Thread: Gso rc10
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Old 11-12-2011, 09:28 PM
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ReaPerMan (Paul)
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Originally Posted by JohnH View Post
I am thinking of getting a CF 10" RC for imaging with my AO-8/CFW8/ST2000xm/Losmandy G11G but I have some concerns and would appreciate some advice before I take the plunge.

1. Is this setup a good combiation for DSO imaging? I am in semi dark skies - the outer suburbs of Sydney - can see the Mway on a no moon night quite well...

2. Is the stock 3" focuser sufficient or should I plan on upgrading it
immediately? Will I need to refocus on filter changes - even if my filters claim to be parfocal? If the CF tube stable thermally such that I will not need to refocus due to thermal effects? Typical dusk/dawn delta T is 10C in my location.

3. I am not mechanically adept and am concerned about a couple of issus with this design of scope - the inital setup/collimation (I can ask the supplier to do that). But ongoing how frequently will collimation need to be tweaked? Not to happy with the idea of having to shim focusers or tune mirror separation. Are these scopes set/forget of in need of regular care and attention?

4. Will I need a FF given my ccd is not too large and if yes which unit is

5. I beleive these units have plenty of backfocus - so my imaging train should be ok - true? Would the FF make any difference?

Is there a better option for the money? I have had a VC200L in the past and was not overly impressed with it, but need a bit more light gathering power than the ED127 I am using today.
1. I have just purchased my GSO RC10CF and I am getting things ironed out to get the best of it. I am in the suburbs of Perth and I can get very good pics even with light pollution in the area.

2. The stock focuser has been improved in the latest models and if all you were using was a DSLR it would be fine. Heavier imaging trains need the change over to better focusers. The choices range from Atlas and the like (sell a kidney but worth every penny) to Feathertouch (expensive when optioned up built like a brick s***house and ultra reliable, a standard option at many overseas sales sites like altair astro!) or there is moonlight (well made cost effective <$500 for fully motorised, well respected all round).
refocusing on filter changes etc will depend on your filters. Checking focus after hours of imaging is good practice. I've only had my RC10CF for a short while and I have not had to refocus all night as when I checked it had held for the entire time. I have not had it over winter where my C9.95 seemed to change every couple of hours.

3. Collimation is a biggy here for RC scopes and needs careful attention as they are really picky. There are a number of threads here and the ultimate answer is the TAK collimation scope be aware that it's 2.7" and you will need adapters to suit. You can collimate without the TAK scope and there are a number of guides to help, please read the forum posts as some of them are very helpful but 'BACKWARDS!!' can get very confusing when following the guide and it's getting worse not better. Once collimated they hold well but the usual cavet applies to rough handling.

4 & 5. They still can use a FF and I am running the Astrotech 2" FF which works well with these scopes. It's 2" so if you go the wider route (2.7" etc) this won't be any good for you. Greg mentioned LEO's pics and they are indeed really good. He has a slightly slightly smaller chip and he uses the Astro Physics CCD tele compressor CCDT67 - 0.67x Reducer
this has a 22mm full circle at 0.67 reduction at 101mm. I use a QHY10 which is a full APS sized chip so this combination would give me viginetting. There is another suitable FF reducer from astro physics but it's number escapes me. Ricks is using it on his RC and it's a 2.7" connection.

Set up right there are many good pics from these scopes. Greg mentioned reflections in the baffel tube but this was supposed to have been addressed in the new models and I have not seen it with mine yet. Paul Hase had one of the earlier models and there is a comprehensive guide on his web site on how to flock the tube. As Brendan said these have a narrow field of view and are for giving detail or hunting out small targets. This can be improved with the FF/FR as in the case of Leo's pics.

All up I'm happy with my one even though the weather gods have punished me mightily for buying it!!

Good luck

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