Quote:
Originally Posted by ausastronomer
Hi Greg,
I can't agree with this comment at all.
There are a whole lot of reasons why someone might choose a SCT as their scope of choice for visual astronomy, including convenience, lack of storage space, or dual purpose as an imaging platform.
The quality of the views isn't a reason anyone would choose a SCT, unless they don't know what they are looking at. Look at all the specialist visual lunar/planetary observers, look at all the specialist double star observers, look at all the specialist variable star observers, look at all the specialist deep sky observers, you will be lucky if you find any of them using a SCT for visual work.
The pure physics of the design precludes them from being the optical equal of a newtonian or a refractor.
1) Large Central Obstruction
2) Closed tube design with corrector plate hinders fast cooling
3) More air to glass surfaces introduces additional aberrations and light loss.
4) The optical quality of the scopes themselves in many cases is poor. Although there are a few good ones. I just haven't seen very many.
Mark,
If you don't plan on imaging in the foreseable future I would be giving serious consideration to downsizing your current 12" newtonian to a 10" and being done with it. Sell the 12" on IIS and buy a 10". There isn't a huge difference in the views, but there is an enormous difference in portabality, particularly if you went with a collapsible tube version. A 10" newtonian is going to be a better visual scope on just about every single target as compared to a SCT or RC.
If you do plan on imaging one of the Advanced Come Free scopes would be a good choice as an "allrounder".
Cheers,
John B
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I keep seeing all these reasons why newts give better images than SCTs, but a lot of those disadvantages don't play out in actual use.
You do want to have cooling for the SCT, mine gets down to ambient in under 20 minutes with the fans.
The light-loss is a bit of a furfy, I challenge anyone to show any noticeable light-loss from a current model coated SCT vs a same diameter newtonian. Side by side I have never found anyone that can discern a feature in a similar diameter Newt that is not as clear in my SCT.
There are more than 'a few good ones' but like many dobs and SCTs a lot of people don't collimate theirs properly. This will make any scope appear to be a poor performer.
The optical quality in some dobs are poor, the optical quality in some SCTs are poor. Whichever scope you buy, get a star test done. The optics in my C9.25 HD test excellently and it is a joy to look through and to image with. I've owned a VC200L before, and they are also a good scope.
But if I ould only have one scope (which is what has happened now) I would go the SCT... and I did
Whatever you buy, make sure the optics are decent, and if they aren't, then take it back.