iOptron HEM27 or HEM44 Counterweight Bar

iOptron Counterweight Bar for HEM27, HEM44, CEM26, and GEM28 Mounts

iOptron Part Number: 8456SL

Need just a little more stability when your imaging payload pushes the edge of your mount’s capacity? The iOptron 8456SL counterweight bar gives your lightweight strain wave mount the added balancing leverage it needs—without overcomplicating your setup.

Originally designed for the CEM26 and GEM28, this 20mm steel counterweight shaft is also fully compatible with the HEM27 and HEM44 mounts. It threads directly into the base of the mount, letting you use iOptron’s standard 20mm bore counterweights to improve balance, reduce stress on the motors, and increase tracking accuracy under heavier loads.

Why Add a Counterweight Bar?

One of the major selling points of the HEM series is their ability to run without counterweights. But as your setup grows—perhaps with a larger OTA, filter wheel, motorized focuser, or heavier guide scope—things can get a little unbalanced. Over time, that can impact tracking accuracy and even reduce mechanical longevity.

Adding this counterweight bar lets you shift the center of mass back over the mount’s axis and ensures your strain wave drive performs at its best. It also gives you more precise control when balancing heavier rigs in declination.

This is especially helpful when:

• You're using long refractors (4" or larger)

• You’ve added a full astrophotography setup with multiple accessories

• You’re guiding with an off-axis guider or dual imaging system

• You want better low-latitude performance and tripod clearance

Compatible Mounts

• HEM27

• HEM44

• CEM26 (original factory counterweight bar)

• GEM28 (original factory counterweight bar)

The bar accepts 20mm bore counterweights, including those sold for the GEM28, CEM26, and other compatible iOptron mounts.

Specifications

• Material: Stainless steel

• Bar Diameter: 20mm

• Bar Length (not including threads): 200mm

• Total Length (including thread and safety screw): 224mm

• Thread Size: M16 x 2mm (both ends)

• Includes: Safety locking screw to prevent slippage

Observing Tip

Even if your HEM mount seems to handle your scope just fine without a counterweight, you might notice improved guiding performance when you add one—especially at higher magnifications or when imaging under gusty conditions. A small counterweight can make a big difference in keeping motor torque steady and motion smooth.

Why Choose the 8456SL Counterweight Bar?

Lightweight mounts are a revelation for portability, but balance still matters when precision tracking is on the line. This compact counterweight bar brings additional versatility to your HEM27 or HEM44, giving you the option to fine-tune balance when your setup outgrows counterweight-free mode.

Whether you're prepping for a heavier OTA or planning to swap scopes often, this is an inexpensive upgrade that can significantly improve long-term performance.