C9.25 as a guide scope?!

[Johnboy2011]

Planning ahead what would be the best all round approach for DSO imaging with a C9.25 on an EQ6?

I'm thinking there are two options:

1) Use an OAG through the C9.25 with a 6.3FR, which seems pretty simple and light but not a great focal length for DSO?

2) Mount say an ED80 on a dovetail on the C9.25 and use the C9.25 as a guide scope?

It feels to me like option 2 is good as it should be within the weight limit of the EQ6 and the refractor would be good for DSO and the SCT for planetary giving a good all roung set up.

What do you think??!!

John

[riklaunim]

SCT has a moving mirror. If you guide via SCT the guider will correct for slight mirror shifts that won't apply to the refractor (thus the image from the refractor may be spoiled). And f/6.3 SCT is good for planetary nebulas and other smaller DSO

[philj]

Hi John I used to guide with my C11, yep:icon_eek: a C11 as guide scope, it worked a treat. I had a WO FD80 on ADM rings and imaged through that. No problems with mirror flop/shift. You only get that when slewing or if the scope is in a position where the weight may shift due to severe angle change during guiding. The former is no problem bevcause if your slewing your not imaging and the latter never bothered me because I planned my imaging of objects to avoid this.

I once tried an OAG but couldnt get used to it but that was just me I reckon, I had been used to a separate guide scope and had the ADM set up so I was used to that way of doing things.

Philj

[Johnboy2011]

Thanks chaps, my C9.25 does have an ADM dovetail already installed on top....

[jwr]

I think it's all about the targets you want to reach. I'm interested in the smaller, more obscure objects in the sky. To that end I'm using my C9.25 with an OAG. I've found it works well for my needs, especially combined with the f6.3 reducer.

When I want to image wider stuff I'll piggyback my DSLR and guide through the SCT.

James

[Merlin66]

I've used a ST80+QHY5 on the ADM bar to guide the C9.25 with the x0.63 reducer.

I also use a beamsplitter ( similar but easier than a OAG) 99% of the time to guide the C9.25 with the spectroscope.

Depending on the object being imaged etc an ED80 piggyback guided by the C9.25 (with the x0.63) would certainly work. The NEQ6 could handle that.

[Johnboy2011]

Thanks,

It seems the consensus is if I piggybacked an ED80 I could switch between the two for guiding depending on the target. I guess using the higher power of the SCT for targets like the ring nebula etc and the wider field of the refractor for larger targets?

It feels like I am missing something as this seems to tick most boxes in terms of set up! There must be a down side!

John

[ollypenrice]

Thanks,

It seems the consensus is if I piggybacked an ED80 I could switch between the two for guiding depending on the target. I guess using the higher power of the SCT for targets like the ring nebula etc and the wider field of the refractor for larger targets?

It feels like I am missing something as this seems to tick most boxes in terms of set up! There must be a down side!

John

No real down side. The slow long FL SCT is not great for finding guide stars and you will have to get everything right to get the EQ6 guiding well enough to image with the SCT but all these things are possible with care. Even with the dreadful tracking accuracy of my LX200 I could piggyback a small apo reliably for imaging.

Olly

[Johnboy2011]

Thanks Olly.

Any thoughts on which Apo is best to go for on a budget? The Skywatcher ED80 Pro seems well regarded and a good size/weight. Is F7.5 fast enough or would I have to invest in a focal reducer as well?