Paul H. posted that RC's were intrinsically 'sharper' than Newtonians (!) . I couldn't let that one through to the keeper Sorry to have taken this thread off topic .
I only reponded because as usual you entered the thread with what about a Newtonian argument. The question was about the 10"RC not about putting a barlow on a Newtonian. Don't plead that you were only responding to my statement Mark; you in fact made the first statement which was designed to incite a response.
If Newtonians are so good, why is that nearly every major observatory has RC or CDK designs including Hubble. Aside from weight constraints it must be the best optical system for the job (that includes the practicalities of setting up a gigantic Newtonian) or else they would not spend millions upon millions on building them.
Hi Frank,
I bought one of the GSO 10" RC OTAs and got it just before Christmas.
I am personally very happy with it so far and although the collimation was way way out when it arrived it was quite easy to correct via the normal 3 collimation adjustment screws on the secondary mirror.
It has what I consider, a good quality, solid and stable focuser with a nice feel and a 10:1 fine focus adjustment.
Also included were three extension rings designed to screw directly onto back of the main mirror casting before the focuser.
The OTA also comes with 100mm wide Losmandy style dovetail bars mounted top and bottom on radius blocks and a simple but adaquate finder scope bracket.
Considering the price, I think I got a very good instrument, but I'm no expert and definately not qualified to make any kind of expert judjement.
One thing though, I does not have any documentation whatsoever and not even a label of any kind on the OTA. I think it's an F9.
Would I make any kind of recommendation?
Yes, I'm very happy with what I got for my money.
And, where else can you buy a 10" RC for under $3500 delivered to your door?
Cheers,
Luke
P.S. I have attached a photo of it on my EQ6.
I understand them to be F/8... Taking an image of a starfield and doing a plate solve will give you the answer to that question though...
Congrats on your new scope, It definitely looks the business.. I wish you all the best with it and look forward to some images!
Ps. Might I suggest removing anything that is not 100% required from the mount... It looks very heavily loaded in that image.. To get good results at this sort of focal length, you really want to minimize the amount of strain on the mount.
Luke thanks for being the first person in a five page thread to actually say yes I have one of these 10" RC's and I like it! Thanks also to the others with 8" GSO RC's for their pictures. Obviously the issue for most non owners is how come they are so cheap and why? What's, missing, wrong or otherwise with them. The conclusion seems to be mostly the focuser.
Like a lot of you I am in the situation of asking the question, My 10" SCT, 4" refractor etc is ok but would going to this telescope give me an edge? Based on the owners comments I think the answer is yes.
BTW I am using both an old 10" Meade SCT on a G11 and a Celestron C14 (30 years old) and I'm looking to trade up to an RC without breaking the bank.
I believe that some of the early 8" versions had poorer quality focusers but these have been greatly improved.
The body of the focuser on the 10"RC is about 110mm outside diameter and the draw tube is about 80mm outside diameter.
The draw tube slides along a stainless steel guide that also acts to help reduce unwanted movements.
The extension rings (the focuser is removed from the OTA and screws onto one or more of these when necessary) are 121mm outside diameter.
I couldn't see any unwanted movement when focusing at Prime Focus through a Meade DSI Pro 2 camera.
My opinion is that this is a stable and good quality focuser. I can't fault it. I can however understand that other more experienced people may have other opinions.
Cheers,
Luke
Last edited by Luke Bellani; 23-01-2010 at 03:42 PM.
Reason: opps that should read "I couldn't see"
With your camera it is very unlikely that you will see any problems with the standard focuser... The focuser on the 10" may well be a massive step up on the early 8" focuser, and even a step up on the revised 8" focuser? However I still don't think it would securely hold a 3 ~ 5kg camera setup... I might be wrong... But my experience of GSO focusers tells me that it wont..
I had an 8" GSO RC for a while, it was a nice scope.. the optics were superb when properly collimated... the focuser was a brilliant example of how not to make a focuser for an imaging scope... The current owner of my old GSO RC has since put a 2" FT focuser on it, and it is a very very capable imaging system..
I believe that the 10" will make a beautiful imaging scope.. I very much look forward to results...
I went out and bought the 10" RC today and it has been on the G11 for balancing purposes and it balances very well with an ED80 and 5D mark II on it.
Had to buy a second 21lb weight though as one was not enough. Still this shouldn't worry the G11.
I think the build quality of the OTA is very good. The baffling looks to be very dark and I can see no reflection spots.
The focuser has a very little play but seems to lock tight.
One thing though is that there is no safety screw on the bottom of the mounting plate. I had a friend tap one in after I got home. Now I feel a lot safer.
I am soooooo happy.
Guess what? There is a giant storm going through as I speak. It is shaking the whole house.
I hope it passes over before dark and leaves some nice skies.
Nope sorry Frank u done it now Just looked at the Sydney weather forcast. Storms tonight showers tomorrow.
Looking forward to these photo's just the equip i'm thinking of upgrading to.
Star collimation is the most successful way to collimate ones of these scopes... I found in the 8", using a Cheshire on the kitchen bench I was able to get the mirrors roughly aligned by eye, just making all the rings concentric... Then when I got under the stars, I defocused a star and tweaked the collimation in much the same fashion that you would collimate the standard SCT. Once the shadow of the secondary was central within the defocused star, I nipped the collimation bolts tight (again, much the same as you would with an SCT) re-checked the collimation then started imaging... All up it took about 20 minutes....
search for a guide to collimating an SCT and that will set you right mate.. If you can collimate a newtonian, you will laugh at how simple the SCT/RC is in comparison.. The only thing with the RC is that "Close" is not good enough. Collimation is of the utmost importance with the RC design.. With an SCT reduced to F/6.3, close collimation is generally good enough to get a decent image. with an RC **Perfect** collimation is generally the only way to get good looking stars. Don't let that phase you.. its easy enough. it just takes a little doing..
Long exposure imaging with a newtonian so you have it mounted on a sherman tank turret do you? What a crock it's so impractical as to be laughable. Climb a ladder to set up your camera 300 feet above the ground strap it down to stop the shaking coz the wind has exceeded 1 knot . Put it back in its dobsonian mount where it belongs.
What a crock it's so impractical as to be laughable. Climb a ladder to set up your camera 300 feet above the ground ( snip) Put it back in its dobsonian mount where it belongs.
An 8" F5 Newt tube is about 12" longer than the total length of an 8" RC with CCD camera set up behind .
That 12" makes a massive difference to torque around the pivot (wobble wobble wobble). You need the mount from hell to get it to work. The imaging train on an RC is about 4" thick whilst the newt is 8 inch's thick all the way to the end and it works as a big sail in the wind not to mention that a newt has to have a similar camera setup flapping in the breeze at the top of the tube. This and flex and the long moment as well as poor balance in the tube itself just make imaging too tedious to contemplate when there are easier ways to get the job done. These are my thoughts and experiences after trying to image with a newt. The difference stepping up to a cat made was similar to someone trying to image through a F15 Mak then an F6 apo. Yes apo's are for pussies but it certainly makes life easy and the results speak for themselves. Optically newts can be very good indeed but technically they have the same effect as haemorrhoids, you are really going to need some preperation H to sooth your sphincter. To me putting a newt on an EQ mount is going to be as effective as putting a cat on a dobsionian mount.
This thread is annoying. People expect a 2K tube to have a image ready focuser and optics as good as a RCOS. Sorry folks it ain't gonna happen. A decent focuser will cost you $500 + and with the extremely rare exception you are ALWAYS GOING TO HAVE TO BUY ONE so factor that into the cost. A dam fine imaging RC ready to go at 2.5K was unheard of 12 months ago so whats all the fuss about?. It is not hard to install the focuser, just screw off the old one and replace it with the new one. You have to do it everytime you pack the thing away anyhow, it's really not that hard.
hi Mark, if what you say is taken as correct and l'm not commenting one way or another, but if we cannot image with an 8" f/5 newtonian because of the issues you see as true then it is a massive slap in the face for mount manufacturers and an even bigger one for us for buying them.
I like Newts, and am dead keen to keep well clear of this fracas as I can see it going nowhere. Each has their own opinions and in the spirit of the original thread I reckon bury it.
Mick, there are two "Marks" here though, it may be beneficial to determine which one you are discussing this with.
Gary
Sorry to have taken this thread off topic .
Just looked at the Sydney weather forcast. Storms tonight showers tomorrow.
