iOptron CEM40 Center-Balanced GoTo Equatorial Mount with iGuider, iPolar, LiteRoc Tripod, and Case – C402AG3
With its center-balanced design, precision tracking, and lightweight portability, the iOptron CEM40 sets a new standard for mid-capacity equatorial mounts. This feature-rich version—part number C402AG3—includes iPolar electronic polar alignment, the fully integrated iGuider autoguiding system, the rugged LiteRoc 1.75” stainless steel tripod, and a custom-fit hard case to protect your investment. Whether you're a deep-sky imager, eclipse chaser, or serious visual observer, the CEM40 is engineered to go where you go—and perform when it gets there.
The Power of Center Balance
At the core of the CEM40 is iOptron’s patented Center-Balanced Equatorial Mount (CEM) design. Unlike traditional German equatorial mounts, the CEM places the center of gravity directly over the tripod, reducing torque and increasing stability—particularly under heavier payloads.
Despite weighing just 15.8 pounds (7.2 kg), the CEM40 supports up to 40 pounds (18.1 kg) of equipment. That’s more than double its own weight, giving it one of the best payload-to-weight ratios of any mount in its class. This makes the CEM40 ideal for everything from large refractors to imaging rigs with heavy cameras, filter wheels, and accessories.
Built-In iPolar: Fast, Foolproof Alignment
Polar alignment is critical for accurate tracking and autoguiding, and the iPolar electronic polar scope included with the CEM40 makes the process fast and foolproof. Whether Polaris is visible or not, iPolar gives you a digital alignment interface to match the sky—even in light-polluted or obstructed locations. No more crouching behind a reticle eyepiece or struggling with drift alignment.
Integrated iGuider Autoguiding System
Included in this package is the iOptron iGuider system, seamlessly built into the RA axis of the CEM40. This all-in-one autoguider includes:
It’s optimized for short to mid-focal length setups and delivers precise guiding performance without extra cabling or mounting rings. It’s plug-and-play, clean, and tailor-made for portable imagers.
Precision Engineering and Motion Control
The CEM40’s precision stepper motors offer microstepping accuracy and ultra-low power consumption. Combined with iOptron’s quiet belt drive transmission, the result is smooth, silent motion with nearly imperceptible backlash. Tracking and slewing are fluid and reliable, whether you're moving at sidereal rate or jumping 4° per second to a new target.
Tracking features include:
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Permanent Periodic Error Correction (PPEC) to flatten RA error over time
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User-adjustable backlash compensation
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ST-4 compatible autoguider port for external guiding if desired
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Guiding and centering speeds from 2x to 128x sidereal
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Slewing speeds up to 4°/second
GoToNova® Control with Massive Database
The Go2Nova® 8407+ hand controller gives you fingertip access to over 359,000 celestial objects. The controller includes a high-contrast, heated LCD display for visibility in cold temperatures, and backlit keys for operation in the dark.
The mount’s GoTo capabilities include:
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Object catalogs: Messier, NGC, IC, UGC, Abell, Herschel, and more
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Named stars, double stars, variable stars, comets, asteroids
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Automatic tracking and slewing
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Real-time position and object ID functions
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Support for user-defined targets
Cable Management and Mounting Flexibility
The CEM40's internal cable management system helps eliminate tangled wires and reduces the risk of snags while slewing. The Universal Self-Centering Saddle (USCS) accepts both Vixen and Losmandy-style dovetail plates, automatically centering the load for better balance and safety.
GPS and Connectivity
This version includes an integrated 32-channel GPS receiver for automatic time and location sync—no more manual entry or waiting for satellites. The CEM40 is also equipped for modern connectivity, including:
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USB port for PC control (ASCOM/INDI-compatible)
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RS232 communication
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Optional external Wi-Fi module
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Firmware upgradeable via USB
LiteRoc Tripod and Case Included
The included LiteRoc tripod features 1.75” stainless steel legs with adjustable height and a die-cast spreader tray. It offers the rigidity needed for heavy loads while remaining manageable in the field at 15 pounds (6.8 kg).
To top it off, iOptron includes a fitted hard case for the CEM40 mount head—an essential upgrade that protects your gear during transport or storage.
Observing Tip:
The center-balanced design of the CEM40 means it’s far less sensitive to imbalances than a traditional GEM. Still, take the time to balance your RA and DEC axes precisely—especially when using heavier imaging gear. A well-balanced system reduces motor strain, improves tracking accuracy, and extends battery life in the field.
Final Thoughts
The iOptron CEM40 C402AG3 package delivers a rare combination of strength, precision, and portability. With the iPolar polar scope, integrated iGuider, full GPS, and onboard GoTo database, this mount is ready for serious imaging right out of the box. Whether you’re building a mobile rig for dark sky adventures or setting up a semi-permanent observatory at home, the CEM40 offers professional-grade features in a compact, intelligent package.
