View Full Version here: : Gso rc10
26-05-2012, 04:49 PM
Been thinking of upgrading my 10" newt to something high quality for imaging. Been looking at meade SCT and GSO. Im thinking the carbon fibre RC 10". Can get it for $2700 Which i thought was not too bad Any advice on the quality of this scope or is there anything bettet in that price range?
26-05-2012, 07:07 PM
The main problem with the GSO RC is that it's difficult to collimate; both mirrors have to be lined up on the same optical axis, they both have collimation screws and the separation between them is critical. Collimation of the SCT is a doddle by comparison, but the SCT is harder to cool.
It seems that every consumer level scope has issues of one kind or another and you need to be confident you can deal with the problems of a particular design.
26-05-2012, 10:08 PM
Ok thank you. what is the difference between collimating the GSO RC, SCT and a newtonian. Is it that on the SCT design you cant use a laser the same way you would on a newt? What about optical quality of the GSO? Thanks.
26-05-2012, 11:27 PM
The best tool I've found for basic collimation of the RC10 is the Takahashi collimating scope. It gets you pretty close then you can collimate on an out of focus star to get really precise. It's not that difficult.
I'm happy with the results I'm getting from mine. The optics seem quite reasonable and it is great bang for the buck. There's an example of an image I took last weekend here: http://www.iceinspace.com.au/forum/showthread.php?t=91216
You might find accurate guiding tricky unless you use an off axis guider. There are people using guide scopes but it takes some work to get rid of flexure.
27-05-2012, 11:11 AM
From the "care and feeding" brochure for the RC's, you should rarely if ever have to adjust the primary. They give very in depth and precise instructions on adjusting the secondary.
I used an auto-collimator to check my new RC and it did the job nicely. :)
You can download the brochure from here.
27-05-2012, 11:29 AM
The GSO RC scopes are no more difficult to collimate than your average SCT, easier in fact as you don't have to deal with a moving mirror. Just point it at a bright star and off you go.
27-05-2012, 11:30 AM
Generally the secondary is the only element that needs adjusting on a SCT and collomation is done either on an artificial star or real star - rough collimation is quick to achieve then it's a matter of little tweaks to get the first diffraction ring even all the way around for perfect collimation. You can't use a laser for SCT collimation. Then there's the issue of getting the scope cooled; the vents on the EdgeHD help with cooling or you can use a Lymax cooler for a Meade.(there are other methods too).
I haven't owned the GSO RC but have seen many posts complaining about collimation difficulty - the collimation has to be really spot on due to the hyperboloid mirrors and you can't rely on the factory to have the mirror seperation correctly set. I've seen a couple of references to the Tak collimation scope making colllimation much easier so you may need to factor the cost of that into your buying decision Erik. Cooling is obviously much easier with the open tube. The GSO mirror quality seems to be decent.
27-05-2012, 11:40 AM
...... provided the scope arrives properly set up and you only need to adjust the secondary.
27-05-2012, 01:59 PM
The primary mirror is set and fixed in place at the factory so only the secondary can really be adjusted in any case and you should never try to move the primary unless you are well qualified . I agree if there is misalignment in the primary then you need to send it back as special equipment is needed to do this properly (there was a thread on this a few years ago when they were first released). My experience with these scopes is they are no more difficult to collimate then any other scope with an adjustable secondary mirror be that a newt or SCT.
28-05-2012, 10:03 AM
I recently acquired one of these and am very happy with it. I have not had to bother adjusting collimation yet (Bintel set it up right I think see the attached image). The main issue I had was with the stock focuser - for an imaging scope it was not strong (flex). As it turned out my focuser was faulty and the replacement a lot better. I have fitted a motor driven moonlite anyway as I have and SBig, FW and sometimes and AO8 on the back, it is a luxury but a nice one to have. You would most likely need to do something about the SCT focus as well for imaging as manual focusing is a pita.
My other commenet is you may need an FR - in which case the AP ccd67 is a good unit if you have a smallish ccd like mine.
28-05-2012, 05:34 PM
Thanks for the feedback guys. I was a bit concerned about the collimation, but from what I am reading it is not too bad. Also heard the focuser was not brilliant, I would like a motorised one anyway. I know what you mean about focusing being frustrating without one!
Nice images by the way.
I am still undecided though. I'll keep thinking for a bit and see how I go.
28-05-2012, 10:00 PM
As one of the leading advocates for the GSO RC series of scope let me give you some tips.
1. These scopes can be a little finicky to get perfect collimation but it only needs about a good hour to get it perfect.
2. The primary should not need collimaiton work, but the screws are there just in case.
3. These scopes cool down easily and have fans for cooling.
4. The design gives very sharp images.
5. The scope needs a good focusor. The factory one is not good but not great. Choice of focusor can be a significant addition in cost.
6. GSO does not make a dedicated reducer or flattener for this range of scopes. They have a general reducer/flattener but you need to search out a good quality field flattener.
7. Watch out for dew, it can be a pain on the secondary in dewy conditions.
Also owning several SCT's I can say this. Schmidts in my opinion are great for planetary work. You can take a look at my planetary images for confirmation of this if you like. These scopes can also be used for DSO work too. I have not seen much serious planetary work done with an RC and I suspect the contrast loss can be a problem due to the large secondary. On the other hand SCT's dew up endlessly and can be difficult to control dew and prevent tube currents from dew amelioration systems. Added to all this SCT's need to be used on a GEM rather than on a fork for best performance.
Making a choice of which scope to buy can be a bit daunting but each telescope has its strengths and weeknesses and in my opinion not one will suffice to do all jobs.
Good luck with your choice.
29-05-2012, 09:07 AM
Thanks for your informative response Paul. I think I will hang on to my Newtonian for now it has been giving me very good results after a few mods and tweaks. one of my main concerns with the RC10 is that the secondary obstruction is 44% I realise no one scope will do everything, I want to mainly concerntrate on DSO work. There are alot of options out there. some very expensive haha.
29-05-2012, 09:35 AM
I have a GSO 10" RC and I must say after collimation, just a tad off at this stage, I wondered how it would go as a planetary scope so I had a good look at Jupiter. I was greatly surprised considering the secondary obstruction, the views were better than just good. They were surprisingly good to great. I've been really pleased with this scope and would not hesitate to purchase again. At the moment I'm waiting for some time to do the final touch up on the collimation as it does have to be spot on for those great images.
29-05-2012, 10:06 AM
I had a night with a GSO 8" RC and the C8 side by side, and the planetary views were good through the GSO, but clearly better in the C8HD. We went back and forth quite a bit, and the C8 definitely outshined it for Saturn.
Didn't view any other planets with it on the night though, so it isn't much of a sample :)
I don't have much of a dew problem with my SCTs, I use a l-o-n-g homemade dewshield and don't use heaters and I am usually okay for most of the night.
I modified a hairdryer to run quietly and with less heat and use that for a few seconds on the rare occasions that I still need to de-dew the front plate without waking the neighbours.
29-05-2012, 11:55 AM
I have been looking at carbon fober newtonian astrographs. Very expensive and most way out of my pricerange, like $30000! One nice one which is not too pricy:
Dont know much about this scope but it looks good? Big apature and not too heavy. About $2000 i think if i converted correctly.
29-05-2012, 12:31 PM
The 10" without the FLI ATLAS, should wipe off $2500 off the allready expensive $8000!
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