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Celestron Schmidt/Maksutov Cassegrain Scopes

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#1 RickyD85

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Posted 23 April 2019 - 08:26 AM

Hi

Am in the market for either a 9.25 or 11 inch aperture celestron telescope. Have been looking at the Celestron Schmidt Cassegrain and Maksutov Cassegrain telescopes.

Will be doing visual observations only so no astrophotography.

What is the basic difference between the countless Celestron models? Edge, CPC, CGX, CGEM, Advanced VX!?

There are so many different models and apart from the mounts I do not really understand the difference between the scopes themselves.

Which model is best for visual astronomy?
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#2 Procyon

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Posted 23 April 2019 - 09:51 AM

How many lbs or kg can you bench press press or lift and will the telescope be stored for quick access or up or down a few flights of stairs. Bigger is better but weight can be a big issue.

 

All will make great visual only scopes, the CPC will be the heaviest probably, but also the sturdiest, that's why I love mine.


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#3 rkelley8493

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Posted 23 April 2019 - 09:23 AM

A lot of the optical tubes are the same, but they are mounted on different mounts & tripods. CGX, CGEM, and Adv VX are names of the mounts [from most to least expensive in that order], and all of those are Equatorial Mounts. Edge & CPC are optical tubes, also from most to least expensive, with the Edge being "coma free". But since "coma free" is registered trademark, they use "Edge HD" instead, but it basically means the same thing.

Best for visual astronomy? I'd say go with the CGEM 2 mount which is solid enough to last you a lifetime, and you can always change out the optical tube for any other scope regardless of dovetail style [Vixen or Losmandy] mount bracket. If I could start all over, that would be the route taken. I went with the fork-mount design, which is great & solid, but there is no changing optical tubes without some serious disassembly.

Best optical tube for visual? I'd say the Maksutov would probably give you sharper images with better contrast, but the cool down time on those is notoriously long. 9.25" SCT would be easier to handle and faster cool down, and 11" is where you start to need an extra hand when setting up for the night. Not that it's extremely heavy, it's just awkwardly large and tough to get your arms around.


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#4 Migwan

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Posted 23 April 2019 - 09:39 AM

OTA:  Edge more $$$ with flatter field (edge of field in focus with center) than CPC (edge of field not quite in focus with center).   For visual, many feel that CPC is good enough.  For AP, Edge is better with one exception.  The 9.25 has no dedicated reducer.  8 and 11 do.  Edges are good for visual, too and are preferred by some.

 

Mounts:  CPC, Evolution are alt az mounts.  The former is fork mounted.  The latter has one arm.  If AP is desired, a wedge is necessary.

 

 CGX, CGEM, Advanced VX! are GEMs and very desirable for AP.  Less so (IMO) for visual, but will do the job just fine.  

 

 

If you google CPC vs Edge there are threads and other info that you can research.   Example

 

Good luck.  jd 


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#5 RickyD85

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Posted 23 April 2019 - 09:21 AM

If it's a complicated answer, happy if you just tell me which model to buy for visual astronomy! laugh.gif



#6 rkelley8493

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Posted 23 April 2019 - 10:22 AM

Sorry for the dozen replies... CN kept freezing up on me every time I would hit Post [deleted the duplicates]


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#7 rkelley8493

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Posted 23 April 2019 - 10:39 AM

If it's a complicated answer, happy if you just tell me which model to buy for visual astronomy! laugh.gif

For visual, the easiest one to use would probably be the CPC or Alt-AZ model mounts. The CPC is an all-in-one solution, great because it has all you need in one package. However, there will be no room to upgrade in the future if you decide you want to change optical tubes, and you would have to get a mount adapter for astro-photo. I have the LX90, Meade's version of the CPC, and it's great for visual, but I am starting to notice flaws in the tracking, go-to, and mounting assembly. Since it's an all-in-one, it affects the whole assembly. I wish I could put the OTA on my Orion Atlas mount, but in order to do that, I would have to demount the fork arms and install a dovetail bar, and all that just isn't worth the hassle. 


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#8 Procyon

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Posted 23 April 2019 - 11:03 AM

If it's a complicated answer, happy if you just tell me which model to buy for visual astronomy! laugh.gif

Hi there, you can also read these threads, there might be a few good answers to your questions in there.

 

https://www.cloudyni...11-for-old-men/

 

https://www.cloudyni...truss-tube-dob/

 

https://www.cloudyni...vs-cpc-1100-hd/


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#9 RickyD85

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Posted 23 April 2019 - 04:03 PM

Thanks for all the great info and links, it’s given me a good head start 

 

So i’m pretty set on the CPC 1100 HD. Not sure how much benefit the 11 inches will give over 9.25 for visual astronomy?

 

Happy to deal with the extra weight, I could do with the exercise grin.gif



#10 Bill Barlow

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Posted 23 April 2019 - 04:53 PM

The C11 will be enough of a jump for visual use over the C9.25 (41% more light grasp) to be noticeable, especially for more distant galaxies and galaxy groups.  And not too much additional weight to manage.  The slightly different optical design of the C9.25 might favor that scope with possibly better visual views, but it is the luck of the draw if you get a very good optical sample of either scope.

 

Bill


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#11 Cpk133

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Posted 23 April 2019 - 06:25 PM

I have the 9.25xlt non edge and visually it's an excellent scope.  I wouldn't trade it for a random C11.  I'm a big fan of the modularity of GEM mounts even if there's a little more PITA factor.  Maybe you get the 11 and want to trade down to an 8, not a problem.  Maybe you want to add a frac, to try some astrophotography, no prob.  Maybe you need to send the mount back for service, much easier/safer to send a GEM head than send that big anchor and the optics  It's also easier to pack.  The list goes on and on.  The only advantage to the fork is its easier to sit in one place while you observe.  If you go alt az, look long and hard at the Evolution 9.25 so it's at least modular.  


Edited by Cpk133, 23 April 2019 - 06:28 PM.

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#12 RickyD85

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Posted 24 April 2019 - 01:38 PM

Does anyone know a good resource that shows unfiltered ‘raw’ images taken through a 9.25 and 11 inch scope of the same type? Preferably Celestron models.

I’m relatively new to astronomy, having started via binocular viewing. I want this scope for the occasional very detailed view of the moon and planets and know what I can expect there (have taken my binos to 110x on moon and planets), however I would be interested in seeing raw images taken through the eyepiece of DSO’s, galaxies, globular clusters.

Knowing what to realistically expect to see will help choose between 9.25 or 11 inch. If it really makes a difference would even consider one of the 14 inch models.

Edited by RickyD85, 24 April 2019 - 01:39 PM.


#13 mconnelley

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Posted 24 April 2019 - 02:08 PM

Hello:
 

   I found the CPC 11" to be really heavy, especially when lifting it in its case.  As a point of reference, I normally use a 20" scope (which is also a heavy lift).  We deforked the CPC 11 and put it on a Losmandy mount and I really like it that way.  I prefer finding things on my own, and no one part weights too much.  I don't find it very hard to lift and mount the 11" tube on the mount.  I will say that getting a tip-in saddle plate really helps.  While a C14 is a real handful, I find the C11 quite manageable.  

 

   I expect the visual difference between a C9.25 and a C11 to be fairly subtle.  To me, a factor of 2 in aperture (i.e. going from 10" to 20") is what's needed to have a big enough impact to make it worth getting a larger scope.  The difference between a C9.25 and a C14 would be quite clear...in cost, stability on a mount, your back pain, etc.  

Cheers

Mike


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#14 dakinemaui

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Posted 26 April 2019 - 10:46 AM

I'm not aware of any calculators that have raw/realistic images. A local club's star party may be a good resource.

 

Failing that, there are field of view calculators that will give somewhat of an indication, but most will superimpose different circles on the same scale image. In practice, the opposite occurs -- the image gets bigger within a given area. With visual use, a 5 mm eyepiece is probably the lowest you'll go for most objects, so dial that in to the calculator for something representative. (This yields a magnification 2x the aperture for an F/10 instrument, usually quoted as a reasonable limit.) Brighter objects like the moon & some planets will support more magnification, however.

 

Brightness is the hardest thing to subjectively compare. It's true the C11 will pull in 41% more photons than the C9.25 (square of the aperture ratio), but since the eye's response is nonlinear, it will seem to be only 12% brighter at the same image scale. (Goes approximately as the aperture ratio to the 2/3 power.) Noticeable, but not WOW. It's also a bit difficult to relate "seems 12% brighter" to a picture in your mind, which is where a star party would be invaluable.

 

Alternatively, the scene will appear 19% larger at the same brightness. Again, noticeable but probably meh.

 

Resolution will be about the same, assuming atmospheric seeing is the limiting factor. You would have to be at one of the best places in the world with 0.5 asec seeing before you would even start to see a difference in resolution.


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#15 Spikey131

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Posted 26 April 2019 - 11:34 AM

Some considerations:

 

9.25” CPC, OTA plus mount:  58 pounds

11” CPC, OTA plus mount:  65 pounds.

 

Both of these pretty much require 2 people to set them up.  Will you have help?

 

9.25” OTA only:  21 pounds

11” OTA only 28 pounds.

 

So if you get a set up with a GEM mount, you can carry the OTAs separately from the mount.  So things are a lot lighter.  But can you lift a 28 pound bucket of glass and slide it onto a mount by yourself?  

 

The Edge HD series have optical advantages that were chiefly developed for astrophotography.  Many do not consider these advantages necessary for visual astronomy.  So the XLT versions are adequate for visual.  Like most topics on CN, some will disagree with this.

 

Both scopes have long focal lengths which will offer up narrow fields of view compared with similarly sized Newtonian reflectors, and much narrower than (smaller) refractors.


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#16 Spikey131

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Posted 26 April 2019 - 12:12 PM

So which would I get?

 

If I was mounting it permanently, the XLT CPC 11.  

 

If I had to set it up alone?  9.25 XLT on a GEM.  Any GEM but the AVX, which is too light for that scope.


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#17 Procyon

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Posted 26 April 2019 - 12:35 PM

Found this nice old comparison review between a 9.25 and an 11" SCT. Might be interesting to some, nice read anyhow:

 

https://www.cloudyni...-c-11-xlt-r1419


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#18 Cpk133

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Posted 27 April 2019 - 10:20 AM

So which would I get?

 

If I was mounting it permanently, the XLT CPC 11.  

 

If I had to set it up alone?  9.25 XLT on a GEM.  Any GEM but the AVX, which is too light for that scope.

AVX works perfectly fine for visual or lunar/ planetary imaging.



#19 Cpk133

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Posted 27 April 2019 - 10:36 AM

Does anyone know a good resource that shows unfiltered ‘raw’ images taken through a 9.25 and 11 inch scope of the same type? Preferably Celestron models.

I’m relatively new to astronomy, having started via binocular viewing. I want this scope for the occasional very detailed view of the moon and planets and know what I can expect there (have taken my binos to 110x on moon and planets), however I would be interested in seeing raw images taken through the eyepiece of DSO’s, galaxies, globular clusters.

Knowing what to realistically expect to see will help choose between 9.25 or 11 inch. If it really makes a difference would even consider one of the 14 inch models.

If your visual observing priority is the moon and planets, you're going to be limited by seeing conditions more than the scopes you mentioned. Depending on how much time you have to setup and cool down, you might be better off with a 120ed refractor.  The bigger the scope, the more difficult it is to achieve and maintain thermal equilibrium.  In a perfect world, the biggest aperture is best, but it's not that easy.



#20 rkelley8493

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Posted 27 April 2019 - 12:18 PM

Does anyone know a good resource that shows unfiltered ‘raw’ images taken through a 9.25 and 11 inch scope of the same type? Preferably Celestron models.

I’m relatively new to astronomy, having started via binocular viewing. I want this scope for the occasional very detailed view of the moon and planets and know what I can expect there (have taken my binos to 110x on moon and planets), however I would be interested in seeing raw images taken through the eyepiece of DSO’s, galaxies, globular clusters.

Knowing what to realistically expect to see will help choose between 9.25 or 11 inch. If it really makes a difference would even consider one of the 14 inch models.

Planets & moon will be very sharp [once the scope is cooled down]. You will have more contrast on Jupiter on moonless lights and be able to make out several cloud belts. Great Red Spot comes and goes because of Jupiter's fast rotation. I've only seen it a couple of times. Mars will have dark patches similar to the moon, but it's on a crazy schedule due to its orbit [only good seeing every other year]. Galaxies and nebulae are going to look like gray clouds. The larger the aperture, the brighter the clouds will be and the more detail you'll be able to make out. I can make out the S shape of Bode's Galaxy and the Whirlpool Galaxy in a 10" SCT. The Orion Nebula has a little color to it, almost like a greenish tint, but for the most part, DSO's will be gray. Those color photos you see are because of the filters used and long exposure photography. Gray spiral clouds aren't any less beautiful to me though. Just like a beautiful woman with no makeup lol.gif



#21 rkelley8493

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Posted 27 April 2019 - 12:35 PM

This simulator is pretty accurate. Enter your scope's aperture/focal length & the eye piece FOV/focal length, and it will give you a pretty good idea of what you'll be able to see.

 

https://www.stelvisi...cope-simulator/




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