iOptron CEM26 EQ Mount Review: Recommended Mount

Mechanics

The iOptron CEM26 consists of a compact mount head that can rotate on two axes, and a sturdy stainless steel tripod with adjustable legs and a built-in bubble level. The mount head has a saddle plate that can accommodate either a Vixen or a Losmandy style dovetail bar, allowing it to hold a variety of telescopes or cameras. The mount head also has a built-in carry handle and a snap-in battery pack that can power the mount for up to 10 hours.

The CEM26 uses a unique center-balanced design that places the center of mass over the tripod, reducing the torque needed for either and increasing the stability of the mount. This means that the mount can support up to 26 pounds of payload (iOptron claims up to 33 lbs if you switch to the LiteRoc tripod or a pier, but we wouldn’t try it). This also means that the mount does not need as many counterweights to balance the load, saving weight and space. The design also has the declination shaft away from the polar scope, meaning the polar scope is never obstructed by the declination axis. iOptron supplies a single 10 lb (4.5 kg) counterweight with the CEM26, and for imaging use it is likely all you need, though the shaft’s 20mm standard diameter means it accepts most counterweights made for other mounts in addition to the ones iOptron sells.

The CEM26 uses a belt-driven dual-axis stepper motor system that provides smooth and quiet operation with low backlash and low periodic error. The mount can track at four different speeds (solar, lunar, sidereal, or custom), and can slew at up to 6 degrees per second. The mount also has a built-in dual encoder system that ensures the mount does not lose its alignment even if it is accidentally bumped or moved. The dual encoders also allow you to manually aim the CEM26 without affecting the accuracy of its tracking or star alignment.

The CEM26 is lighter than most similar mounts in its class, with the mount head weighing only 10 lbs. and the LiteRoc tripod weighing 11 lbs. The LiteRoc tripod is made of aluminum and has legs that can be adjusted and a bubble level that is built-in. It provides some stability for the mount and the load, but for heavier or larger setups, it may be too wobbly. The tripod also has a tray for storing the hand controller or other accessories. The iOptron TriPier can also be used with the CEM26 for more robustness and stability.

The CEM26 has a basic Vixen-style dovetail saddle, which we would highly recommend you replace with an aftermarket dual Losmandy/Vixen saddle from ADM so you can use either size dovetail plate and have a more solid connection with your telescooe’s dovetail bar. The stock saddle has no safety mechanism and clamps to your dovetail with a single knob. The clamping system won’t mar your dovetail with bit marks, but it is bad to rely on a single point of failure for attaching your optical tube and astrophotography gear, especially when said kit can cost more than a nice car.

Balancing a telescope on the CEM26 is a little different from what you might be used to with a regular German equatorial mount. Your scope and the declination axis are to the rear of the counterweight, so it might take a bit to sort out how much counterweight you need for the RA axis and where your optical tube/rings need to be to balance on the declination axis. However, once you’re used to this, you’ll practically forget there is anything at all out of the ordinary with the CEM26 compared to any other mount.

Electronics

The iOptron CEM26 features a GoTo system that can automatically point to over 200,000 objects in the sky, such as planets, stars, nebulae, galaxies, and more. The mount also has a built-in GPS and WiFi module that can provide accurate time, location, and alignment data. 

The CEM26 comes with the iOptron Go2Nova hand controller. This controller has various settings for speed, backlash compensation, and, of course, how you align and point the mount in the night sky. However, like all hand controllers, it’s far from intuitive or convenient to use, and as such, you might want to take advantage of the CEM26’s inbuilt WiFi module or USB port and operate it via your smartphone, tablet, or PC instead. You can use the official iOptron Commander, which can be downloaded for free from the App Store or Google Play. The app can connect to the mount via WiFi and provide a graphical interface for controlling the mount and selecting objects, as well as assist in polar alignment. While not free and not able to help with doing a software polar alignment, SkySafari Pro is a lot more intuitive than the Commander app and will also work to remotely control the CEM26.

A PC can also be used to control the CEM26 mount via ASCOM drivers that can be downloaded from the iOptron website. The PC can be connected to the mount via a serial cable or wirelessly, with the mount’s WiFi adapter. A PC can provide more options and features for controlling the mount and interfacing with other software, such as planetarium programs, imaging software, or autoguiding software.

The CEM26 mount also has an autoguider port that can accept a standard ST-4 cable from an autoguiding camera or device. An autoguider is a must-have for any mount, including the CEM26, as it will help with correcting the inevitable tracking errors or drifts of the mount during long-exposure astrophotography before they build up and ruin your images.

Like the GEM28 and other iOptron mounts, the CEM26 is available in a number of variants – as well as the different tripod options, iOptron offers the CEM26EC, an enhanced version with better drives and a built-in set of tools, namely iOptron’s iPolar electronic polar alignment tool as the 

Using the iOptron CEM26 for Visual Observation

The iOptron CEM26 is a versatile and convenient mount for visual observation with a variety of telescopes. To use the mount for visual observation, you will need to attach a telescope to the mount with a dovetail bar. You will also need to level the mount, conduct a rough polar alignment, and align the mount on the sky with your control method of choice (Go2Nova controller, app, or PC). If you’re using the controller or a smartphone/tablet, GPS data will automatically update the date, time, and location of the mount thanks to its onboard sensors. Once alignment is complete, the CEM26 mount will then automatically slew to and track objects. 

The CEM26 is reasonably user-friendly to operate via the Go2Nova controller or with your smart device, and of course you can always unlock the clutches and aim the mount manually thanks to its built-in encoders. The mount can track at sidereal, lunar, or solar speeds, depending on the object you are observing. The mount can also track at custom rates, which can be useful for observing objects that have different apparent motions, such as comets, asteroids, or satellites.

The CEM26 is rated to hold up to 28 lbs., or 33 lbs. with the LiteRoc or another sturdier tripod. However, in practice, 20-25 lbs is the realistic limit of this mount’s capacity, and even then only for non-critical applications like visual observing. This corresponds to a 9.25” Cassegrain, 6-8” reflector, or 6” refractor. Overloading the mount above this limit is going to lead to vibration issues long before it actually becomes too heavy for the mount itself to function.

Astrophotography

The iOptron CEM26 is a capable and user-friendly mount for astrophotography with a camera and a lens or a small to medium-sized telescope. You can control the mount the same way you would for visual observing (i.e., via your phone or the Go2Nova hand controller), but we would recommend plugging it into a PC.

The CEM26 can hold up to about 15-20 lbs for astrophotography purposes (the rule of thumb being that a mount can hold ⅓ to ⅔ of its weight rating for astrophotography). This corresponds to an 8” SCT or Ritchey-Chretien, 4” refractor, or 8” Newtonian reflector. Larger telescopes will be unsteady and induce tracking errors in the mount. If you’re finding yourself needing an additional counterweight for the CEM26 to supplement the provided 10 lb one, stop – your rig is getting too heavy for this mount, with or without the LiteRoc tripod or a pier.

With a sufficiently low payload, autoguiding (a must for good images), and accurate polar alignment, the CEM26 tracks extremely well thanks to its stepper-driven belt drives, which should guide at well under 1 arc second in most situations.

Like most quality German equatorial mounts, the CEM26 is compatible with ASCOM drivers, and while you could use the hand controller or a smartphone/tablet app to control it for imaging, the best option is usually via a PC connected to the mount’s USB port or connected over WiFi. With a PC and automated image sequencing software, you can control your guiding, where your mount is pointed, automatically plate solve to find and center a target, and make adjustments to your motor focuser and filter wheel if you have one. If you’re operating the CEM26 in this manner, there is no need to perform a star alignment with an app or hand controller – just assemble, polar align, and let the software take care of the rest.

Should I buy a Used iOptron CEM26 mount?

The iOptron CEM26 is a relatively new product and may not be widely available on the used market. However, if you can find a used CEM26 in good condition at a reasonable price, it may be worth considering. The good news is that this mount is fairly durable, with few plastic parts, and its slip clutches and other mechanical components are unlikely to degrade or fail easily. However, you should check the condition and functionality of the mount before buying it if possible, and make sure that the battery still works. If the mount is missing any accessories or cables, or if they are damaged or faulty, you may need to purchase them separately, which can add to the cost.

Alternative Recommendations

The iOptron CEM26 is a compact and lightweight equatorial mount that offers convenience, portability, and performance for amateur astronomers and astrophotographers. However, it may not suit everyone’s needs and preferences, and there are some other options within its price range that merit consideration.

Under $1500 USD

• The Sky-Watcher HEQ5i Pro (also sold as the Orion Sirius EQ-G) is a classic and reliable German equatorial mount that can be used for both visual observation and astrophotography with small to medium-sized telescopes or cameras, up to 25 lbs or 15 lbs for visual/imaging respectively. The HEQ5i Pro is similar in features, specs, and performance to the CEM26, but its interface is a bit simpler, more aftermarket accessories are available, and it features a sturdier 1.75” steel tripod by default.
• The iOptron GEM28 is essentially a CEM26 without the center-balanced configuration, with similar performance, specs, price, and features, as well as the same component/accessory configuration options.
• The Celestron Advanced VX is an affordable and proven equatorial mount, with a beefy 2” steel tripod and up to ~30 lbs weight capacity for non-critical applications. The Advanced VX is considerably inferior to the HEQ5i and CEM26, however, lacking WiFi operability by default, requiring the use of the hand controller to connect to a PC, and depending on low-quality servo motors for slewing/tracking.
• The Sky-Watcher EQM-35i Pro is a budget equatorial mount from Sky-Watcher, featuring a similar frame to the HEQ5i Pro and only slightly lowered weight capacity, along with quality, quiet, high-resolution stepper motors and the option of either a WiFi dongle (default) or SynScan V5 hand controller for operation.

$1500-$2500

• The Sky-Watcher EQ6Ri Pro is a robust German equatorial mount that can be used for both visual observation and astrophotography with large telescopes. has a payload capacity of 44 pounds, making it suitable for large refractors, catadioptrics, or reflectors. It also features a GoTo system with a built-in database of over 42,000 objects, and like other Sky-Watcher mounts, it is available either with a WiFi dongle (controlled via the SynScan Pro app) or a SynScan V5 hand controller with a backlit LCD screen. The EQ6RI also features a built-in polar scope, and a belt drive system that reduces backlash and periodic error.
• The Sky-Watcher AZ-EQ6i, essentially an upgraded EQ6Ri Pro, has all of the EQ6Ri’s features with the added bonuses of Sky-Watcher FreedomFind encoders (allowing you to aim the mount manually by unlocking the clutches as in the CEM26), and the ability to be used in alt-azimuth mode. In its alt-azimuth configuration, the AZ-EQ6i can also hold a second, smaller telescope on the end of the mount’s counterweight shaft.
• The Sky-Watcher AZ-EQ5i, like the AZ-EQ6i, is a hybrid mount that can be used as either an alt-azimuth mount or an equatorial mount, depending on the user’s preference and purpose. It can be used for both visual observation and astrophotography with medium-sized telescopes or cameras, and features a similar weight capacity rating to the HEQ5/HEQ5i Pro. The AZ-EQ5i also has a dual encoder system (Sky-Watcher FreedomFind) that allows manual pointing without losing alignment.
• The Orion Atlas EQ-G (also known as the Sky-Watcher NEQ6) is a predecessor to the EQ6Ri, with many of the same features but no belt drives and usually controlled by a SynScan V5 controller.
• The Celestron CGEM II is similar to the Advanced VX but features a beefier mount head similar to the EQ6Ri or Orion Atlas. However, it lacks these mounts’ software compatibility, stepper motors, or even a polar scope provided by default, making it only really useful for non-imaging applications.

Aftermarket Accessory Recommendations

Besides a guide camera/scope which are essential for using the CEM26 for astrophotography with any telescope, you may also want to invest in the iOptron iPolar for your CEM26. This tool is similar to the QHY PoleMaster and dramatically speeds up polar alignment if you’re unfamiliar with the process. As mentioned earlier, ADM’s dual saddle for iOptron’s CEM26 mount is a must, both for its more solid connection with your telescope’s dovetail bar and also for the Losmandy D-style dovetail plate compatibility it offers.

Of course, you’ll also need a power supply for the CEM26, such as the Celestron PowerTank Lithium or a generic equivalent such as from Westinghouse.