Guidescope

[Asterix2020]

I have just bought an RC8. I currently have a ED80 and and 480mm focal length 60mm refractor as a guide scope, all on an EQ6 mount.

How should I set this up?
I could use the ED80 as a guidescope when imaging with the RC8, but can I use the RC8 to guide for the ED80? That way I don't need the 60mm scope at all.

Could I mount all 3 on the NEQ6 - probably only worth doing if I move to a permanent set up?

Or do I just continue to guide with the 60 mm refractor and put either the RC8 or the ED80 on the mount depending on what I want to use?

Also, I'm using a DBK21 to guide and I get a grey background with white stars in PHD. It seems to guide ok but it can be hard to find a star sometimes. I've tried the different camera modes (unknown, Y800 etc) and it doesn't seem to matter. The DBK21 came with red filter when I bought it second hand and I was told to use it when guiding but I can't seem to get any stars visible when I put it on. Any help?

[rogerco]

Another option you don't mention is to use an Off Axis Guider with the RC8 and just swap the guide camera over when you are imaging with the RC8. I am only just setting up my system (Celestron C8 rather than RC8, but otherwise the same setup). I think the EQ6 will run ok with all three but haven't tried it as yet only the ED80 + 60mm combo (which worked well).

I am told for the longer focal length scope you have to be very careful with flexture between the guide scope and imaging scope which the OAG prevents but at the cost of possibly making finding guide stars difficult (haven't tried mine yet so no experience there).

Happy guiding

[Asterix2020]

Thanks Roger. I will have a play and may end up getting an OAG.

[Paul Haese]

Using a guide scope on a 1625mm or great focal length is not recommended. You are better off using an AOG so you get round stars.

[Asterix2020]

Ok, so OAG would be best for imaging with the RC8. Could I also used the OAG on the RC8 to guide when imaging with the ED80. That way I can leav the ED80 and RC80 on the mount and not change things? Or would it be best to only have the RC8 on the mount when using it, and the ED80/Guidescope combination when using it?

[Asterix2020]

And what OAG and camera would be best for the RC8? I'm guessing the DBK21 I have is not sensitive enough?

[Paul Haese]

You could setup up both scopes on the one mount with the OAG and camera moving from scope to scope

[traveller]

Hi Paul (Asterix),
Not sure if you read two other related threads along the similar lines
http://www.iceinspace.com.au/forum/showthread.php?t=120347
and http://www.iceinspace.com.au/forum/showthread.php?t=120026
Bo

[Asterix2020]

Thanks Bo, I had read them as well. I decided what I think I should do, but I need some specifics.

I currently set up each session, but will be builing a ROR shortly, so I was hoping to just have it all set up once. But I may just decide swap between the ED80/guidescope and RC8/OAG setups depending on what I want to image. I could try the OAG on the ED80 but I don't know how it will attach, I have a Skywatcher 0.85x FF on there so not sure if there is enough back focus.

Anyway, I have a system that works for the ED80, so I really just need something for the RC8.

I am thinking a SX OAG and a ASI120mM or Lodestar. The ASI is cheaper. I have no idea who these connect.

So can someone recommend the exact things I need to fit an OAG (can be the SX or another one), and camera to the RC8? The more I read the more I'm getting confused.

[traveller]

Don't overlook QHY5L-II, the mono version has a very sensitive chip.
They come in 1.25 barrel fittings, so can fit into a "standard" OAG.
RE ED80, I use the Orion Flattener/Reducer attached to my DSLR and found that I can get focus around the 35mm mark on the drawtube.
Hope that helps.
Bo