Any feedback on GSO 10"RC [Archive]

gregbradley

14-01-2010, 05:35 AM

Its possible that flocking the secondary dewshield area may reduce those reflections. I have heard of that handling persistent reflection problems in an RC type scope before. Something is probably unpainted or shiny in the optical train. Perhaps also the baffle tube could be flocked but I'd start with the secondary shield. Then if no joy I'd look through the optical train for any other bright metal areas.

The suggestion it has something to do with pixels in that report is very humorous. I have never seen that before and used lots of CCD cameras.

It is true some filters reflect worse than others. Baaders and Astronomiks and FLI research grade filters are known for good performance in this area.

Greg

Moon

15-01-2010, 01:41 PM

Interesting. Peter - do you care to stop us speculating?

On CN (http://www.cloudynights.com/ubbthreads/showflat.php/Cat/0/Number/3557169/page/0/view/collapsed/sb/5/o/all/fpart/1) they are talking about a 16 inch truss verison by the end of the year for $7995.

Moon

15-01-2010, 01:56 PM

Then how to explain the grid shape of the reflections? (especially the 5th image) To me it looks like the type of reflections you might expect off a surface that was covered in micro lenses acting as prisms (the sensor) then reflecting back off the filter or some other glass in the optical path.
I have never seen it before either - that's why it's so interesting :P

telecasterguru

15-01-2010, 02:30 PM

I am amazed at the amount of work required to make the scope road worthy. Hopefully a lot of these issues will be fixed when the carbon fibre tube OTAs arrive.

I might wait for the 16" and by the time it is ready I may have enough for a deposit.

Frank

AlexN

15-01-2010, 03:10 PM

The focuser is the biggest problem with them from what I understand... The reflections shown in the images on CN happen in newts and SCT's too.. its generally a reflection of the primary in the secondary.. I've seen it with plenty of different optical systems.

The sagging focuser is an issue, but its easily sorted out... a 3" Feathertouch will hole absolutely any load you throw at it, and considering the price of the scope in comparison to other 10" RC scopes, you're looking at $4600 with a 3" FT... If you flocked the 2ndry and whacked on a good focuser you could be looking at a very nice scope...

Take Paul Haese's 8" GSO RC... His had reflection issues and focuser issues when he got it... it's now producing epic images with the scope just from a new focuser and flocking.. The revised 8" had a baffle that does not need baffling, however the focuser on the revised scope is still not capable of holding a serious camera setup.. for a DSLR it might be fine, but for a mono CCD, filter wheel and an OAG the focuser is horribly inadequate.. Having said that, most consumer scopes have average focusers that are not capable of holding a big imaging setup, the fact is that on a short focal length scope the affects are nowhere near as noticeable as they are with these longer focal length scopes.

telecasterguru

15-01-2010, 09:40 PM

Alex,

I was unaware that feathertouch made a focuser for this scope although I thought that it would happen in time.

I have looked on their site and could not see what I thought was an appropriate focuser.

I was of the opinion that back focus would be a problem and this has also made me hesitant.

Also using a 5DII with small pixels on such a long focul length may be less than ideal.

I really want one of these scopes and if feathertouch can supply the goods then the deal will surely be done. I have heard some very good things about the optics of these OTAs.

I think that if I get one of these RCs with my ED127 then I will have all the bases covered. (until something else comes along)

Frank

AlexN

16-01-2010, 12:56 AM

You wouldnt have super-wide field covered mate... :) I have my 480mm focal length APO, will be getting the ED127 and then will look into getting another 8" RC or a 10" maybe...

The 3" feather touch focuser can easily be used on the 10" RC, all you need to do is find out what the rear thread is on the RC, then contact starlight instruments and request an adapter be made from that thread to the 3" FT... They already make the adapter for a 2" Feathertouch to the 8", although a 2" focuser will vignette the 5D sensor.. So it would be better to go to a 3"..

As for the small pixels with a long focal length - don't worry about it.. Oversampling is great... just make sure your guiding is tight!! :D

Tandum

16-01-2010, 01:21 AM

I'd prefer a Vixen VMC260L (http://www.optcorp.com/product.aspx?pid=1-599-1088-10685). Native FL of 2990mm at F11 or 1850mm with F7 reducer and a 60mm hole in the arse end. 10Kgs.

AlexN

16-01-2010, 01:39 AM

Very true Robin, the VMC260L @ F/7 would be an amazing imaging scope.. very large corrected image field, light weight and optics are reportedly every bit as nice as the VC200L...

The downside to the VMC260L is its price.. Although I've not checked it recently, I considered one when I bought my C11 and scarily enough, the C11 was much cheaper...

Tandum

16-01-2010, 04:35 AM

I see the C11 at almost $6K here. The Vixen is around the same price as this chinese RC and it has a reducer made for it.

el_draco

17-01-2010, 04:03 PM

You would think these manufacturers would start to get their equipment tested BEFORE they massed produced it. Gawd, you spend an arm and a leg, then toss in the other two just to fix the B.S. that ought to have been fixed with a little design testing. Getting tired of it?

Octane

17-01-2010, 04:20 PM

I may have asked before, but, can someone explain to me what realistically the advantage is of one of these over a similar aperture Newtonian with a coma corrector?

The Newtonian would be faster, between 2 and 3 stops, and, a third to a quarter of the price.

Or, am I missing the point altogether?

H

AlexN

17-01-2010, 05:00 PM

Focal length H.. Not only focal lenght, but size of the telescope too..

A 10" F8 newtonian would require a serious mount to stop any vibrations, would likely weigh a fair bit I'd say it wouldn't fit in most of our cars. Yes, the average 10" newt is F/4.7, so its faster, but the people buying these RC's aren't concerned about fast, they really want the longer focal length of these scopes...

Octane

17-01-2010, 05:32 PM

Oh, OK. Gotcha.

In that case, what advantage do they have over a traditional Schmidt-Cassegrain?

H

AlexN

17-01-2010, 05:47 PM

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.

Octane

17-01-2010, 05:50 PM

Makes sense, cheers.

I still have my heart set on an imaging Newtonian such as the Astrotech ones, or, a C9.25 (carbon fibre, if possible).

H

AlexN

17-01-2010, 06:09 PM

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...

Peter Ward

18-01-2010, 06:47 PM

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.

Bassnut

18-01-2010, 08:16 PM

He he, I love it, start a price war and dump it, soooo cool :thumbsup:.

Paul Haese

18-01-2010, 10:43 PM

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.

mick pinner

18-01-2010, 11:04 PM

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.

AlexN

18-01-2010, 11:13 PM

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?

Paul Haese

18-01-2010, 11:17 PM

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.

mick pinner

18-01-2010, 11:42 PM

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.

Prickly

20-01-2010, 08:56 AM

Humayun,

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.

Cheers
David

Satchmo

20-01-2010, 09:05 AM

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.

Manav

20-01-2010, 10:30 AM

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 (http://www.optcorp.com/product.aspx?pid=1-600-1569-13924).

Paul Haese

20-01-2010, 12:30 PM

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.

Satchmo

20-01-2010, 12:45 PM

Could you elaborate on this statement , Paul. How so 'not as sharp' , on axis or off axis or both ?

Paul Haese

20-01-2010, 12:55 PM

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.

TrevorW

20-01-2010, 01:02 PM

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.

Satchmo

20-01-2010, 01:52 PM

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.

Mark

Moon

20-01-2010, 01:59 PM

Mark
Very interesting. Can you do a similar test, comparing the off axis performance of an 8"RC and a 16" RC?
James

multiweb

20-01-2010, 02:00 PM

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?

Paul Haese

20-01-2010, 02:22 PM

Like I said I have not seen any really. Maybe just the odd one.

So you don't consider the images I did long before Peter as remotely decent? You must have seen these below. Or do you only look at images produced in NSW?:)

Take a look at these

http://paulhaese.net/EtaCarinacloseup.html

http://paulhaese.net/NGC5128closeup.html

http://paulhaese.net/trifidcloseup.html

http://paulhaese.net/m16closeup.html

All posted right here on IIS and not exactly what I would call shabby either. You must have much higher standards than I do. (which I seriously doubt):P

Satchmo

20-01-2010, 02:38 PM

Yes, the performance with a quality Barlow design will be very similar to native F ratio. Powermate design aren't technically a barlow lens although they do double the magnification .

There are high end Barlows designed for very fast scopes with no vignetting such as this :

http://www.asa.ikreator.hu/ikreator/asa/cms_pub/content_97-en.html

( Need a 3" JMI focusser though )

The Astrosystems astrograpghs are offered with this option ( have your cake and eat it too ...)

Satchmo

20-01-2010, 02:46 PM

At the time Peter posted his Omega Cen pic If I remember from a _very long_ thread , all the 'tyre kickers' had fallen asleep waiting for you guys to sort out your drooping focussers , and the pictures I saw up until then were very average:) I certainly don't recall seeing anything decent up until that time .

Nice pics. Congratulations . There is nothing at least in theory that suggests that Newts can't work just as well with an amplifier lens . I suspect its due to the implemetation more than anything else. A cheap Barlow lens is not going to do the job.

Mark

Manav

20-01-2010, 03:25 PM

On a side note - Awesome pics Paul!

Photon Addict

20-01-2010, 03:34 PM

If you are considering purchasing a GSO RC and have reservations regarding the quality of the focuser, bear the following in mind:

Your imaging requirements can be SIGNIFICANTLY different to the next persons. Do you intend to only connect a DSLR and use a separate guidescope, or are you putting on an imaging train consisting of an adaptive optics off-axis guider, large capacity filter-wheel and a heavy large-format camera (800g vs 5kg or greater). The market for these scopes is comprised of people just starting out with DSLR's (or even guide-cameras) to pretty sophisticated setups.

If all I was going to use was a 800g DSLR (Canon 450D), I would be turned off the purchase if I had to pay for the top-end quality focuser that would be required for the heavy imaging trains some guys use. Where do you draw the line? Focuser good enough for 1kg, 2kg, 3kg, 4kg, 5kg.... It makes perfect sense for the manufacturer to cater for the lowest common denominator, then give the user the choice of their own focuser that is ideally suited to their own needs. So the real question is: is the stock focuser good enough for a DSLR with nothing else?

I would be quite happy if they sold the scope without a focuser - but what do you do when it is delivered and the preferred focuser is still being shipped? No playing then with the new toy....

TrevorW

20-01-2010, 05:22 PM

You target the market supply cheaper focuser sell more scopes then leave it up too the end user to choose their own knowing that in reality this is what happens anyway.

One should remember these are mass produced consumer items. one size fits all

Some might like Feathertouch, others have a preference for Moonlite, JMI or Robofocus and even Toadloaders

I've seen really good images from inexpensive set ups and vice versa.

I think we make too much out of what is better APO vs RC v Newtonian vs Mak

At the end of the day it doesn't really matter what you've got it's how you use it.

In fact I can see myself in years too come with possibly one of each.

JethroB76

20-01-2010, 05:58 PM

Why dont they offer these scopes without a focuser, or offer an upgrade option at purchase?

leinad

20-01-2010, 06:24 PM

To start off topic:
When those new 8"RC owners contacted the seller about the initial issues; did you guys ever get a reply or resolve?
Sounds to me like GSO have serious QA problems if these scopes are being sold with design flaws, collimation out of whack, optics problems.
I'd be sending strong questions to the manufacturer and wanting a warranty replacement or money back.

People are complaining about collimation out of the box; and focuser issues? Isn't this the norm with any Cass, CDK, RC type scope? Be prepared to collimate and adjust the optics yourself unless you send it back to be 'serviced'.

This is a poor-mans RC no? GSO focusers aren't exactly superior..
Seems like everyone is expecting this scope to be similar to a scope over $5000 for some reason.

Same could be said for the CDK type design of the VC200L. An excellent performer; but lacking with spider vane design and poor focuser system.
Both can be upgraded to improve the scope dramatically.

:shrug:

Paul Haese

20-01-2010, 08:25 PM

leinad, I was pretty much in contact with Jim Sheng within hours of sending him my initial impressions. He was quick to respond. When I did my review of the scope and posted it on the internet items were fixed on the following batches. The unfortunate part is that the new baffle will not fit the older scopes so I had to make do with what I had and worked on flocking the baffle myself.

I think that the scope really needs to be another 4 or 5 inches longer to prevent dewing problems.

Bassnut

20-01-2010, 08:57 PM

Exactly, sheesh, so much grief. A carbon fiber RC for some $1800, thats insane :P. You pay for what you get, in this case not a lot (the price), so what you need to replace the focuser and deal with some short falls, get over it, you lot are not are not so nieve to think you get the *lot* for that price?, despite the advertising. If you want the lot, pay too much for an RCOS (the TCC alone is a whole different world) and be done with it.

Seems to me, GSO RCs are are very good deal indeed, so long as you accept some fiddling maybe required. Im amused by ppl who think the world owes them the ultimate quality product regardless of price, and ignore simple common sense.

telecasterguru

20-01-2010, 09:36 PM

Thanks for all the information everyone. From my original question I was hoping to find out if anyone that had actually purchased one of these scopes and if they could give me a lead on how they operated. I have read and heard a lot about the 8" GSO RCs.

From what I can gather the 10" GSO RCs have very good optics, not very good focuser and don't weigh an enormous amount. Although I have not been able to find out how much they weigh. Somewhere between 12 and 15kilos I believe? I don't have any idea whether they are easily balanced or how much back play is required to gain focus when imaging. I am assuming that it would be quite a bit. Maybe up to 300mm.

I was expecting to buy a new focuser anyway. I bought a Moonlight for my ED127.

If the optics are good then the main battle is won.

Please let me know if any of this is wrong.

Frank

TrevorW

20-01-2010, 09:44 PM

Frank if the 8" optics are a thing too go by then the optics will be good IMO

Mighty_oz

20-01-2010, 09:53 PM

Interesting discussion :)
As a beginner imager i looked at these scopes two, but waited to see what they would be like.
They can certainly take wonderful images, but that is to be expected as they are a scope designed mainly for imaging not visual.
What I don't like is that it took a person to buy one before obvious design defects were addressed.
So did they actually do "serious Q&A" or we tested it some that will do ?
Baffles that don't work properly and a focuser that droops on light imaging gear ?
Enough said on their quality testing, they have brought RC's to the average imager if u want one which i'm glad of as i will probably get one two, but i'm waiting to see what faults the 10"will bring before i consider spending my hard earned cash.
Also a G11 should handle this scope ok for imaging yes ? ( just a short side track )
Oh to win lotto :)

telecasterguru

21-01-2010, 07:01 AM

Mighty Oz,

I hope the G11 will handle one of these scopes as I have just bought a G11 for just that job.

Frank

bratislav

21-01-2010, 10:34 AM

Well, here's the 100% crop of the area in Eta Carinae done with a Newtonian (not very good example but that is the only image that I can directly compare now with those you offered).
To my (old!) eyes, detail in it is even sharper than on one you offer on your site. Note some tiny Bok globule, those black 'dots', completely absent in your image - can you give us 100% crop as well ?

I have clocked some globulars with 2.2 arc second FWHM, that is my best to date (and that is always going to be SEEING limited, with better seeing I could certainly do even better). What FWHM (long term) do you get with your RC ?

Bratislav

bratislav

21-01-2010, 10:59 AM

Happy to volunteer this pic of the same (heavily jpeg compressed to scrape under attachment rules) done with a humble Newtonian ...

Mighty_oz

21-01-2010, 11:09 AM

Looking forward to your input as to how well it does :) And the pics 2 !

Paul Haese

21-01-2010, 11:12 AM

Bratislav, here is a crop of my image on my site and I think mine is sharper, might be time for a new prescription :P. There arn't any bok globules where you are looking. I think you are looking at dust on the sensor.

BTW I agree with Bassnut all the way. Well put Fred :thumbsup:

multiweb

21-01-2010, 11:33 AM

I think you're right. It might be dust. Here's a HST crop of the area.
Although your picture in this case is much sharper than a newt I agree that a well collimated newt can be on par with those GSO RCs.

bratislav

21-01-2010, 01:06 PM

I stand by my comment, it was not a very good example :lol:
But armwaving notwithstanding, FWHM is easily obtained single number that can be compared without any squinting at the screen. As I said, I now routinely get into 2.5 arcseconds with occassional excursion towards 2" flat. I don't think any RC would do any better with same seeing conditions. I'll post some 100% crops of those sessions later.

And BTW if you think GSO RCs are such a good value at 2.5K (or whatever you ended up paying after all of the mods), consider that my Newtonian has whopping 200$ invested into it ! :P

bratislav

21-01-2010, 09:10 PM

Here's the (again heavily reduced and compressed jpeg) of NGC104 done with a Newtonian. Measured FWHM on raw subs was around 2.2 arcseconds for that shot (combined exposure around 40 minutes). Second image is 100% crop.

Let' see that sharper image from RC boys ...

DavidU

21-01-2010, 09:20 PM

That's pretty sharp !

el_draco

21-01-2010, 09:38 PM

This is a very pertinent comment. The demands on equipment vary dramatically and I would think the obvious solution is to ship the unit without a focuser altogether. The comments I see indicate that the focusers being shipped are sub-standard and will only end up rotting some place. Thats a waste of money and materials.

Having said that, you would think that someone buying an decent R.C. had imaging in mind and the manufacturers would be wise to build a back plate capable of supporting whatever imaging flatform may be required, with a standard rear cell thread yes? Likewise, anyone spending bucks on a decent OTA is likely to have a specific imaging goal, and hence focuser in mind... :question:

telecasterguru

21-01-2010, 09:41 PM

Bratislav,

What camera are you imaging with to get these images?

Frank

AlexN

21-01-2010, 09:59 PM

Not to sound like a downer on good times here, but how did we get onto Newtonians Vs RC's in the quest to answer the question "Any feedback on the GSO 10" RC?"

Each to their own boys... There are things you can do with a newt that you wouldnt bother doing with a newt, there are things you can do with a newt that you couldnt do with an RC too... Simple answer, buy both...

Showing images of Target X from one scope, with a specific camera, taken in certain conditions and comparing them to images from a different scope and camera setup in different operating conditions of a different target is a really really big waste of time..

DavidU

21-01-2010, 10:18 PM

So......... no one has a GSO 10"RC then?

Satchmo

21-01-2010, 10:59 PM

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 .

rat156

21-01-2010, 11:31 PM

On the focuser subject, I have an 8"RC with the newer focuser as delivered. This is an upgrade to the one Paul has. I have still changed mine over to a Moonlite, but mainly because I hang a lot of weight off it. I believe that for most people, without the massive rig I've got, the standard GSO focuser would be easily good enough to do the job.

So unless you've got the several kgs of stuff hanging out the back of your RC, I wouldn't bother with the focuser upgrade. The 10" focuser looks even better than the one I have.

Here's a pic of mine waiting for the clouds to go away!

Cheers
Stuart

rat156

21-01-2010, 11:57 PM

Here's a shot I did of 47Tuc, FWHM of about 2.5", this was with the original focuser and the scope as it was delivered. It needed a bit of a tweak of the collimation.

Cheers
Stuart

bratislav

22-01-2010, 09:48 AM

<Off topic>
The camera used was QHY8, at approx 1.1 arc sec per pixel scale.
And sorry Alex, comparing best FWHM is not waste of time, but the only way to objectively compare (debunk?) the resolution abilities of certain configurations.
Stuart, was 47 Tuc shot with AO unit ?
</Off topic>

AlexN

22-01-2010, 01:36 PM

Comparing FWHM isn't all that useful, your local seeing conditions impact on FWHM. More often than not, your seeing conditions will be a lot worse than the resolution provided by your telescope... Also longer focal length scopes will almost always give higher FWHM's than a short F/L system given identical seeing conditions... Just an observation I've made when testing two different optical systems side by side..

Don't take it the wrong way mate.. I'm more a newtonian fan than an RC fan... And agree with much of what you and Mark have said, Its just your method of proving your point seems flawed to me.

Fact of the matter is you're comparing two very different optical systems, in different seeing, with different mounts, different cameras... Trying to get an idea of which scope produces better star images. There is no standardization in your comparisons, so they aren't definitive proof of either systems superiority..

Both optical systems are producing great images for their owners... That should be good enough for everyone..

rat156

22-01-2010, 04:11 PM

Yes it certainly was using the AOL. This reduces the amount of mount induced star bloating to almost zero, when it's properly used. Unfortunately the AOL doesn't react fast enough to counteract seeing induced star bloating.

Now the only way to positivley resolve (pun intended) this is to have a shootout. We need Bratislav, myself and someone with a big refractor, all around the same FL on one night and a bright target with a good guidestar, then swap my camera setup between the lot and see which scope is best. I also have a Meade 10"ACF OTA, which we can add into the shootout. We really would need a CDK as well, then we could call it a shootout at the DK corall.

Maybe we could use the LMDSS on a full moon, when it won't be being used...

Back on topic, I know someone with the 10" RC, we will be comparing notes soon, when we get together for a BBQ.

Cheers
Stuart

rat156

22-01-2010, 04:14 PM

Hey Bratislav,

Can you send me a sub from your 47Tuc, I'll align it with the best of mine then we can really compare. Seeing is believing as they say.

PM for contact details if you've lost them.

Cheers
Stuart

Moon

22-01-2010, 04:32 PM

I for one would love to see a fair dinkum shootout.
Not sure where we can find a CDK though but I agree it needs to be in the mix.

leinad

22-01-2010, 04:39 PM

VC200L is close enough to poor-mans CDK.

TrevorW

22-01-2010, 04:51 PM

Ok shoot me I couldn't hold back any longer

I've gotta a bigger one that you

NAH !! NAh !! Nah!! :P:P

WRGAF ;)

Moon

22-01-2010, 04:51 PM

Well I guess that can be the backup plan in case we can't find one, but don't forget these (http://www.planewave.com/index.php?page=3) claims.

leinad

22-01-2010, 08:01 PM

Well I'm afraid closet you may get is 12.5".
What's the point in pointing at Planewave? We might as well be talking about RC Optical Systems as well.
http://www.rcopticalsystems.com/

AlexN

22-01-2010, 08:43 PM

Why not.... This thread has gone every which way anyway.. Lets get a 12" F/9 LZOS triplet APO, a 12.5" RCOS, a 12" Astrophysics Mak-Cass, a 12.5" CDK and an ASA N12 Newt and see how they fare against the GSO 10" RC, VC200L, Skywatcher ED80 and GSO 8" newtonian, and SW 180 MC...

Should be a fun test.. Fair too... Oh hey, lets put them all on different mounts with different cameras under different quality skies too.. That way it should be a much better test to see which telescope is the best.

Any other optical designs we need to include?

Bassnut

22-01-2010, 09:40 PM

Mike Berthon-Jones (ASNSW) here in sydney has a 12" Planewave CDK

Paul Haese

23-01-2010, 11:37 AM

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.

Luke Bellani

23-01-2010, 02:30 PM

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.

AlexN

23-01-2010, 02:33 PM

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 Bellani

23-01-2010, 02:46 PM

Hi Alex,
Yes I know, but I just couldn't resist for the photo :lol:

I'm about to start work on my obs and then hopefully will be able to get down to some serious stuff.

Cheers,
Luke

binofied

23-01-2010, 03:10 PM

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.

Luke Bellani

23-01-2010, 03:41 PM

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

AlexN

23-01-2010, 03:52 PM

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...

Luke Bellani

23-01-2010, 03:59 PM

Hmmmm! Yes I wouldn't be surprised if a 5kg camera taxed it a bit.;)

Cheers,
Luke

telecasterguru

23-01-2010, 05:19 PM

Well everyone,

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.

The 350D goes on first and see what we can find.

Frank

Mighty_oz

23-01-2010, 05:24 PM

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.

telecasterguru

23-01-2010, 05:41 PM

Luke,

Love the picture of your rig.

What was the process for collimation that you used?

Any ideas for collimation will be gladly accepted. I have a laser collimator.

Frank

AlexN

23-01-2010, 05:52 PM

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....

Best of luck! :)

DavidU

23-01-2010, 06:07 PM

:thumbsup::thumbsup::thumbsup::thum bsup:AWESOME Frank......pic's !!!!

telecasterguru

23-01-2010, 06:49 PM

Alex,

I have never owned an SCT let alone collimated one.

I have collimated newts but I assume that they have nothing in common with SCTs regarding collimation.

Dave, it's Saturday and the clouds are here for the weekend. Again.

I've gotta get a job where I work on Saturday and Sunday and have the rest of the week off.

Frank

AlexN

23-01-2010, 11:00 PM

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..

marki

24-01-2010, 12:17 AM

Long exposure imaging with a newtonian :rofl::rofl::rofl::rofl: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 :rofl::rofl::rofl::rofl: strap it down to stop the shaking coz the wind has exceeded 1 knot :lol:. Put it back in its dobsonian mount where it belongs.

Mark

Satchmo

24-01-2010, 09:31 AM

An 8" F5 Newt tube is about 12" longer than the total length of an 8" RC with CCD camera set up behind .

marki

24-01-2010, 01:00 PM

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.

Mark

mick pinner

24-01-2010, 01:12 PM

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.

gbeal

24-01-2010, 01:19 PM

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

marki

24-01-2010, 01:38 PM

Well boys thats exactly what I am doing, having a little fun. Everytime a thread comes up about the GSO RC's three things always occur.

1. The focuser: just change the bloody thing and be done with it.
2. reflections: Show me a system totally free of reflections on any object and I will bite myself on the bum. This has been largely fixed (not totally as it is not possible) in the new GSO tube.
3. What about newts? What about the price to properly mount a newt to get good images let alone fitting the thing in a car.

Seems to me people are all too keen to trash these scopes (and it's a good one) with no real reason. I could just as easily say AP scopes are crap because they don't come in dayglow orange and golly I would have to paint it myself :P.

And Mick I am not saying it can't be done just that it is not really practical when there are other easier options available.

Mark

telecasterguru

24-01-2010, 03:03 PM

Thank everyone for the feedback and as I have now purchased the GSO 10" RC I think this thread is now redundant.

Frank

TrevorW

24-01-2010, 04:01 PM

Good onya Frank and enjoy :thumbsup:

Paul Haese

24-01-2010, 04:21 PM

Frank,

congratulations on your purchase of this fine scope. Please let me know if you have any questions relating when you start imaging with the scope.

telecasterguru

24-01-2010, 04:41 PM

Trevor, thanks for the kind words.

Paul,

Thanks for the offer of help and I will certainly take it up as needed,

Collimation will be the first issue and I will need a clear night for that to happen. It actually looks pretty easy from what I have read on the web. (famous last words).

Frank

Bassnut

24-01-2010, 05:14 PM

With you there totally Mark :thumbsup:(dont know why you cranky about it though ;)). A big long newt on a dodgy mount (of the same same apature) looses any price advantage it has over the RC , "guiding is paramount" (sorry, I didnt mean an obscure reference:P). Small newt, fine, but a 10" newt?, nah, a 10" GSO RC with a better focuser and some fiddling, even at a higher price would beat it hands down *for long exposure imaging* just on guiding alone (from what pics I see and hear).

The trashing of GSO RCs comes from expectations of the magical "RC" tag and comparisons with other RCs, which are all vastly more expensive, and ignoring the stupid price. OK the problems are unfortunate, but relatively irrelavent given the result possible.

marki

24-01-2010, 06:23 PM

I bet you do Fred ;):P and I don't even own one of these scopes!

Congrat's Frank I am sure you will love the scope to death. They are not difficult to collimate and have nice sharp views and are very well finished if TrevorW's scope is anything to go by. With a good moonlite or feather touch attached you can't go wrong.

Mark

AlexN

24-01-2010, 06:39 PM

I just read on Cloudy Nights forums that Astrotech are releasing a 10" version with Carbon Fiber tube and a 3" Feathertouch at NEAF this year... It will be available through Astronomics and Optcorp.

If that doesnt silence the nay sayers I dont know what will..

Ps. Estimated price tag (From the owner of Astro-Tech) is $3900USD with CF tube and 3" FT.

What was that saying again? You get what you pay for??

rat156

24-01-2010, 10:59 PM

Hi All,

As there seemed to be some interest in the Newt vs RC comparison, I got a sub from Bratislav and one of mine taken a few days apart. I started a new thread. Remember this is for those of us that are genuinely interested in these things, NOT a pissing contest.

http://tinyurl.com/y8877t2

Cheers
Stuart

Luke Bellani

26-01-2010, 03:26 PM

Hi Frank Sorry for the delay in replying.

I did a Google search and found this document on the Astronomics web site regarding the AstroTech 8"RC and figured it also applied to the 10" RC.

I just used it as a guide and it ended up being a fairly simple process.
Here is the link.
http://www.astronomics.com/main/documents/astro%20tech/astro-tech%20r-c%20collimation.pdf

Also congratulations on your fine purchase. :thumbsup: :welcome: to the club.

Cheers,
Luke