Quote:
Originally Posted by gregbradley
I've had a 12 inch RCOS and have a CDK17 which is a corrected Dall Kirkham.
I was a member of the Orion Optics Yahoo Forum and followed it for some time. Not sure what the status is now but at the time I was following it to follow progress on OO dall kirkhams they were really behind on production. There was one guy in Spain who finally got one and it had a problem with the corrector. I believe OO handled it promptly (they seem pretty responsive).
There was a German guy who ordered a 14 inch ODK and I think in the end he was happy but the scope took ages so I would check that out.
Firstly, guiding. Using a guide scope with a long focal length RC will be problematic. Guide scopes are OK up to about 1500mm. Beyond that you start to get problems with differential flexure meaning something bends slightly to do with the guide scope/guide camera and the main scope so the corrections are not 100% valid anymore. So you really want a through the scope type guiding solution. Off axis guiders are the usual solution for that or self guiding cameras like SBIG or their latest versions.
Planewave Instruments 12 inch CDK is a good scope. There was a scope called the Hyperion by a US maker. They had a backlog on delivery also but that was some time ago.
As mentioned by Paul there is also Deep Sky Instruments. Carbon fibre is really the go with RCs as at long focal length you don't want expansion and contraction issues. I find my CDK is quite good that way - the scope's focus does not change much over several nights. The RCOS was even better at that.
A smaller but powerful scope is the Takahashi BRC250. That is now called the CCA250. Built like a tank and a bit heavy but its F5 and I got a lot of good images out of it. It also works well with a KAF8300 chipped camera being F5 and 1260mm focal length.
I have no experience with the GSO RCs but there are plenty of super images from 10 inch RC owners.
One caution I would add for long focal length RC. You really need decent seeing to get the most out of an RC. You can do narrowband to overcome light pollution but bad seeing is another matter. Seeing is always an issue with imaging but it does not affect a Tak FSQ106ED hardly at all but at 2 or 3 metres it can make a big difference.
So one way of working out which scope is best for you is to look at various images others have produced a make a note of which ones you like the best. Then what equipment did they use. Then modify that with your budget first then your seeing and light pollution situation. Then you can make an informed choice.
Also talking from experience, it pays in the long run to get a smaller amount of high quality gear than getting cheaper gear, not being happy with it, taking a big loss selling it and then end up getting the better gear later on. Good gear often sells later for not much less than you pay for it. Especially now if the price is in US dollars and our dollar does fall further.
Greg.
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Hi Greg,
What you (and Paul) said makes sense. While price governs quality, there's no substitute for aperture and having been there and done that over the years, the Planewave, Orion UK, ASA, Officia Stellare and a host of international brands in the semi to pro fields, makes me think it's best as you said, check out what others use and what they have achieved then draw up one's conclusions there then then. I'm still buying Lotto tickets.. lol..
Thanks mate.
James (Jim)