The Celestron CGX, while being a new, innovative design in the world of astrophotography mounts, still shares some features with its EQ6 style predecessors, and as such, there are still some basic technical specs that you should know.
The CGX has a weight capacity of 55 lbs, or 25 kilograms, which is far improved over the EQ6-R or CGEM, being 5 and 7 kg more, respectively. This means you’ll be able to load the CGX with far more weight while still getting good guiding. However, this number can sometimes be difficult to interpret.
Unfortunately, Celestron, along with most mount manufacturers, is not very specific as to how much weight on the mount is acceptable for specific purposes and how it affects the tracking and guiding accuracy of the mount. It is commonly accepted amongst astronomers that if you are doing visual observing or planetary astrophotography, you can load up the mount to the weight limit or even exceed it by a few kgs, as small-scale errors are not very noticeable visually. In contrast, when you are taking images, the mount’s tracking accuracy has to be far more precise because the images you take will show streaking easily. Adding more weight to the mount can increase the magnitude of tracking errors and ruin any images you would take. As such, we recommend using no more than ½ and ⅔ of the supposed weight capacity for astrophotography. It is important to keep in mind that this is a very broad statement, and tracking/guiding accuracy depends on many factors that are too numerous to list here.
The mount accepts both Vixen V (narrow style) and CGE or Losmandy D (wide style) dovetail plates, which allows you to use any telescope that has a standard mounting system with the CGX, provided you can balance the mount with enough counterweights and keep the weight on the mount under around 25 kilograms.
The CGX also includes a Nexstar+ hand controller. It is the standard hand controller used across all of Celestron’s computerized mounts. It includes over 40,000 objects with Messier, NGC, IC, and custom coordinates for finding any target in the sky that you choose.
The CGX weighs 20 kilograms, not including the tripod, which is also somewhat heavy at 8.7 kg. This can be somewhat of a problem for people who want to use the mount, as 20 kilograms is quite heavy, but this is necessary for the mount to withstand strong wind gusts and vibrations while keeping images sharp. If you get a good grip on the mount, it isn’t too hard to move. The built-in carry handle helps.
The CGX uses a standard ¾” diameter counterweight bar and thus accepts any of the weights designed to fit this size, such as the two included 17-lb counterweights as well as smaller 11-lb and 7 lb units designed for other mounts. It runs off DC power, but you can purchase an AC adapter.
The CGX is packed full of new features and overall improvements compared to other mounts. Celestron listened to its user base and remedied many of the issues and concerns found with mounts like the CGEM and AVX, not to mention adding new and improved features, which we will now list.
For starters, the CGX comes with belt-driven and spring-loaded worm drives, an incredible upgrade over the CGEM that will greatly improve guiding accuracy. Mounts like the EQ6 and CGEM use gears to connect the motor to the worm drive (the most important gear you will find in a mount), which can create problems where too much space is between the gears, causing an issue called backlash.
Backlash can be seen during guiding. It effectively makes some guide pulses ineffective, as any corrective action is stuck in the gap between gear teeth.
A belt drive cuts out the middle gear and instead connects the motor to the worm gear with a toothed belt, which eliminates all backlash. The worm gear is also spring-loaded, which ensures it is well-tensioned. This also reduces backlash and makes adjusting the spacing manually not necessary. Luckily, the CGX comes with belts preinstalled, whereas in mounts like the EQ6 and AVX, belts were something you had to manually install, and worse, in the CGEM, you had no option to install belts at all.
The CGX features a homing system. This is a system where the mount can locate its “home” position without any external input, which is where the mount rests when not pointing at anything. Homing moves both mount axes (Right Ascension and Declination) automatically to their home positions without any sort of outside input. This is especially helpful for observatory systems where the mount is always polar aligned but you may not have access to the mount. With homing, you would be able to be sure of the mount’s positioning without something like plate solving or star alignment. Homing is a rarely seen feature in mounts at this price point and is a premium feature found in the CGX, sure to make the lives of astrophotographers easier.
The CGX features a completely new, redesigned polar alignment base plate. In the CGEM, when you tried to adjust the azimuth polar alignment, the mount would stick and skip, making it impossible to align the mount closely to the celestial pole. With the new and improved polar alignment plate, the amount of friction between the mount head and tripod has been greatly reduced. It also features improved adjustment knobs, which make alignment far easier than with the awkward, circular knobs found on the CGEM.
The mount is also able to go all the way down to 3 degrees latitude and a maximum of 65 degrees, which allows you to use the mount in locations very close to the equator and very far from it.
The CGX, of course, is Celestron’s best astrophotography mount yet. There are some features listed above that make this an excellent mount on the inside, but the CGX also includes some great features that make the mount a joy to use in the field. As with any other Celestron mount, the CGX works with the StarSense AutoAlign, SkySync GPS, and SkyPortal WiFi adapter accessories. If you don’t want to use WiFi or a PC to control it, you can use a NexStar+ controller instead.
The CGX has full computer control and support, based on the new Celestron PWI software/interface. The PWI software allows you to completely bypass the hand controller, which becomes an unnecessary step when you are doing deep space astrophotography. With PWI, the time-consuming step of entering the time and date into the hand controller is not necessary either. This is thanks to the CGX’s included USB Type B port, which allows you to connect directly to the mount without a hand controller or adapters—just get the suitable cable, and you are good to go.
Celestron PWI is a fully functional planetarium software that is built around CGX support. With this software, you can see where the mount is pointing in real time. It also allows you to update the mount’s positioning model without having to do any star alignment via plate solving.
Luckily, the PWI is also ASCOM compatible (ASCOM is an open-source program that allows devices to communicate with software), which means the mount is controllable with any standard image capture programs, for example, SGP, NINA, APT, and other similar programs, which you can use to plate solve (align your mount via images of stars), slew to various targets, and perform meridian flips automatically.
Using the CGX for Visual Astronomy & Planetary Imaging
The CGX mount is sure to make visual observation a joy. The mount uses the Nexstar+ hand controller, which is, in our opinion, superior to the Skywatcher and Orion alternatives as it is easier to use, which becomes an important factor late at night. You can use a very large 14” SCT or similar Cassegrain or a 12” Newtonian atop the CGX for visual and planetary imaging purposes; these are some of the largest non-Dobsonian scopes available on the consumer market.
The Nexstar+ hand controller also includes over 40,000 objects in its database and an internal time clock, which means that you do not have to enter the time and date every time you start up the mount if you choose to enable it. The pointing accuracy of the mount after a 3-star alignment is also excellent. The controller includes nine slew rates for intricate and accurate slewing and pointing, which means you can go from rate 9, which moves the mount several degrees per second, to rate 1, moving at half the speed of the stars. The Nexstar+ also includes a red backlight, which lights up the text on the hand controller without ruining your night vision, meaning you can slew the mount around with ease at night.
The CGX includes a built-in polar alignment feature/routine, which is incredibly useful for visual observers. It calculates your alignment error based on your three-star alignment, which is incredibly useful for observers who do not want to use the polar scope, or those who have no clear view of the celestial pole.
The CGX can take a very high amount of weight for visual use, but that also means that the mount itself is fairly heavy. This becomes a major issue that you will have to think about if you want a mount with such a high payload capacity as the CGX.
Using the CGX for Deep-Sky Astrophotography
Thanks to many new features and improvements, the CGX is an excellent performer in the field regarding guiding accuracy, which is sure to make your images look excellent without streaking. Thanks to the easy computer connectivity, you can slew around with ease without ever even having to use the hand controller.
Users of the CGX can expect sub-arcsecond guiding with appropriate payloads and guiding setups. You can easily use an 8-9.25” SCT/reducer, 11” RASA, 6” refractor, or 10” Newtonian on the CGX for long-exposure imaging. A 10-11” SCT can also work if you don’t push exposure times too long.
Should I buy a Used Celestron CGX?
The CGX is a fairly new product, so you might have trouble finding a used one that’s in working order. However, if you can do so, there’s no reason not to buy a used CGX. Replacing missing counterweights or the hand controller is fairly trivial.
The CGX is one of our top picks for an equatorial mount. However, here are a few other mounts which you may want to consider:
- The Sky-Watcher AZ-EQ6i is smaller and has slightly less capacity than the CGX but features stepper/belt drives and a USB-B port, along with a retractable counterweight shaft, the ability to be used in alt-azimuth mode with two telescopes and Sky-Watcher’s FreedomFind technology to allow for manual aiming.
- The Sky-Watcher EQ6Ri Pro is similar to the AZ-EQ6i but lacks a USB-B port, FreedomFind technology or an alt-azimuth configuration.
- The Losmandy G11 Gemini II has similar weight capacity to the CGX, though it’s not nearly as technologically well-equipped.
Aftermarket Accessory Recommendations
The CGX needs a polar scope or PoleMaster for polar alignment. The former awkwardly attaches to the side of the CGX and will crash into your telescope or the mount’s declination axis if you don’t remove it after polar alignment. A PoleMaster is a superior solution, though you can get away with using the CGX’s All-Star Polar Align too. A battery such as the Celestron PowerTank Lithium Pro is also essential for running the CGX in lieu of an AC adapter.