Richey-Chretien Astrographs

[pjphilli]

Hi
I notice that Lee Andrew has Richey-Chretien astrographs at very attractive prices. I am considering getting an RC-8in f8 for use with my DSI2 and Canon 400D imaging cameras. However, I would like some advice from those who have had experience with this type of scope, especially:
1. Would the above scope be suitable for use with my guiding cameras?
2. I understand that there are some issues with the focuser and focuser travel with R-C scopes - if so what are they?
3. Could focal reducers be used with an R-C (focuser travel?)
4. How does the weight of an R-C compare with a comparable Schmidt-Cassegrain scopes?
5. Any other comments?
Cheers Peter

[Paul Haese]

1. Not knowing that guide camera, I will hazard a guess and say it should work fine.

2. The new focusor appears to be better than the previous version, but like any scope I always buy a better version if needed. I bought the Feather Touch and this sorted out a lot of the problems with slop in the focusor.

3. Focal reducers could be used but you would need to find the correct one for the job. GSO as yet has not made a focal reducer specifically for the telescope. At least that is what I have been told from the manufacturer. So hunting around a bit might be needed to find what you need. Although why anyone would want to put a reducer on a long focal length scope is beyond me. One buys the long focal length for the narrow field of view and magnified view of distance objects.

4. The RC is much lighter than the SCT of same size when you buy the carbon fibre tubed version.

5. As far as I am concerned these are a great scope for the money. Check out my DSO section on my site for images taken with this scope.

[pmrid]

Peter,
I agree with Paul. The DSIII should be no problem. Are you using a guide scope or off-axis guider. I've used both with a GSO RC and both work fine.
The focuser supplied is not up to imaging standards but a feather-touch with motorised focuser is the duck's guts with these.
Contact Ron at Sirius Optics (http://www.sirius-optics.com.au/ (http://www.sirius-optics.com.au/) email to soptics@bigpond.net.au. They're at Underwood, Qld, Australia 4119
Phone: 61 7 3423 2355, Fax: 61 7 3423 2366) I know he has a second-hand RC 8" with a feather-touch and a JMI motofocus on it for sale.
Peter

[pjphilli]

Thanks Paul and Peter for your replies.
I use both Meade DSI2 and Canon 400D for imaging and a QHY5 camera on a guide scope for guiding. Yes Paul, although I have used focal reducers with the small chip DSI2 the large chip of the Canon 400D would probably not need a focal reducer. I also have a Meade 80mm f6 apo refractor for my wide fovs anyway.
Thank you both for the further information and I will follow up on your suggested sites.
Cheers Peter