No corrector plate, no coma (not that coma is an issue in the meade ACF/R/RCX line) they are lighter than an equally sized SCT (from memory) No glass elements in the optical system, a larger imaging circle (according to the specs) no moving mirrors... open tube design (scope reaches thermal equilibrium faster)
They have their downsides too.. the long back focus and huge secondary for starters... All in all is a matter of horses for courses.. The RC design generally yields tighter star images than an SCT, whilst for imaging this is important, visually its not that big a deal.. Imaging wise, the RC is **Technically/on paper** a superior design. I say Technically, on paper, because you're always going to get a few people burst into tears when you try to tell them that there is something better than what they have.. And also, it is a bit of a generalization... Not EVERY RC will be better than an SCT.. especially not in every possible situation.. However going purely by the numbers, the RC design (Not the GSO RC Design, the RC design in general) is a superior imaging setup.
The C9.25's are renowned for their sharp optics...
I'd like a good imaging newtonian too actually... an 8" F/4 would be nice, like the Vixen RS200SS.. or one of those super spiffy ASA N series newtonians... Fast is the key I think, however I wouldn't want to go too short a focal length... Something between 800 and 1000 would be the go...
Interesting. Peter - do you care to stop us speculating?
The short answer there are too many dealers in Oz trying to flog them.
The advertised Oz price at Radios-R-us (if you get my drift ) is pretty keen and unless there are a number (say five) individuals who are prepared to place a bulk order, (we can do a better price than the radio guys)...it's not worth my while.
Looking forward to seeing the 12" when it comes out.
I fully expect to pay for a good focusor and it will still be cheaper than some other brands out there.
I do need to get another CCD though as the small pixels I have with the QSI is not great for my star images.
One thing just keeps cropping up. Why do people think they should be getting a great focusor with this scope for such a cheap price. Go buy an RCOS and see how much that is at 10" and you have to pay for a focusor as well. Nearly every scope I have owned has to have a new focusor. The only two I have not had to buy one for is the Takahashi TSA and the Solarmax 60.
H the Newtonian is a nice fast scope with a wide field. It you want to image galaxies and smaller planetaries you need long focal length with no coma and you just don't get that from Newtonians. SCT's have the focal length but are no where near as sharp and have coma. Each scope should be considered as a tool. Wide field for doing large objects, long focal length for doing small objects.
Personally I love my little scope, only paid 2.5K for it and besides some teething problems it works fine for me. Don't really know what all the fuss is about sometimes. Imaging is expensive, the more you pay the better the gear you get.
hi Paul, to a point l see where you are coming from, however you must see the criticism of these scopes as valid complaints. they are advertised as imaging scopes yet the focuser is not up to scratch, why don't they just fit a unit that will do the job and charge accordingly and going by your own admission they would still be cheaper than a high end RC and the buyer would have a complete article straight out of the box.
we have seen substandard merchandise such as IMO Skywatcher mounts for years and the only way to change things is to let the manufacturers know we want a complete product that has been thoroughly researched and meets requirements. the internal modifications you made to your scope may be no big deal to you and me but for someone without the hands on skill who wants what they assume they paid for it is.
I agree with Mick on that... Whats stopping GSO from buying a bunch of FT focusers, fitting them to the RC standard and charging a bit more? It would be nice to one day buy a telescope that required no modification in order to use it for the task it was designed for... That said, I do also agree with Paul, No matter which way you look at it... It doesnt really matter if GSO fit it with an FT and charge more, or if you buy the scope and an FT and mate them yourself.. Changing a focuser on these scopes is as easy as turning a thread...
It does look like the 10" focuser is a lot sturdier than the 8 and 6" model (going by the image and the description of the focuser only) However I've not seen a standard focuser ever stand up to a serious imaging system.. I've also heard of an FT focuser sagging under a serious load.. So maybe its less a substandard focuser, and more people expecting a Ferrari on a Kia budget?
Yeah I can see your point Mick, but you often bring this up in these threads and you don't even own one of these scopes. It looks like you are gunning for a fight on this all the time. My Celestron C14 required a focusor, my ED80 did too, so too did my C9.25. Its just a fact of life that you don't seem to get a good focusor with mass produced scopes. I paid a lot more for two of those scopes than I did for the RC.
Yes it would be nice if they included a great focusor but they don't at present. Maybe one day.
The new scopes don't have the same reflections problem as I had on my scope. The one shown on CN I have that too if I am imaging a really bright star like Canopus. It is a problem with the CCD I think.
Anyway I am sure the new 10" will be every bit as good as the 8". Just don't expect all the bells and whistles for this small price.
ask yourself why l don't own one Paul, because you don't know what your getting. l'm not gunning for a fight in the slightest, if people don't point out the shortcomings of products then why would the manufacturers want to improve them. why are the current crop of focusers and baffles better than the last lot? because people made it known they were not happy.
The C9.25 new generation better coma corrected unit might be very good indeed (the older version was excellent anyway). Great planetary shots with this scope and of course no diffraction spikes. Lovely comprimise size and weight vs portability.
Not to detract from the 10 inch RC but they are still pretty new I guess. Perhaps as Alex says they will prove a better option overall but you wonder by how much.
Alex the GSO 10inch f5s are still quite portable and not too heavy and work out around 1200 fl if you are after a quick imaging newt. I really wish they would bring out a 10inch f4! There have been some great shots throught the skywatcher/GSO 10 inches.
H the Newtonian is a nice fast scope with a wide field. It you want to image galaxies and smaller planetaries you need long focal length with no coma and you just don't get that from Newtonians.
I don't understand why you guys don't just wack in a 2" 2X Barlow when you want F8-F10 imaging with a standard F4-F5 Newtonian. I would imagine that there would be no quality loss with a Televue Big barlow unit.
With GSO 10" F5 tubes at around $700 and $250 for the Barlow it makes for a very cost effective and versatile setup. Newtonian coma at F8-F10 will be almost invisible on modern CCD chips.
Newtonian coma at F8-F10 will be almost invisible on modern CCD chips.
MPCC if required. Having said that I believe one of the reasons why a person would consider the GSO RC, Vixen VMC or a SCT would be the size compared to Newt.
Placing my 10" Newt in the back seat is a project on its own each time I decide to head out to a dark site.
I am assuming a SCT/RC with a carry case would atleast save you some space portability wise. A small observation (No pun intended) but its worth considering.
Edit - Just wanted to add that Astro-Tech 10" RC (similar if not the same as the GSO) is listed as 2695 USD at Optcorp.
I don't understand why you guys don't just wack in a 2" 2X Barlow when you want F8-F10 imaging with a standard F4-F5 Newtonian.
That is because a Newtonian is not as sharp as an RC (my opinion and certainly many others) and a fast Newtonian is not always the answer Mark. Tools for the job.
Lever action alone makes it impractical for imaging. Not to mention flexure of the tube.
A Newtonian is not always going to be useful in all situations.
That is because a Newtonian is not as sharp as an RC (my opinion and certainly many others) and a fast Newtonian is not always the answer Mark. Tools for the job.
Could you elaborate on this statement , Paul. How so 'not as sharp' , on axis or off axis or both ?
Newtonians from my experience produce lovely images but all the really sharp hi res images come from either a RC or CDK. I see plenty nice wide field stuff with a Newtonian but never see any hi res stuff. This is the strength of the RC and CDK. You buy one of these for sharp hi res work and nothing more than that. The wide field well buy a Tak, AP (if you can stand the wait) or even a hi end Newtonian like ASA (if they ever get their act together with flexure).
It is purely an opinion but all the top imagers have this gear and that says a lot to me.
My 8" has it's good and bad points and I'm still not sure if I got an F8 or F9 but couldn't be bothered with the hassle of sending it back etc etc.
I'm still getting reflections depending on what I'm imaging although I'm yet to flock the primary baffle but I did repaint it with Krylon
It's handy easy too transport etc. I replaced the focuser with a Moonlite but I guess it probably wouldn't matter what focuser came with the scope there would be a better one and us gear freaks would want it regardless.
I've had some good and bad images using the scope, the bad one's more too do with me than the scope.
All scopes have there good and bad points and you'll all no doubt try varying types over the years
All in all the the GSO RC's do the job and if money is an issue and you like the idea of an RC then I'd recommend it even with it's flaws.
Newtonians from my experience produce lovely images but all the really sharp hi res images come from either a RC or CDK. I see plenty nice wide field stuff with a Newtonian but never see any hi res stuff.
Theres nothing from a theoretical perspective to back this up. Both designs are equally _sharp on axis_ assuming they have well made optics . With appropriate field flatteners and/or coma correctors each design can have superb off-performance.
Just for fun I ray-traced a stock standard 8" F8 RC design and an F8 Newt ( F4 barlowed ) to the corner of a flat 35mm `film ' field , without any auxiliary optics. See attached . The raytrace star spots are presented at the same scale and the white circle is the airy disc. The Newt is the one with the coma
Can you point to any websites of people doing long focal length work with Newtonians ? I would like to see the quality of their rig. I suspect that most of the quality work you see are instruments mounted on serious mounts . The first remotely decent shot I ever saw taken with an 8" F8 RC was when Peter Ward put the tube on his Paramount.
Hi Mark, interesting dicussion. I have barlowed x2 my f/5 newt (5"). My image scale dropped from 2.48 asp to approx. 1 asp. On axis details were suprisingly good. My optics are fairly average. I got loads of coma on the edges though. My barlow was a GSO x2 barlow. Would a televue powermate make a big difference with coma instead of a barlow?
) is pretty keen and unless there are a number (say five) individuals who are prepared to place a bulk order, (we can do a better price than the radio guys)...it's not worth my while.
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