Celestron 11" SCT optical tube, CG5/AVX dovetail


Availability: More on the way

This 11" aperture aluminum Fastar optical tube has ultra-high transmission Starbright XLT multicoatings and a dovetail bracket for installing it on Vixen style saddles like those included in the newer Advanced Series mounts as well as the older CG5s.
Our Product #: C11OTA5X
Celestron Product #: 91067-XLT
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Product Description

This 11" Celestron Schmidt Cassegrain optical tube is 24" long and weighs only 27.5 lbs.(due to the aluminum tube construction), making it easy to transport. It has an 11" aperture, a 2800mm focal length, and a focal ratio of f/10. An optional focal reducer is available to bring the focal ratio down to f/6.3 for CCD and 35mm photography. Optical performance is guaranteed to be diffraction-limited.

Advanced high transmission Starbright XLT optical multicoatings are standard equipment. This coatings package includes high reflectivity multilayer aluminum mirrors enhanced with titanium dioxide for high reflectivity, plus a unique combination of magnesium fluoride and hafnium dioxide antireflection coatings on both sides of the Schmidt corrector lens. The corrector lens itself is made of high transmission water white float glass instead of conventional soda lime glass (which has 3.5% lower transmission) used in other telescopes.

Starbright XLT multicoatings visibly increase the contrast on subtle lunar, planetary, and nebula details when compared with a scope with standard multicoatings. They also give you higher light transmission for brighter deep space images and shorter exposure times during CCD and 35mm photography. Across the total visual/photographic spectrum from 400nm to 750nm, independent laboratory tests show the new Starbright XLT coatings are 16% brighter overall than even the original industry-standard Starbright multicoatings.

The optical tube comes with a big 9 x 50mm straight-through achromatic finderscope and mounting bracket. The finder has a wide 5° field of view. It focuses by loosening the trim ring behind the objective lens cell, screwing the lens cell in or out to focus, and tightening the trim ring to lock in the correct focus. Also standard is a removable 1.25" visual back that holds visual accessories such as a star diagonal, tele-extender, etc. A 1.25" prism type star diagonal is also standard, as is a 1.25" 40mm Plössl eyepiece. This eyepiece provides a magnification of 70x. Its field of view is 0.68° across, over a third wider than the full moon. Dust covers for the optics are also supplied.

A 1.75" wide dovetail slide bar runs the length of the tube for mounting the optical tube on a Celestron AVX Advanced Series go-to mount, or any mount using a Vixen-style mounting dovetail.

Tech Details

Aperture 11"
Binary and Star Cluster Observation Very Good
Focal Length 2800mm
Focal Ratio f/10
Galaxy and Nebula Observation Very Good
Heaviest Single Component 27.5 lbs.
Highest Useful Magnification 560x
Lunar Observation Very Good
Weight 27.5 lbs.
Planetary Observation Very Good
Resolution 0.41 arc seconds
Visual Limiting Magnitude 14.7
Warranty 2 years


Review by:
12 years ago or so I purchased a Celestron 8"SCT from Astronomics and still have it to this day. I have used this telescope regularly for all these years and have no complaints with it. Back in 2010, I built a 10'X16' roll off roof observatory on my property in Mayslick KY. This site has fairly good skies with a limiting magnitude of about 4.9 to 5.5 depending on the seeing for any particular evening. After its completion, I began to lust after a bigger scope and began saving for an 11" Celestron. Well, that dream finally came to be true a week ago as I received my C11 and proceeded to install it on my Orion Atlas EQ-G mount in my observatory.

I must say at this point, that to truly understand a review of any telescope, one must have some experience with another telescope of any kind, preferably with the same optical design. Therefore I feel that with my 12+ years of using the C8, I am more then qualified to tell you that the difference between the 2 scopes is like night and day (Pun Intended). Objects appear much brighter, on the order of maybe .5 to .7 magnitude, much crisper focus (when properly collimated), and, when used with the 6.3 reducer/corrector, much sharper images out to the edge of the field. I must say that saving for and finally purchasing this telescope was more then worth the wait!

First light was yesterday, in the wee hours of the morning (May 15th 2013 at 3:00AM). After performing a 3 star alignment (which, by the way, was surprising in and of itself by how easy it was to find and center the 3 stars of the alignment), my first object was M51, the Whirlpool Galaxy. Now I have looked at this object for countless hours, thru other telescopes of varying sizes and quality, over the many years I have been involved with this wonderful hobby, but I must tell you, that upon first viewing M51, it literally took my breath away! Both M51 and its companion, NGC5195 were brighter and showed more detail then I have ever seen, barring those in a photograph. The spiral arms were clearly visible and the connection point between the 2 was plain to make out. The only thing missing was color, but we all know that this is not possible due to the limitations of the human eye on extended objects. I must have sat there for 10 or 15 minutes just gaping at this beautiful specimen that was displayed in my 15mm Televue Panoptic eyepiece.

Tearing myself away, I then went to M13 (my other most loved DSO) and again I was dumbfounded at the resolution of this fantastic globular cluster. Not only were there more clearly visible outer stars but I was able to discern stars almost to the center! I'm telling you, this thing looked 3D to my eye!!! Now, I've photographed M13 many times with various cameras and modified web cams, and only a couple of them could rival the real time image that now appeared before my eye. It is not to say that the C11 will provide images that can rival photos on a regular basis, but on this night, on M13, it certainly came close. I am now looking forward to trying my hand at imaging thru this scope to see how well it will do photographically. I firmly believe that it will deliver wonderful images in that medium as well as it does visually.

I observed many more objects that early morning until the sky began to brighten at around 5:30AM, much to my dismay, for I was in no way finished enjoying this incredible work of modern telescope technology. This telescope is built very well for a mass produced product, with fit and finish that I believe have no rivals for its class. The focus has a very positive feel and I could not perceive any noticeable image shift due to mirror slippage. With my C8 this was something that occurred quite frequently. Everything about this telescope exudes quality, attention to detail, and modern design.

If you are considering upgrading an older, smaller telescope, I believe that you will mot have any buyers remorse about spending the money on the Celestron C11 SCT telescope.

Oh, and by the way, the folks at Astronomic are some of the best in the business as far as product knowledge and customer service are concerned. They will go out of their way to make sure that you are satisfied with your purchase. I should know, I have been one of their satisfied customers since the early 90's and have bought just about all of my astronomical gear from them and I will continue to do so. Kevin "Scopefreak" Vaught (Posted on 8/4/2017)
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Supplied Accessories

  • Starbright XLT multicoated optics
  • 40mm 1.25" Plössl eyepiece (70x)
  • 1.25" visual back
  • 1.25" prism-type star diagonal
  • 9 x 50mm straight-through finderscope
  • Dust covers
  • Dovetail bracket for mounting on Celestron CG5 and Advanced Series go-to, Meade LXD75, and Vixen Sphinx and Great Polaris mounts