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GSO vs TSO... for Ritchey Chretien telescopes

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#1 PFitzhorn

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Posted 18 October 2017 - 06:18 PM

Now that I've retired and convinced the wife that I can spend a pot of $$, I've been planning an upgrade in astrophotography from the old Celestron Powerstar C8 to a Ritchey Chretien 10" or 12".  However, I'm now totally confused.  I have found what appears to be exactly the same RC telescope branded GSO (Guan Sheng Optical - who I think actually makes them), or branded TSO (also called TS Optical), or the name of the retailer selling it.  They all appear to have the same diameter, F/ratio, 3 cooling fans, focuser (although there are a few differences), mirror coatings, Losmandy mounts, one of the three designs - carbon Serrurier truss structure - metal tube - carbon tube, among other similarities.  The prices are surprisingly similar as well.  Reviews of them look stellar (ha ha) given the price.  However, it looks to me like I choose (1) the design and (2) the retailer, not specifically whose name is on the RC telescope.  Is that right?

 

Seems like no matter which one except for maybe the metal tube variants, these RC's have been receiving great reviews.  Please advise the RC novice here.

 

 

 

 



#2 Kokatha man

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Posted 18 October 2017 - 06:56 PM

"TS Optics" are the "Telescope Express" branded GSO R-C scopes, a large & reputable German Astro-dealer...this isn't an uncommon re-branding of GSO equipment who are a Taiwanese firm who have built a good reputation over the last couple of decades with their products. waytogo.gif

 

TS/TE have the GS of GSO (Guan Sheng Optics) as a prefix to the models they sell & advertise some upgrades to the basic GSO units...they may also individually test the scopes they purchase from GSO or offer some other benefits...eg, expediting product issue resolutions, although this is not to say that is a problem...

 

You have to decide where any cost etc benefits reside, naturally! wink.gif



#3 Alex McConahay

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Posted 18 October 2017 - 08:46 PM

Add TPO for the OPT version of GSO.

Does anybody know how to spell whole whole words anymore?

Alex
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#4 Kokatha man

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Posted 18 October 2017 - 09:20 PM

Add TPO for the OPT version of GSO.

Does anybody know how to spell whole whole words anymore?

Alex

lol.gif Well, I did give the full names for those acronyms/abbreviations Alex...but maybe I should've added that the TS was the Teleskop Services aspect of Teleskop-Express - I'll let you decipher OPT..! rofl2.gif



#5 Alex McConahay

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Posted 18 October 2017 - 09:34 PM

OPT is Oceanside Photo and Telescopes. They are a telescope store not too far from my house.

Alex

#6 PFitzhorn

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Posted 18 October 2017 - 11:43 PM

Thanks for the answers - and abbreviations. 



#7 Ken Sturrock

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Posted 19 October 2017 - 01:29 AM

Moving from the Beginners' Forum to Beginning & Intermediate Imaging.



#8 glend

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Posted 19 October 2017 - 02:07 AM

In my experience with owning a GSO RC08, i would not suggest this as a scope for a novice, or just about anyone else. They are difficult to collimate correctly, and very easy to mess up if you don't understand how RCs work, or if you move the primary. They are certainly not like Newts and people get into big messes thinking they will move the primary to collimate like you do in a newt. These scopes are cheap for RCs and attract folks on a budget, but usually you have to spend at least the scope cost again on tools to assist collimation, and focuser collimation rings or replacements.

I would start with something easier. If you have a Celestron background, something like an Edge HD8 gives you advantages over the RC08. Sure it cost more but it is also flat field, long focal length, it is easy to collimate without tools, it stays collimated, with the reducer you can image at f7. The Edge will have excellent resale value, whereas used RC08s are hard to give away because so many people get sick of them.

I would hate to see you have a bad experience.


Edited by glend, 19 October 2017 - 02:09 AM.

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#9 ImNewHere

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Posted 19 October 2017 - 08:46 AM

If you can afford the 12 that's what I'd get, as long as you have the mount for it that is. After some initial stumbles I love my 8.



#10 Ken Sturrock

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Posted 19 October 2017 - 11:34 AM

You may also want to check out this related recent thread over in Cats & Casses.



#11 Jared

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Posted 19 October 2017 - 12:22 PM

I agree that a 10" or 12" RC is not exactly a beginner's scope for learning imaging, but that doesn't mean you can't be successful, and the scopes can be very rewarding longer term.  Here are the problems for a beginning imager (which I assume you are, but please correct me if that's not so):

 

- Imaging at 2,000mm to 2,500mm is really hard.  Your tracking must be perfect to get round stars.  Your seeing needs to be good for the image to not look soft.  You better be using a high quality mount if you are working at 2,000mm focal lengths and above (or at least one you have fully optimized).  This is nothing specific to Ritcheys--it would apply to any scope at these focal lengths.

- They are, indeed, more challenging to collimate than most scopes since you have two aspheric mirrors.  That means you need only need to get the tip/tilt correct for the mirrors, they need to have their optical centers on the same axis.  With an SCT or a CDK, for example, if the secondary is not exactly on axis it just changes the field illumination a touch.  Not really a big deal since a good flat will address this.  However, with an RC you will introduce off-axis coma.  All that being said, there is no reason the collimation can't be quite stable with these scopes.  I used a 10" RC for a while and it would hold collimation even when transported in a car over bumpy roads, at least most of the time.  Just expect a learning curve.

- If you were thinking of visual use as well as photographic use, I think there are better choices.  The GSO Ritcheys can do very well for photography, but I was never satisfied with the visual, likely because of the size of the central obstruction.  Contrast is quite low.

- You'll need a lot of integration time to go deep at f/8, and you'll want to go deep since the objects these scopes are typically used for are galaxies with the occasional globular, or planetary nebulae sprinkled in.  Some smaller emission nebulae as well.  You want to capture tidal tails around galaxies?  Galactic cirrus/IFN? Reflection nebulae? Dust, dust, and more dust?  A large scope with a long focal length is a great choice.  It's just not an easy choice.  Expect multiple hours of exposure time per image.  

 

Basically, if you are as happy optimizing your scope as you are collecting data, if you get as much joy from the experience of producing an astrophotograph as you do from the photograph itself, if you don't mind creating only a few really good images per year (depending on your seeing conditions), if you really desperately want to photograph galaxies, not just larger objects then a 10" or 12" Ritchey is a very good choice.  Expect a long and steep learning curve, both for optimizing the hardware and data and in processing.  

 

I would recommend one of the truss scopes rather than a solid tube.  In a 12" I don't think you have a choice.  In the 10", you can get either design.  Normally I would recommend a solid tube since it prevents heat rising through the optical path, but the solid tube GSO scopes have a peculiar design for the focuser attachment that can lead to collimation issues with flexure, especially with heavy cameras.  I never had that problem with mine, but lots of other people have run into problems.  Stick with the truss.


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#12 ImNewHere

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Posted 19 October 2017 - 12:32 PM

I haul my 8RC in my car quite often and haven't had to touch collimation.


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#13 Jared

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Posted 19 October 2017 - 12:33 PM

In my experience with owning a GSO RC08, i would not suggest this as a scope for a novice, or just about anyone else. They are difficult to collimate correctly, and very easy to mess up if you don't understand how RCs work, or if you move the primary. They are certainly not like Newts and people get into big messes thinking they will move the primary to collimate like you do in a newt. These scopes are cheap for RCs and attract folks on a budget, but usually you have to spend at least the scope cost again on tools to assist collimation, and focuser collimation rings or replacements.

I would start with something easier. If you have a Celestron background, something like an Edge HD8 gives you advantages over the RC08. Sure it cost more but it is also flat field, long focal length, it is easy to collimate without tools, it stays collimated, with the reducer you can image at f7. The Edge will have excellent resale value, whereas used RC08s are hard to give away because so many people get sick of them.

I would hate to see you have a bad experience.

While I agree with you that collimating them is harder than collimating a scope that has a spherical secondary, I think you may be overstating the case somewhat.  First, one definitely DOES need to move the primary if it's off.  Since the secondary can't be adjusted laterally there just isn't any solution for this.  That being said, you don't need the Tak scope or even a laser collimator as long as you are a little patient and willing to use the night sky and your camera to make adjustments.  It's iterative and a pain in the neck, but it is definitely possible to be successful even without all the extra equipment.  And since the OP is considering a 10" or 12", the Ritchey is flat enough without any additional correction for anything up to a 4/3" chip, the largest most people are trying to use with these moderately priced Ritchey's.

 

The Edge is certainly a nice scope, but all scopes in these size ranges have tradeoffs.  The Ritchey, in my experience, cools faster than an Edge, is much less susceptible to dewing, avoids the issue of mirror flop (which the locks don't fully address since I have been reading recently that they tend to shift the focus), has more back focus available, and has a more stable focus with falling temperatures.  The Edge certainly has some advantages as well.  Cleaning a Schmidt plate is much easier than cleaning a primary, the field is certainly flatter, there is a dedicated focal reducer that seems to work well (if you can find one--constantly back ordered for months at a time), and is certainly easier to collimate.  Also, it's a better scope visually in my experience.  



#14 bobzeq25

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Posted 19 October 2017 - 03:40 PM

Now that I've retired and convinced the wife that I can spend a pot of $$, I've been planning an upgrade in astrophotography from the old Celestron Powerstar C8 to a Ritchey Chretien 10" or 12".  However, I'm now totally confused.  I have found what appears to be exactly the same RC telescope branded GSO (Guan Sheng Optical - who I think actually makes them), or branded TSO (also called TS Optical), or the name of the retailer selling it.  They all appear to have the same diameter, F/ratio, 3 cooling fans, focuser (although there are a few differences), mirror coatings, Losmandy mounts, one of the three designs - carbon Serrurier truss structure - metal tube - carbon tube, among other similarities.  The prices are surprisingly similar as well.  Reviews of them look stellar (ha ha) given the price.  However, it looks to me like I choose (1) the design and (2) the retailer, not specifically whose name is on the RC telescope.  Is that right?

 

Seems like no matter which one except for maybe the metal tube variants, these RC's have been receiving great reviews.  Please advise the RC novice here.

Many inexpensive (<$5K) scopes come from the same factory, and labeled with the vendors choice of name.  They may or may not have differences in things like tubes and focusers.

 

You're correct that choosing a retailer based on customer service reputation can be a good way to go.

 

The debate between the inexpensive RCs and the inexpensive SCTs is mostly a personal deal.  The RCs have fewer and easier to correct aberrations, the SCTs are easier to collimate.  Just a tradeoff, not right/wrong.

 

Personally, I've settled on refractors, which avoids many of the issues.  More than 1000mm in my seeing is usually wasted.

 

You didn't mention the all important mount.  Which is...?


Edited by bobzeq25, 19 October 2017 - 03:44 PM.


#15 PhilHoyle

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Posted 20 October 2017 - 11:19 AM

You might also want to check out Astro-Tech's line of RC's.

 

Phil



#16 TxStars

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Posted 20 October 2017 - 03:07 PM

Astro-Tech's line of RC's" is again the same telescope from a different dealer.

 

If you have a good mount (These are 40-50lb  when all set up for imaging) then a 10-12" RC would be a great scope.


Edited by TxStars, 20 October 2017 - 03:08 PM.


#17 PFitzhorn

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Posted 20 October 2017 - 06:17 PM

 

Now that I've retired and convinced the wife that I can spend a pot of $$, I've been planning an upgrade in astrophotography from the old Celestron Powerstar C8 to a Ritchey Chretien 10" or 12".  However, I'm now totally confused.  I have found what appears to be exactly the same RC telescope branded GSO (Guan Sheng Optical - who I think actually makes them), or branded TSO (also called TS Optical), or the name of the retailer selling it.  They all appear to have the same diameter, F/ratio, 3 cooling fans, focuser (although there are a few differences), mirror coatings, Losmandy mounts, one of the three designs - carbon Serrurier truss structure - metal tube - carbon tube, among other similarities.  The prices are surprisingly similar as well.  Reviews of them look stellar (ha ha) given the price.  However, it looks to me like I choose (1) the design and (2) the retailer, not specifically whose name is on the RC telescope.  Is that right?

 

Seems like no matter which one except for maybe the metal tube variants, these RC's have been receiving great reviews.  Please advise the RC novice here.

 

You didn't mention the all important mount.  Which is...?

 

 

Sky-Watcher EQ8 SynScan GoTo (Orion HDX110) on a Berlebach Planet tripod with double clamps and an EQ8 mount.

 

I appreciate the comments that an RC might not be a good scope for a novice.  I probably generated that assumption based on the forum I originally posted in.  Thanks to Ken the Moderator for moving this to a more appropriate location.  Since I'm a mechanical engineer who has designed and fabricated a variety of mounts and control systems for telescopes as a hobby, and have rebuilt/repaired a variety of SCTs and Newtonians for friends, I'm not too concerned about collimating/using an RC.  I like a good challenge.  Besides - anyone who used an RC for the first time was a novice as well!    Seriously though, I appreciate the answers from the experts about GSO vs TSO vs... for RCs.

Patrick



#18 Ericcurry

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Posted 01 July 2019 - 10:36 AM

I have been toying with the idea of buying a used RC truss tube scope for photography and visual observing , but the above conversation really put me off- rightfully so.

 

it does sound like a very involved process to use the above mentioned style of scope to its fullest.  As I'm only a novice astronomer, it sounds like the technical experience needed is far out of my skill set.

 

Maybe sticking to a nice 8" SCT is a far better choice for just goofing around with photography and observing...  it would certainly be less expensive.

 

that being said, if anybody has or knows of somebody that has a 8" RC truss tube for sale PLEASE do get ahold of me.

 

eric



#19 dhaval

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Posted 01 July 2019 - 11:01 AM

I have been toying with the idea of buying a used RC truss tube scope for photography and visual observing , but the above conversation really put me off- rightfully so.

 

it does sound like a very involved process to use the above mentioned style of scope to its fullest.  As I'm only a novice astronomer, it sounds like the technical experience needed is far out of my skill set.

 

Maybe sticking to a nice 8" SCT is a far better choice for just goofing around with photography and observing...  it would certainly be less expensive.

 

that being said, if anybody has or knows of somebody that has a 8" RC truss tube for sale PLEASE do get ahold of me.

 

eric

RC scopes in general are not great at visual - they have a very large central obstruction. If you plan to do visual, then I would suggest something like the Celestron EdgeHD or Meade ACF F8 scopes. They are excellent for imaging as well. 

 

Another thing, I don't believe GSO manufactures a truss tube 8in RC scope - they are either carbon fiber or steel. 

 

Additionally, GSO manufactured RC scopes that are not truss tube (and even if they are truss tube, but older than a certain time frame) have their primary mirror attached to the focuser. This creates an additional challenge of keeping the mirrors collimated during imaging (especially when shooting close to zenith) and collimation is a general pain for these types of scopes (not difficult, just painful).

 

CS! 




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