Balancing an Equatorial Mount

Balancing the Mount

The next step in the setup of your equatorial mount is to balance it in the two dimensions corresponding to the two axes of movement.

Note: This article used to recommend doing the two steps below in the other order, but reader Steven Yokey kindly referred me to a good article explaining why it is better to do the Declination axis first. I’ve reversed the order, so the steps below now reflect the advice in that other article. Thanks Steven.

Why Balance?

Balancing your mount is an important step (often overlooked by beginners). A balanced scope will move more smoothly and will tend to stay where it is put until you move it, while an unbalanced scope will have jerky motions, be unstable, and tend to drift. Worse, an unbalanced scope puts more load on the gearing in the slow-motion controls, and can cause the small motors in a motorized scope to overload and burn out.

Getting Ready

Complete the assembly of your mount, including the counterweights and attaching the telescope.
Load up the telescope with all the accessories you are likely to be using in tonight’s observing session: the finder, dew shield, diagonal, and an average-sized eyepiece. Include the camera if you will be doing photography. The idea is to put the amount of weight on the mount that you will be using for the evening.

Balance in Declination

First, we’ll balance the scope on the declination axis, which is the motion around the counterweight shaft.
Loosen the clutch that stops the mount from moving on the Right Ascension axis and turn this axis so that the scope is sticking out to one side of the mount, roughly level with the counterweight at the other side. This gives room to allow the optical tube to rotate on the Declinaion axis. Tighten the RA clutch so the scope stays in this spot..
Holding the scope in one hand to prevent it from crashing into the mount, use the other hand to loosen the clutch allowing motion on the Declination axis.
The scope will probably flop to one side or the other, as it is probably not balanced.
Adjust the balance by moving the scope forward and backward – either by loosening the mounting rings and sliding the tube back and forth in the rings, by sliding the dovetail back and forth in the mounting plate, or whatever other means your mount has of moving the balance in this direction.

In some rare cases – usually involving a light telescope connected to a heavy camera – you may not be able to slide the OTA or dovetail far enough to reach balance. In such cases you may need to buy or build some kind of counterweight that fits onto the OTA or dovetail (usually the dovetail, near the front) to help achieve balance.

In the above photos no such “declination counterweight” is needed.In the photo to the right, as an example, a home-made counterweight (a hunk of brass) is bolted on to the underside of a lightweight OTA, near the front, to offset the weight of a heavy camera on the back.

Continue adjusting until the scope balances in Declination without being supported. Then tighten the Declination clutch again.

Balance in Right Ascension

Next, we will balance the mount around the Right Ascension axis.
Holding the telescope with one hand, loosen the clutch that stops the mount from moving on the Right Ascension axis enough so that it can move freely.
Carefully let the scope flop to the side, which will happen because the scope is putting weight on its end of the RA axis. Don’t let it free-fall! Help it down gently with your hands.
Loosen the clamp holding the counterweight and slide it back along the counterweight shaft, then check the balance again.

Continue adjusting the counterweight until the scope will balance evenly on this axis.

Small mounts will come with a small counterweight suitable for a small telescope (or with the supplied telescope if purchased as a kit). If you change to a larger telescope, or add a camera or heavy accessories, you will almost certainly need another or a larger counterweight.

Return the scope to its normal upright position, and tighten the Right Ascension clutch so it stays there.


Congratulations, you have now balanced your telescope in both dimensions of motion. You can loosen the clutches and return the scope to its normal rest position. When you later move the scope to find or track objects, it will be well balanced and smooth and, if you have electric drive motors, you will have minimized the work they have to do.

The next step is to adjust the Finder.


  1. I have the skywatcher EQ6-Rpro. Rated at 44 pounds of payload. My telescope is 152mm lens and 1200mm focal length. The telescope with rings, finder and eyepiece weighs approximately 25 pounds. The mount has two 11pound counterweights. I used to have a AVX advanced mount and I balanced perfectly with my OTA But with this much bigger the EQ6-rpro I can perfectly balance in both axis but when I put the telescope in the home position the tube drifts to the left. It’s balanced in the pics shown here but still drifts to the left in the home position. Very frustrating. On the much lighter AVX mount it does not drift like that but when I balance on the bigger mount the tube drifts slowly to the left.

  2. Dano, A mount is rated for payload. The counter-weights are not part of the mount’s payload. What is on the other end of the counterweight shaft is the payload.
    Jon, Ideally, you want the weights to be as close to the payload as possible. In any event, you do not want the weights to ever touch the tripod (or anything else). A large diameter weight could be a bad idea.
    For astro-photography, most old timers say to keep payload no more than 65% of rated payload. So, this makes getting a bigger mount something to consider. For visual work this rule of thumb is not that important.

  3. If your mount is rated at 30lbs should you keep the counterweights under 30lbs. If my load is only 24lbs why can’t I balance it with less then 30lbs of counterweight. I use 33lbs of counterweights to balance, Why?

    1. It has to do with the distance from the center of gravity of the counterweights (c/w) to the tube assembly. Plus it depends on the diameter of your counterweight. If you had a bigger diameter counterweight, you probably would not need so much c/w. For instance, if you have six 6 pound c/w, they would be in a row, and the center of gravity of them would be in the middle of the six. If you had one 30 pound c/w, the center of gravity would be in the middle of it, putting it closer to the center of gravity of the axis. so a bigger diameter c/w would allow you to use less weight, because you could put it closer.

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