Balance is what lets a small motor move a heavy tube

The best counterweights for 2026

A counterweight balances an equatorial mount so that the tube stays where it is put with the clutches loose, and so that the drive motor turns a load that is nearly weightless instead of dragging one that is not. Balance is not a refinement here — an unbalanced mount tracks badly, backlash shows in one direction and not the other, and the gears wear. The specifications are few and unforgiving. The bore diameter must match the counterweight shaft of the mount exactly; shafts come in several diameters and a weight that does not slide on is not adaptable. The mass has to be considered together with the length of the shaft, because torque is mass multiplied by distance: a heavier weight close to the mount and a lighter one far out can balance the same tube, and the lighter arrangement puts less total load on the bearings while the heavier one keeps the center of gravity compact. Most owners end up with two weights rather than one, which allows fine adjustment by moving the smaller one. Read the locking method: a knob that bears directly on the shaft marks it over time, while a collar or a brass insert spreads the load. Read whether a safety collar or a retaining bolt is fitted at the end of the shaft, since a weight that slides off is the most predictable accident in the hobby. Coating matters for a part that lives outdoors. We compare mass, bore diameter, locking method, coating and finish, compatible mounts and overall dimensions.

By Jean-Benoit Buisson