Celestron CG-11

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Celestron CG-11
With no fork mount the heaviest piece is 20lbs less than the heaviest Meade LX200 10" piece. The view is appears superior to the Meade 10" (a number of members of our Astronomy club have them). I don't know if it's better optics or the extra inch. Losmandy Mount is great and very sturdy. I see more planetary detail than I do with an AstroPhysics 5".

Fit and finish were excellent. Celestron customer service has been helpful when I had questions. Case that Losmandy sells seperately to fit the mount head does not really fit the mount head. Polar alignment scope worth the extra $.

Overall Rating: 9
Weight: 1 (Unreliable Vote)
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Link to this vote: http://www.excelsis.com/1.0/displayvote.php?voteid=38670

Celestron CG-11
I think for the money you get alot of scope. The Losmandy mount is very nice, but needs some added accesories, which aren't cheap. The clutch knobs are needed to tightnen the clutches down. The Losmandy DSC encorders are needed to use DSC's. If anything of any weight is added to the C11, another counter weight is needed. All in all, the tracking is good. Better than the fork mount and much more versital.
The C11 gives great views for the $$$. A real step up from an 8" SCT. I do find I have to collimate alot more then my previous C8. But planetary views are great when the seeing is good and the collimation is on. Deep sky is much brighter than a C8. This unit is also nice for astro-photos and CCD.

Overall Rating: 9
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Link to this vote: http://www.excelsis.com/1.0/displayvote.php?voteid=38671

Celestron CG-11

G11 mount very sturdy; had some problems with electronics. Bad solder joint on stepper motor assembly caused intermittent dropout of RA. I found and fixed this problem. Also had one of the reversal switches on hand pendant fail; Scott replaced unit pronto no charge. Eyepiece of polar alignment scope, when adjusted to focus reticle, wiggled in scope body causing apparent shifting of star field to reticle, making accurate alignment impossible. Some shim stock fixed this problem, after no response from Scott to Email. Also nylon thrust washer was missing from RA assembly upon delivery from factory; called and Scott sent pronto. This, in my mind, shows sloppy QA for an otherwise excellent product.

C11 was purchased as an OTA from Pocono West. First thing apparent was a glob of orange material on the primary. Also spherical error of system was about 1/2 wave, using Suiter's book. Inside focus diffraction pattern very fuzzy, focus soft. Also an unacceptable amount of mirror shift. Back went the OTA to the factory. The orange glob was the RTV that they use to glue the primary to the cell. The service rep had no idea what the orange stuff was during initial discussion; I found out reading a website discussing the detailed disassembly of the C11. This doesn't give me a warm feeling about the expertise of the service reps. I assume the repair people knew what it was. They "spun the primary" (their words) which means that the primary was rotated relative to the secondary-corrector orientation. I could tell that it was rotated about 90 degrees CW because the cleaning of the orange goop off the primary left a stain on the mirror surface. The mirror flop was cut in half. Star testing the scope showed that spherical error improved to about 1/4 wave, which is about as good as you can expect in an obviously mass produced product; my guess is these are probably average optics for Celestron. In and out of focus patterns are more nearly similar, focus is "snappier." It is too bad that I had to send it back to get it assembled right. Another example of poor QA. Even a cursory final inspection would have revealed the orange RTV. Don't know whether this is a result of Tasco buying into Celestron. The subsequent lowering of the C11 OTA price from about $2000 a year ago (what I paid) to about $1700 now (4-20-00) may hint even more cuts in quality. Cheaper prices are not necessarily a good thing for the consumer when quality suffers.

In spite of the above problems, the C11+G11 is an impressive performer, if you are willing to work through the above mentioned problems.

Overall Rating: 8
Weight: 1 (Unreliable Vote)
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Link to this vote: http://www.excelsis.com/1.0/displayvote.php?voteid=38672

Celestron CG-11
I think this is a great scope for the money. Detail on both planetary and deep-sky is excellent. Image shift isn't bad. The mount is a work of art. Very stable even in moderate wind. I also use it with my long focus 5" refractor. The whole set-up is very portable, it fits in my Escort with plenty of room left over for camping gear. The polar alignment is a breeze to use. Overall I've been extremely happy with the CG-11.

Overall Rating: 9
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Link to this vote: http://www.excelsis.com/1.0/displayvote.php?voteid=38673

Celestron CG-11
My sample shows identical intra and extra focal pattern.

Using the 2:1 ratio test in the slice image mentioned by suiter in his star testing astronomy telescope book gave values of 0.45mm and 0.6mm, this indicates a very well corrected scope. Mars holds power at 777x under steady skies.

Mirror shift is pretty bad but fixed with main mirror lock and JMI secondary focuser.

Overall Rating: 8
Weight: 1 (Unreliable Vote)
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Link to this vote: http://www.excelsis.com/1.0/displayvote.php?voteid=41069

Celestron CG-11
Had this one about 16 years, one of the first black tubes, with special coatings (no silver available then). It is my 5th scope, after 1 refractor and 3 Newtonians. Mounted on an 80 pound tripod from Sky Instruments (Vancouver), the C11 fork is very stable, even at high power. Very small image shift on my unit, focusser is quite good. Added a Telrad and Astromaster. Only complaint is limited range on Dec vernier. After 15 years of moderate happiness with a variety of eyepieces, I'm now using Radian eyepieces for planetary with absolutely thrilling results up to 467x on a good night. Can go to 560x, but seeing very rarely permits it. Widefield deep sky observing is great with an f/6.3 adapter attached. Optically, this is a great scope, especially after a 2 to 3 hour thermal adjustment, which the optics and mechanics seem to like before an observing session. Keep that in mind before checking those diffraction rings! I bet many complaints of their scope's optical quality (reflectors and schmidts in particular) are from people who don't wait for thermal stability. I considered trading it in toward an xxxx-18 dob last year, but after a 3-week evaluation, the C11 weight and optics won that test.

Overall Rating: 9
Weight: 1 (Unreliable Vote)
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Link to this vote: http://www.excelsis.com/1.0/displayvote.php?voteid=41070

Celestron CG-11
Worst scope I have ever owned. The large central obstruction combined with horrid spherical abberration produces fat star images on and off axis. There is a very noticeable brightening to one side of a defocused star test. In addition it needs more cool down time than my 7 inch mak-newt. Planetary images are brighter through the C11, but the mak-newt easily wins on detail and contast. (Case in point, I have never seen the cassini or enke divisions through my C11). I even prefer my mak on deep sky objects. The mak-newt make a wonderful wide field scope and provides pin point star images. I am taking delivery of an Obsession 20 this Sept. and I plan on making my C11 into a lamp in celebration and as a reminder. Friends don't let friends buy C11s. The Losmandy mount has served me well and gets a 8.5 rating the C11 gets a -4.5 hence the overall rating of 4.

Overall Rating: 4
Weight: 1 (Unreliable Vote)
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Link to this vote: http://www.excelsis.com/1.0/displayvote.php?voteid=41071

Celestron CG-11
Worst scope I have ever owned. The large central obstruction combined with horrid spherical abberration produces fat star images on and off axis. There is a very noticeable brightening to one side of a defocused star test. In addition it needs more cool down time than my 7 inch mak-newt. Planetary images are brighter through the C11, but the mak-newt easily wins on detail and contast. (Case in point, I have never seen the cassini or enke divisions through my C11). I even prefer my mak on deep sky objects. The mak-newt make a wonderful wide field scope and provides pin point star images. I am taking delivery of an Obsession 20 this Sept. and I plan on making my C11 into a lamp in celebration and as a reminder. Friends don't let friends buy C11s. The Losmandy mount has served me well and gets a 8.5 rating the C11 gets a -4.5 hence the overall rating of 4.

Overall Rating: 4
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Link to this vote: http://www.excelsis.com/1.0/displayvote.php?voteid=38675

Celestron CG-11
If you can't see the Cassini division with this scope, then you clearly got a lemon, or it was way off collimation. Did you get it checked out?

Overall Rating: No Vote
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Celestron CG-11
I ahve no problems with my C11. I have had it for a Year on a G-11 Mount. This systems replaced an LX200 8", that had excellent optics. The C11 really brings out detailes in clusters and deep sky objects. CCD on planets is great, showing fine detail. Visual contrast, sharpness is also excellent. You must make sure it is collimnated and allow enough time for it to cool down. The large mirrior and closed tube may take a couple of hours to calm down. Also remember, on average to poor nights, a smaller scope will always do better than a large one. When the seeing is very-good to excellent, the larger scope will excel! I do my star testing with an ST5c with the star out of focus. The rings are sharp and you can measure to make sure everthing is centered. I will be adding this information to my web page in the future. http://hometown.aol.com/sampitts/Astrophotography-1.html
Clear Skies : Sam Pitts

Overall Rating: 9
Weight: 1 (Unreliable Vote)
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Celestron CG-11
I've owned a CG-11 for 8 years and have found it to be a generally excellent scope. This wasn't always so. When I received it, the telescope would not come to a sharp focus at above about 80X. Testing with a Ronchi grating confirmed that there were serious problems. Was not impressed with the time and effort it took to persuade the retailer, Perceptor of Ontario, Canada to finally agree to send the scope back, nor with the cursory "coatings stripped, re-coated" that were the only info celestron would give, nor with the three months or so this took, but was with the results. Star images were excellent, even at high power, planetary views quite good and deep sky objects were also very good. Some informal testing showed very good images

My late, dear friend and Father Lucian Kemble used an outstanding specimen of the older orange C-11 on a heavy Byers mount for his many superbly documented observations, in some of which actually exceeded the theoretical limiting magnitude for a a scope of this size. He was quite happy with the performance of mine, which he used to show people Pluto at the Saskatchewan Summer Star Party in 1997 and 1998.

Now, after 8 years of use, the OTA does seem to need some re-collimation and could also stand a bit of cleaning. All in all, I think that the Celestron OTA was a good buy, and that while the company's Quality Control could be better, they did at least do a very good job of fixing things, with a little urging. (All this was, of course, pre-Tasco.)

I have also found the Losmandy mount is basically wonderful, but needed tweaking in a number of areas:
1) the stupid (as Scott himself called them; he claimed that "companies" had forced him to he use them) phone connectors kept shorting or breaking. I fololwed his suggestion and had a friend soldier the motor end
2) the "California grease" used for the mount didn't work for our -20 temps, and also seemed to dry out, so i disassembled the whole mount and I replaced it with lithium grease
3) odd bits like the illuminator for the polar axis scope were stuck on with dangling batteries and over-fine machine thread which soon wore out
4) it was so awkward to add and use 3rd party digital setting circles that I ended up selling them. I wanted them in the first place because the manual ones, though well made, are just a bit too small to use precisely. (Are Losmandy's own any better???)
5) original long legs were awkard to level and use --but Scott's fixed that!

Erich K.
saskatoon, Canada

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Celestron CG-11
The Losmandy G-11 mount is magnificent. It's a mechanical work of art and very solid. The optics are typical Celestron; better than Meade, but could still use some improvement.

Overall Rating: 8
Optics:7 Mount:10 Ease of Use:8 Value:8
Weight: 1 (Unreliable Vote)
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Link to this vote: http://www.excelsis.com/1.0/displayvote.php?voteid=140431

Celestron CG-11
This is not quite a CG-11 but I would like to comment on Celestron products. I have a old and I mean old C-11(orange on a fork mount) bought it new 20 some years ago. It has NEVER HAD ANY kind of problum and has been used many many hours doing astrophotography. I will admit the newer gotos' have advantages. So I feel Celestron products are a good value for their cost. Thank you - Joe Macrie

Overall Rating: 10
Optics:9 Mount:10 Ease of Use:10 Value:10
Weight: 1 (Unreliable Vote)
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Link to this vote: http://www.excelsis.com/1.0/displayvote.php?voteid=313041

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