount with dual drives (non-goto since star hopping can be fun - sometimes )

I have read that my guide scope should have a longer focal length than my imaging scope which is at 600mm, so was considering another 80mm scope with a barlow which would give me about 1,100mm or so.

Does anyone have a suggestion for a good scope for this? I prefer cheap and cheerful since this will be my third scope and won't be used except for guiding.

Also, I've now got a Celestron C8 but I don't want to add it to the 80ED when imaging since I think that this will be slightly too high weight for the mount and I don't want to overload it!

Would I be crazy to consider an off axis guider? This celestron looks quite nice but I have thought about issues of brightness of guide star and focusing it. Celestron Off-Axis Guider — The Widescreen Centre

Finally, if using an 80mm scope for guiding will the AC694 Gemini side by side mounting bars be the way to go?

Thanks for all pointers and help,

Jay

[Merlin66]

Although you mention manual guiding, I don't recommend it!

I used to manually guide 20min exposures with an OM-1 film camera, and it was pretty painfull!

You would need a focal length roughly x3 the imaging scope and an illuminated cross-hair eyepiece and fine controls on RA and Dec.

A ST-80 with a x4 Barlow and a 12.5 guide eyepiece would come close to your needs. Its a lightweight solution and can be "converted" to use with a guide camera ( QHY5 etc) by removing the Barlow..

I've also got ( and sometimes use) a Celestron OAG. It's one of the best around but usually has a SCT front end; no big deal you can get a 2" to SCT adaptor and use it on the ED80 etc.

You'll need a bit of practise ( Oh, and a x2.5 or x3 Barlow - remember the focal length issue!) but it worked for thousands of amateurs over the years!

Hope this helps.

The dual bar works well; I had a Genesis 4" f5 side by side with a Meade 6" f3.6 Cometracker on an HEQ5pro...

[marxy]

Merlin,

I want to manual guide since I do NOT like to take out a computer into the field and this also means that I am completely not reliant on having a powerpack (my mount runs on batteries )

I saw the LVI standalone guider but I want to wait until people have more exprience with it.

Maybe at f/7.5 I can get roughly 60 seconds unguided if I'm lucky - leaves me with the brighter objects but then again, in the city it is hard to see ANYTHING without sky glow

[Merlin66]

An ST-4 ( still a few around) would be another good option.

If its good enough to guide the 48" Schmidt it's probably OK for an ED80!!. Just needs a bit of 12V power and it'll grab any ol' star image and hold on for grim death. Easy to interface with your mounting..

( As you can see from my sig. panel - I have one!)

[marxy]

I've seen there is one for sale at 350 pounds atm from ian king. I'm not sure about it since I've never seen how one is used before.

Still leaves me with the requirement for a second guide scope ASWELL as a new mount with an autoguider port! (mine is just the basic dual drive version with no computer guiding ports)

Does this change everything?

[Merlin66]

The ST-4 really doesn't need a computer controlled scope, it has inbuilt relays which function like the buttons on your hand-paddle; so if you can by-pass your handle-paddle you can interface something like the ST-4 ( At one stage I had to cut the PCB inside the handcontroller for a LX5 scope to get the guide signals into the system- it worked very well!)

You don't need a new scope but you would need an OAG or similar....