iOptron 21 lb Counterweight for iEQ45, CEM60, GEM45, and CEM70 Mounts
Part Number: 7226
Heavy Duty Balance for Heavy Duty Payloads
As your imaging train grows—larger OTAs, full-frame cooled cameras, filter wheels, guide scopes, dew heaters—the need for precise, reliable counterweighting becomes more than just a mechanical concern. It's the key to smooth tracking, reduced motor stress, and razor-sharp exposures.
The iOptron 21 lb (9.5 kg) counterweight is designed for astronomers who are pushing their mounts to full payload capacity or using large optical systems that require more than the standard 11 lb or 5.5 lb weights. Whether you’re balancing a heavy imaging rig or looking to reduce the number of weights stacked on your shaft, this single 21 lb solution simplifies the loadout while increasing stability.
Made for iOptron’s Most Capable Mounts
This counterweight is machined to fit 29mm diameter counterweight shafts, which are found on iOptron's higher-capacity mounts. It includes a built-in locking hand knob for easy field adjustments and features a compression-ring clamp with a brass-tipped screw, which grips securely without damaging the shaft finish.
The weight is finished in matte black, with a footprint of approximately 6" in diameter and 3" in height. It’s compact enough to stack with other weights if needed, but in many cases, a single 21 lb weight is all you'll need to balance medium-to-heavy payloads.
Compatible Mounts
This 21 lb counterweight fits any iOptron mount with a 29mm counterweight shaft, including:
⚠️ Compatibility Note: Some early-production CEM40 and GEM45 models used 20mm or 28mm shafts. Be sure to verify your counterweight shaft diameter before ordering this 29mm version.
Technical Specifications
| Feature |
Specification |
| Weight |
21 lbs (9.5 kg) |
| Fits Shaft Diameter |
29mm |
| Material |
Cast metal with matte black finish |
| Clamp Type |
Brass-tipped screw with compression ring |
| Diameter |
Approx. 6" (152mm) |
| Height |
Approx. 3" (76mm) |
| Attachment |
Hand knob for tool-free field adjustments |
| Compatibility |
CEM70, GEM45*, CEM60, CEM40*, iEQ45 Pro |
Observing Tip
Instead of stacking multiple smaller weights—especially when working with long focal length OTAs or off-axis guide setups—a single 21 lb weight can help lower your system’s center of gravity and reduce the load on the far end of the counterweight shaft. This makes balancing quicker and more precise, and minimizes potential vibration or shaft flex during tracking and slewing.
Final Thoughts
The iOptron 21 lb Counterweight (#7226) is the go-to solution for astronomers running high-capacity systems on CEM70s, CEM60s, and other full-size equatorial mounts. It offers serious counterbalancing power in a clean, compact form. If you’re building a rig to reach the upper limits of your mount’s rated payload, this weight will help you do it right.
