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Old 04-08-2015, 05:37 PM
garymck (Gary)
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20" RC heads up

Andrews has on their GS page a 20" RC to be avaiolable November.....

Price?

Mount - think it would fit on my G11? :-)

cheers
Gary
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Old 04-08-2015, 06:15 PM
glend (Glen)
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I was worried about some of the collimation issues with the smalller ones, until I looked through the details on Teleskop-Express - the focuser is de-coupled from the mirror carrier and separately collimatible. So I have rescrinded by concerns here with an edit.

Last edited by glend; 06-08-2015 at 06:35 PM.
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Old 04-08-2015, 06:31 PM
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Somnium (Aidan)
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20" ... wow, it is probably going to weigh somewhere in the order of 50kgs. GSO keep on upping their RC aperture, you wonder how far they will go. i am yet to see some images from these big RCs, Paul uses the 12" and gets great results. i have been considering, for some time, the combo of the EQ8 and the RC14 but haven't pulled the trigger yet. 20" though ... we are definately experiencing a new era of amateur astronomy.
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Old 04-08-2015, 09:27 PM
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g__day (Matthew)
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What would you mount it on? Will it come out with an EQ10?
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Old 05-08-2015, 10:59 AM
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rustigsmed (Russell)
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that is really getting pretty big, really big.
there is a guy in Italy using an EQ8 and RC 16" I haven't heard of anyone going any larger with the EQ8, perhaps you could get away with an 18" newt (with its lesser FL) but yes I think its heading to the serious mount territory... at 20"

TS has it on sale for about 5000 euro more than the 16"
http://www.teleskop-express.de/shop/...russ-tube.html
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Old 05-08-2015, 12:28 PM
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rmuhlack (Richard)
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What camera would you pair it with to get a useable image scale? at f8 that's a lot of focal length. Surely adaptive optics would be a must.
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Old 05-08-2015, 02:01 PM
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14,000 Euros would make it about AUD$27,000 landed. Hardly bang for your buck. There would be far better alternatives. They should hold off on the larger RCs until its completely certain their scopes are fully matured as designs and not a work in progress for someone else to complete. Unless the Aussie price is lower as that was Europe and they tend to have higher prices than we do.

$27K though puts it up against some seriously good scopes. TOA150 setup, AP140/155 both with a good camera, Planewave CDK 14 or its competitors IDK and Officina Stellare may start around there. FSQ130 and a good camera.

Add on a large mount to handle it (PME, AP1600, I don't know what else, Planewave Ascension, ASA DDMM ) and you're up over $50K for a GSO setup. Trash the focuser and throw in a FLI Atlas or at least a feathertouch and you're up another 4Gs.

Still it would be 20 inch. If you could overcome the inevitable half dones on the system then it could be good. The good thing about the GSO's as Paul has shown the optics seem fine.

Haven't seen any other GSO RC 12's or above images other than Pauls though.

Greg.

Last edited by gregbradley; 05-08-2015 at 02:14 PM.
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  #8  
Old 05-08-2015, 02:02 PM
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Quote:
Originally Posted by glend View Post
I really hope they are going to address some of the lingering quality issues of their smaller RCs. The need to have a focuser collimation ring, and they don't ship with one. Scope delivered badly out of collimation , just no point claiming they setup in the factory if few seem to get one that doesn't take time to get sorted. Etc etc.

Actually the collimation ring has been addressed some time ago. All scopes 12" and up have a rear collimation ring as part of the scope now. I had a bit to do with that development as the rig I am using is so heavy the old mirror assembly was not up to holding that sort of weight. Part of the solution was to develop a centring ring for the rear assembly.

I agree about the collimation being out but if you own a folding scope of any type you should know how to collimate it front and rear. I have never known a either a Newtonian, SCT or RC to never fall out of collimation when being moved by road transport. So being shipped overseas might just prove to disturb the collimation.

A long focal length will need a wide sensor I suspect if you are going to use it at native. As an example Martin Pugh is using a STXL11002 on his CDK17 and that does not produce really wide looking images. There is a nice even fit with that combination.

The 20" will need a big mount to carry it. An EQ8 could theoretically work but whether it will guide correctly or not is another matter.

Even if there is some teething problems with these big scopes they will still be a 1/4 of the price of their more prestigious cousins, so worth considering if you are on a limited budget.

I had considered the 16" but at present I am trying to eliminate other equipment problems. Cash is a little short too, so that kind of kills the idea for now.
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  #9  
Old 05-08-2015, 03:40 PM
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Originally Posted by gregbradley View Post
14,000 Euros would make it about AUD$27,000 landed. Hardly bang for your buck.
Hmm those prices across their entire range a huge. They are saying 3499 euro for the 12". Australian price is that in dollars. Euro is about double AUD so those prices are ridiculous.
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Old 05-08-2015, 04:00 PM
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rustigsmed (Russell)
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Originally Posted by Paul Haese View Post
Hmm those prices across their entire range a huge. They are saying 3499 euro for the 12". Australian price is that in dollars. Euro is about double AUD so those prices are ridiculous.
yep, actually if you log in with an Australian address it drops to 11,756 eu ... perhaps more comparable to what it will be in oz .

but then again compare the 12"

TS 12" = 2,940eu
Andrews 12" = $3799
ratio of 1.292

TS 16" = 5,461eu
Andrews 16" = $6999
ratio of 1.282

TS 20" 11,756 eu
Andrews 20" ?? maybe with a ratio of 1.287 = $15,129

a much better result if the ratios hold true.

Russ
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Old 05-08-2015, 04:02 PM
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If it were AUD$13990 here that makes more sense and a lot more tempting.

Greg.
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Old 05-08-2015, 04:24 PM
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I need to make a correction about Euro. $1.48 to the Euro. Yep at 15K it would be a good deal for such a large aperture but it would still need a focusor, a shroud, a dew heater, adapters etc.
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  #13  
Old 05-08-2015, 04:41 PM
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A 20" RC at 16k is awesome, but still out of reach for me.

do you think my Pentax MS-5 could handle this, it had a C14 and 5" Pentax Refractor on it. Information i could find says it can handle 50kg but i think that is very conservative.
Pic from net of the mount carrying a Mewlon 300.
http://www.takayuki-astro.com/image/equip/m300.jpg
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  #14  
Old 05-08-2015, 06:03 PM
clive milne
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Quote:
Originally Posted by Paul Haese View Post
I need to make a correction about Euro. $1.48 to the Euro. Yep at 15K it would be a good deal for such a large aperture but it would still need a focusor, a shroud, a dew heater, adapters etc.
Could always mount the secondary on a PDF located on the spider...
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Old 06-08-2015, 06:41 PM
glend (Glen)
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Teleskop-express prices include VAT at 19% which is applicable inside the Euro zone but not on sales outside. So multiply their price by 0.81 and you should get the Euro amount to convert to AUD. That's how it has worked on car parts I have purchased from Europe. However it is up to the retailer to process the export exemption with their VAT payment process.
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  #16  
Old 06-08-2015, 07:20 PM
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OK it's a 20"...but...does it have the following?
  • A 50kg instrument payload
  • 100mm diameter instrument adapters
  • 90mm diameter fully corrected reducers and field correctors
  • Zero image shift, servo controlled secondary focuser
  • Integrated touch-screen focus, environment and instrument rotator control
  • Zerodur optics with a 98% strehl and 96% reflectivity.
  • Finite point analysis and machining to reduce dead weight by 80% or better
  • Remote mirror shutters.

Large and elegantly engineered imaging telescopes up until now have not been cheap...hence, to use an automotive analogy, I'd very much like to see whether a Great Wall ute would seriously challenge the latest S-Class.

My money is still on the Benz.
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Old 06-08-2015, 09:18 PM
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sn1987a (Barry)
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There's only one way to find out - we all stump up a thousand $ each and ....
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  #18  
Old 06-08-2015, 10:29 PM
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Somnium (Aidan)
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Quote:
Originally Posted by Peter Ward View Post
OK it's a 20"...but...does it have the following?
  • A 50kg instrument payload

.
50 kgs ... that is some camera . GSO give you the body and the engine and a wad of cash to pay for whatever trim you like.
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Old 07-08-2015, 10:25 AM
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Chris85 (Chris)
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Just thought I'd share my friend in Perth who's using the GSO 14" http://www.astrobin.com/users/ntk.thava/
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  #20  
Old 07-08-2015, 10:37 AM
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50 kgs ... that is some camera . GSO give you the body and the engine and a wad of cash to pay for whatever trim you like.
With a 50kg instrument rating there will be bugger-all flexure with say a 5kg CCD+CFW at the focal plane.

It will be interesting to see whether GSO deliver 5 micron spot sized across a 65mm field....which, to excuse the pun, is even more to the point
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