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Ranking All 30+ Schmidt Cassegrain Telescopes

Rank & ratings last updated by Zane Landers on

Schmidt-Cassegrain telescopes (SCT) were all the rage in the 1970s and 1980s when they were introduced, rivaled only by the Dobsonian telescope in popularity for both newcomers and experienced users. Today, I still see Schmidt-Cassegrain telescopes dominating midsize amateur and research observatories and I commonly see them at astronomy clubs and star parties that I take part in.

However, in today’s world, the SCT faces stiff competition from other telescope designs that are arguably superior in many aspects and thus have less variety than in years past. Gone is the rivalry between Celestron and Meade (went defunct in 2024). Now none of the other telescope manufacturers beside Celestron offers SCTs.

SCT light path with C6 as base
Schmidt Cassegrain Light Path

Schmidt-Cassegrains use two mirrors—one concave and one convex—and a thin, unusually curved Schmidt corrector to achieve sharp images. This corrector may look like a flat window pane but is actually a precise, delicate, and hard-to-replace optical surface.

SCT optics are made in "matched" sets. This means that the corrector is made on what is basically a die. The shapes of the mirrors are then slightly tweaked to make up for any flaws in the way the corrector was manufactured. As such, breaking one of the three optical surfaces means that the other two also have to be replaced.

Most SCTs come in aluminum optical tubes and focus by moving the primary mirror back and forth to adjust the spacing between the mirrors, thus moving the focal plane by huge amounts while not actually moving the mirror very much physically.

A real SCT and its parts
A real Schmidt-Cassegrain cutaway with the parts marked. Image: Zane Landers

Almost all SCTs have standard threads at the back, to which accessories such as star diagonals, focal reducers, or camera adapters can be attached.

I've seen some users also attaching an external Crayford-type focuser to an SCT to provide a slightly stiffer focusing mechanism than the SCT's internal focuser.

What You Should Expect While Buying an SCT

A Schmidt-Cassegrain usually costs at least twice as much as a Newtonian reflector boasting comparable capabilities, if not more, be it a new or used model.

SCTs have very short and stubby tubes. This makes them more portable than basically any non-collapsible reflector telescope of the same aperture. However, the accompanying heavy-duty mount and tripod for an SCT may offset some of this difference in portability.

Because of their internal focusing mechanism and front corrector plate, SCTs are basically sealed internally if caps are kept on the scope.

If the telescope is kept covered, the mirror coatings are at little risk of degradation, provided the instrument is not in an extremely polluted, damp, or dirty environment. The mirror coatings on the oldest Celestron SCTs are over 50 years old, and most will probably last another 50. Most reflectors seldom have their mirror coatings last this long.

If debris or bugs enter our SCT or something breaks internally, solving the problem requires removing the corrector plate, a delicate process that takes steady hands, precision, and all sorts of precautions to re-seat the corrector correctly, or sending the scope back to the manufacturer for loads of money to have them fix it.

How the SCT Design Affects Our Viewing/Imaging Experience

The long focal ratio of SCTs (typically the focal ratio is f/10, with a few f/8 and f/11 models) means they are very easy on cheap eyepieces compared to a fast refractor or reflector, with far less coma, edge-of-field astigmatism, and other problems.

Most SCTs hold collimation better than mass-manufactured reflectors, particularly if the stock collimation screws are kept installed and well-tightened. Replacing the stock collimation screws with thumb screws, which I've seen some people trying, merely exacerbates the need to collimate more often.

Collimating an SCT isn’t insanely difficult but can only be done at night and requires tools and keeping the scope pointed at a bright star. Dedicated laser collimation systems for SCTs are expensive and complicated to use. Collimation only requires adjusting the secondary mirror, as opposed to both the primary and secondary mirrors.

SCTs have basically no chromatic aberration because of their front corrector plate.

SCTs don’t have a spider to hold their secondary mirror, and thus don’t produce spikes on bright stars like a Newtonian reflector or some of the other catadioptric designs out there.

SCTs have large central obstructions because of their big secondary mirrors. This makes the contrast lower compared to Newtonians or Maksutov-Cassegrains, which have lower central obstructions.

The Schmidt corrector is thin, so an SCT will acclimate to ambient temperatures faster than a Maksutov-Cassegrain will.

But compared to a Newtonian reflector, a Schmidt-Cassegrain telescope still requires more time to cool down due to the large secondary mirror also needing to cool down and the corrector plate trapping warm air inside the tube.

Even a moderately sized SCT has a huge focal length (typically f/10). For example, Celestron’s C8 8” optical tube has a focal length of 2 meters (2000 mm)! In comparison, typical 8” Dobsonian reflector telescope has a focal length of only 1200 mm.

At larger sizes, the long focal length becomes a huge issue. A 14” or 16” SCT has a tiny field of view compared to a typical Dobsonian of that aperture.

The long focal length of SCTs means they need more accurate tracking and guiding for astrophotography. An f/6.3 focal reducer helps here.

The long focal ratio of f/10 and such also requires long exposure times, magnifying issues in tracking and guiding when doing deep sky astrophotography. An f/6.3 focal reducer reduces this issue at the expense of possible vignetting with some cameras as well as cost.

But an f/6.3 reducer has its own set of issues.

SCTs actually require a lot of precision to focus due to the extreme curvature of their primary mirrors, which can be a pain when using high magnification or trying to do astrophotography.

To make matters worse, the primary mirror can shift on its rod during focusing, making the target appear to bounce around the field of view. The mirror could also flop over a long period of time, ruining a long-exposure image. This can be alleviated by locking the mirror in place during photographic exposures and/or attaching an external Crayford focuser to the back of the telescope, but either requires a significant amount of monetary expense and/or DIY work.

Older SCTs come on fork mounts or manual equatorial mounts, which require precise polar alignment in order to be used correctly and can be troublesome to aim manually—especially with the narrow field of view of the telescope itself. Newer computerized mounts may be less complicated, but they still frustrate the user and have questionable longevity due to their cheaply made components.

2024 August Update: Orion Telescopes & Binoculars's retail website went offline on July 31st, and their storefronts are all shut down from mid-July. We're in the process of removing Orion's and Meade's (Orion owns Meade) telescopes from our recommendations and rank lists.

Rank Category: SCTs Under $1000

Celestron StarSense Explorer DX 5" Schmidt-Cassegrain
Celestron StarSense Explorer DX 5”
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StarSense DX 5" uses a very compact C5 optical tube, which is Celestron’s oldest SCT model in their lineup, dating back to 1971. With an aperture of 125 mm and a focal length of 1250 mm on the surface, it should be comparable in terms of views to a 6" aperture newtonian reflector telescope. But because its huge secondary mirror blocks 40% of the aperture by diameter, the telescope's actual contrast and resolving power are much lower, and it can only gather light as well as a 4" reflector, not a 6" reflector. The mount is, of course, easy to use thanks to the StarSense Explorer technology. StarSense Explorer technology shows me where my telescope is pointed in the sky by making use of the camera and gyroscope of my smartphone when it is attached to the mount, and then I have to physically move the telescope accordingly. Unlike GoTo, StarSense Explorer doesn't automatically point to and track the object.
Celestron NexStar 5 SE SCT
Celestron NexStar 5SE
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The NexStar 5SE is my least favorite Schmidt-Cassegrain out there, as it is a bit small and full of compromises. But I'd say that it does the job for those who must have an SCT for under $1000. NexStar 5SE uses the same Celestron C5 optical tube as the above-mentioned StarSense Explorer DX 5". The 5SE uses a smaller version of the NexStar SE mount and is controlled with a provided hand paddle. It requires a fair amount of setup, but once working, it automatically slews to any target of my choosing from its database of 40,000 objects and tracks them pretty accurately too. A built-in equatorial wedge to use the scope in an equatorial configuration for long exposure photography is provided, but I felt that it is of little use due to its complete lack of fine movement adjustments in the mount and the C5 optical tube’s inability to properly illuminate a camera sensor with an f/6.3 focal reducer (arguably necessary for long exposures). You should also note that the 5SE is limited to 1.25” only accessories, despite the ability to physically attach a 2” diagonal.

Rank Category: SCTs Between $1,000 and $1500

The 6" SCT shows us a fair amount of detail on the Moon and planets and performs wonderfully on deep-sky objects, especially under dark skies. I can properly resolve globular clusters and view thousands of galaxies, a few dozen of which have some kind of detail visible in them under dark skies.

Celestron NexStar 6SE
Celestron NexStar 6SE SCT GoTo
$1099 at HighPoint
The NexStar 6SE has some of the best value of any SCT package and I even think of it as a reasonable alternative to a 6” or 8” Dobsonian. The NexStar 6SE is a bit chunkier than the NexStar 5SE but offers significantly more capability at only a slightly higher price and in a slightly larger package. A 1” increase in aperture may not seem like much to bother with, but in the case of the Celestron NexStar 6SE, I can confirm that it's a much bigger deal than the specs would suggest. The 6SE's C6 optical tube has significantly more light-gathering ability, resolution, and contrast than the 5SE's C5. The optics tend to be made to a slightly higher standard of quality, and the whole tube is negligibly larger in physical size. I was also able to use the telescope with an f/6.3 focal reducer for photography and a 2” star diagonal for visual, both without suffering from vignetting problems, which I believe provides a huge boost in value too. The 6SE also uses a beefed-up version of the NexStar SE mount with a taller fork arm. All this being true, the scope is still small enough to carry on a plane with the tube attached to the mount! As with the 5SE, only a single 25mm Plossl (60x) and a basic 1.25” visual back, diagonal prism, and red dot finder are included, so you’ll want to add more accessories later on to get the most out of the scope.

Rank Category: SCTs Between $1500 and $2000

Celestron NexStar Evolution 6 Telescope
Celestron NexStar Evolution 6 SCT GoTo
$1679 at HighPoint
The NexStar Evolution 6 adds a lot of bells and whistles compared to the above-ranked NexStar 6SE, but the views are largely the same. The NexStar Evolution 6 uses the same optical tube and hand controller as the 6SE but adds a lot of bonus built-in mechanical features. I also experienced it to be a bit more convenient to set up than the 6SE. The Evolution mount has clutches, which can be unlocked to point the scope manually if power is lost, a built-in rechargeable lithium-phosphorous battery, and can be controlled with either the included hand paddle or my smartphone/tablet. The scope also has an eyepiece rack and is slightly easier to assemble and transport. Like the 6SE, I can bring the tube and mount head assembly as carry-on luggage in a case. It comes with 40mm and 13mm 1.25" Plossl eyepieces, and as with the 6SE, a 1.25” visual back, prism star diagonal, and red dot finder are also included. These accessories are enough to get you started.
Celestron Advanced VX 6" SCT GoTo
List Price: $1799
Rank 2
4/5
I think that the C6 optical tube is best with either a HyperStar unit or an f/6.3 reducer for deep-sky astrophotography, but it is still a reasonable scope to start with and works well on the Advanced VX mount. However, setting up this relatively small scope on a clunky, big, and complicated mount for visual use is simply overkill in my opinion.
Celestron Nexstar 8SE SCT GoTo
List Price: $1599
Rank 3
3.7/5
While we'd still call it a decent pick, the NexStar 8SE’s mount is less than ideal due to its rather small tripod legs and lightweight single-arm fork design. We’d recommend stepping up to the 8” NexStar Evolution if you must have an 8” GoTo scope.

Rank Category: SCTs Between $2000 and $2500

Celestron 8" NexStar Evolution Computerized Telescope
Celestron NexStar Evolution 8 SCT GoTo
$2199 at HighPoint
The NexStar Evolution 8 is my favorite of the various packages Celestron offers its beloved 8” Schmidt-Cassegrain optical tube, the C8, as. I'd skip over the cheaper but popular NexStar 8SE due to its inadequate mounting, and in my opinion, it should be avoided if possible. The 8” Evolution model has the same mount and accessories as the above-ranked 6” Evolution, but the included C8 optical tube provides significantly more light gathering and resolving power than the C6 without significantly adding bulk. The Evolution mount provides a rock-solid support for the 8” optical tube; the same cannot be said of the cheaper alt-azimuth GoTo mounts provided with some other models. The same accessories as the 6” Evolution are provided with the 8” model. However, the C8 would really benefit from a 2” diagonal and accessories to get the widest field possible at low magnifications, so I’d definitely recommend adding one if you can. I also like that the 8” Evolution can still be transported on a plane as with the 6” model, but I need to put the mount head in luggage and only bring the tube as a carry-on.
Celestron Advanced VX 8" SCT GoTo
List Price: $2299
Rank 2
4/5
The Advanced VX 8” isn’t nearly as compact nor convenient as the Evolution 8, but it offers identical views with the perks of some astrophotography capabilities later on. The Advanced VX 8” is simply Celestron’s C8 optical tube (the same is used in the above-ranked Evolution 8) bundled with Celestron's Advanced VX German equatorial mount. The AVX is a computerized GoTo mount that tracks on an astrophotography-friendly equatorial axis instead of an alt-azimuth like the NexStar Evolution. However, setting it up does require more assembly and effort than an alt-azimuth mount. The whole AVX 8" SCT package is a bit more cumbersome to transport as well. But once set up, the Advanced VX 8” works great for lunar and planetary astrophotography. For deep-sky astrophotography with a DSLR or cooled camera, a focal reducer and autoguider are necessary to get good results. So make sure to factor those into your budget as well. Not a lot is included with regards to accessories, and, you’ll want to purchase at least a few additional accessories to get the most out of this instrument, whether it’s for visual astronomy or astrophotography.

Rank Category: SCTs Between $2500 and $3000

Celestron Advanced VX 9.25" Schmidt-Cassegrain Telescope
Celestron Advanced VX 9.25” SCT GoTo
$2949 at HighPoint
Celestron’s 9.25” optical tube packs just a bit more punch than the C8 but without outgrowing you in the process. The Advanced VX 9.25”, like the 8”, can be used for some astrophotography, though the C9.25 is a bit long in focal length and heavy to be used for long exposures with this mount. The C9.25 is just a bit sharper on planets and gathers slightly more light than the 8” model, but only weighs a bit more. The C9.25’s slightly different optical design makes it a bit easier to focus and some claim it has better optics too, though I think this is partly due to the slightly more lax collimation tolerances of the scope. As with the 8” Advanced VX kit, not a lot is included with regards to accessories. The C9.25 is about at the limit of what the VX can hold, and as such it isn’t really usable for deep-sky astrophotography, but shots of the Moon and planets are perfectly doable. From my experience, the AVX mount works best with a scope smaller and shorter in focal length than the C9.25, such as a 4” refractor or 6” Newtonian reflector.
Celestron NexStar Evolution 8 EdgeHD with StarSense SCT GoTo
List Price: $2949
Rank 2
4.1/5
The NexStar Evolution 8” EdgeHD w/StarSense adds EdgeHD optics to the NexStar Evolution 8” package, along with Celestron’s StarSense auto-align technology. Since the Evolution mount isn’t designed for astrophotography, I didn't benefit much from this improvement. These conveniences are arguably not worth the price tag, but it’s a nice scope nonetheless. More significant is the addition of Celestron’s StarSense auto-aligning system, which aligns the telescope with stars without any input from the user—just set it up, level the tripod, and turn it on. The StarSense system does require a completely clear night sky free of clouds or obstructions such as trees or buildings, however. Additionally, with the StarSense technology active, you are limited to using Celestron’s standard SkyPortal app to control the telescope, which lacks crucial features like a red-tinted display option and far fewer catalogued objects. Otherwise, the performance, operation, and accessories are the same as the regular NexStar Evolution 8”.
Celestron CGEM II 800 SCT GoTo
List Price: $2999
Rank 3
4/5
The CGEM II mount makes for a good pairing with the Celestron C8 optical tube for deep-sky imaging. However, visual astronomers will be happier with the more compact and feature-ridden NexStar Evolution 8, while astrophotographers intending to use the C8 XLT for deep-sky imaging might want a larger mount with better tracking and guiding accuracy and/or to opt for the more expensive EdgeHD version of Celestron CGEM II 800 that comes with better field-flattening and mirror locks to improve imaging capabilities.
Celestron Advanced VX 8" EdgeHD SCT GoTo
List Price: $2799
Rank 4
3.9/5
The 8” EdgeHD model is a significant improvement over the regular C8 for astrophotography, though the difference at the eyepiece might be hard to spot. The EdgeHD version of the 8” Advanced VX Schmidt-Cassegrain adds Celestron’s EdgeHD optics, which provide a significantly flatter field and sharper images than the standard C8 8” Schmidt-Cassegrain. It is designed with imaging in mind thanks to its equatorial mount and EdgeHD optics. Though the Advanced VX is a bit on the light side for serious imaging with an 8” telescope, it will do the job. The views are splendid, too. For visual astronomy, you probably won’t notice a huge difference from the regular 8” SCT model besides a slightly improved cool-down time for the optics, but the EdgeHD’s flattened field is helpful for long-exposure astrophotography. As with the regular version, however, for best results, an astrophotography setup really requires a focal reducer, autoguiding, and a polar scope for easy and accurate polar alignment.
Celestron NexStar Evolution 9.25 SCT GoTo
List Price: $2849
Rank 5
3.9/5
The NexStar Evolution 9.25” is actually a bit harder to grapple with than the Advanced VX 9.25” package, but the actual process of setting it up is a bit simpler and the scope is overall just a bit easier to use. The NexStar Evolution 9.25” has all of the same features and accessories as the Evolution 6” and 8” models, but with the addition of the C9.25 optical tube. However, the C9.25 is a bit big for the Evolution mount, and the mount has been accordingly beefed up by including a heavy-duty tripod. If you prefer the simplicity and convenience of the Evolution mount compared to the less cumbersome Advanced VX mount, the NexStar Evolution 9.25” is for you.
Celestron CPC 800 GPS SCT GoTo
List Price: $2599
Rank 6
3.8/5
The CPC 800 is a little less fancy than the 8” NexStar Evolution, but comes on a beefier mount and can be used for astrophotography on an equatorial wedge (sold separately).

Rank Category: SCTs Between $3000 and $6000

Celestron 9.25" CGX 925 EdgeHD Computerized Telescope
Celestron CGX 925 EdgeHD SCT
$5299 at Agena
While perhaps a little overkill for visual use, the Celestron CGX makes for a rock-solid platform for imaging with the EdgeHD 9.25” optical tube and an f/7 reducer, while also being fairly good for visual observation without too much complexity or bulk and an easy user interface with its hand controller.
Celestron CGX 925 EdgeHD SCT
List Price: $5299
Rank 2
4.6/5
While perhaps a little overkill for visual use, the Celestron CGX makes for a rock-solid platform for imaging with the EdgeHD 9.25” optical tube and an f/7 reducer, while also being fairly good for visual observation without too much complexity or bulk and an easy user interface with its hand controller.
Celestron CGX 800 EdgeHD SCT
List Price: $4099
Rank 3
4.6/5
The Celestron CGX is more than adequate for astrophotography purposes with the EdgeHD 8” optical tube, and is usable for a variety of imaging and visual tasks at f/2, f/7, native f/10 or with a Barlow lens for a longer f/raito. However, the CGX is capable of supporting the larger C9.25 EdgeHD too.
Celestron CGX 1100 EdgeHD SCT
List Price: $6399
Rank 4
4.5/5
The Celestron CGX mount is more than enough to hold the C11 or EdgeHD 11 optical tubes for visual observation and decent enough for long-exposure deep-sky astrophotography, though a beefier and probably permanent mount would be more ideal for the job. The views through this scope are a delight too.
Celestron CGEM II 1100 SCT
List Price: $4599
Rank 5
4.4/5
The Celestron CGEM II makes for an ideal mount for the C11 XLT for visual astronomy and planetary imaging use, being much sturdier than the Advanced VX and more compact than the CPC or larger CGX mounts. Neither the scope nor CGEM II is ideal for deep-sky imaging, but the C11 XLT is a fabulous scope for the visual observer or planetary imager.
Celestron CPC 1100 SCT
List Price: $3999
Rank 6
4.4/5
The CPC 1100 is the largest telescope Celestron offers in an alt-azimuth mounted fork configuration, and for good reason. The 11” Schmidt-Cassegrain optical tube is already huge and bulky, and combined with the CPC fork mount, it makes for a downright intimidating telescope. However, the C11 optical tube offers unmatched views of the Moon, planets, and deep-sky objects compared to smaller instruments, provided you can fit them into its relatively narrow field of view.
Celestron CPC 925 SCT
List Price: $3299
Rank 7
4.3/5
The CPC 9.25 is bulkier and heavier than the NexStar Evolution 9.25” but is significantly more sturdy. The CPC fork mount is simpler to set up than an equatorially-mounted configuration of the C9.25 XLT optical tube, though it’s of course a lot heavier and less versatile. You should probably consider an equatorial mount for the C9.25 XLT regardless of what you plan to do with it, but of the alt-azimuth C9.25 and mount configurations, the CPC is definitely the better choice.
Celestron CGX 925 SCT
List Price: $4199
Rank 8
4.2/5
The regular Celestron C9.25 is not ideal for deep-sky astrophotography compared to the EdgeHD version, and the CGX mount is overkill with this scope for visual use. As such, there’s not much of a point in purchasing, though the CGX makes for a fine mount with plenty of capabilities.
Celestron CGX 800 SCT
List Price: $3799
Rank 9
4.2/5
The Celestron C8 XLT is extremely overmounted for visual use on the CGX while being sub-par for deep-sky astrophotography compared to the EdgeHD or RASA designs. As such, while there’s nothing inherently wrong with the scope, we do not recommend this combination as highly compared to those options.
Celestron CGEM II 800 EdgeHD SCT
List Price: $3399
Rank 10
4.1/5
The Celestron CGEM II can technically carry the 8” EdgeHD optical tube for deep-sky imaging, but it’s subpar for the job compared to other mounts with stepper motors, and overkill for visual use compared to the Advanced VX (the EdgeHD optics are also unnecessary for the task).
Celestron CPC 1100 EdgeHD SCT
List Price: $5099
Rank 11
4.1/5
The Celestron EdgeHD optical configuration offers few perceptible advantages over the regular C11 XLT for visual use or planetary imaging, but the CPC fork mount is not exactly the best for deep-sky astrophotography, even when paired with a wedge and autoguiding. It also possesses the same extremely bulky and heavy frame as the regular CPC 1100 model, which may be uncomfortable for many users to set up or transport.
Celestron CGEM II 925 SCT
List Price: $3399
Rank 12
4.1/5
The CGEM II is somewhat overkill for holding the C9.25 XLT for visual use while being completely insufficient for deep-sky astrophotography with such a big scope. However, it is a little steadier than the Advanced VX if you demand more rigorous requirements.
Rank 13Celestron Advanced VX 11″ Schmidt-Cassegrain3.9
Rank 14Celestron CGX-L 9.25 SCT3.8
Rank 15Celestron CGEM II 925 EdgeHD3.8
Rank 16Celestron CPC 925 EdgeHD SCT3.6
Rank 17Celestron CPC 800 EdgeHD SCT3.6
Rank 18Celestron Advanced VX 9.25″ EdgeHD SCT3.5
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