Why do we balance a telescope in right ascension (R.A.) or in declination (dec.)?

Question

Obviously the scope needs to be balanced so that it moves freely (on the German equatorial [G.E.] mount) about both the R.A. and dec. axis (pl. form?), but I don't know much more than that. My instructional manual talks about how to balance the reflecting telescope in R.A. and in dec. (though I could use a little clarification on their instructions) but it does NOT explain why you would put the telescope in either of these positions. I understand that R.A. involves moving the scope around the polar axis, and declination allows you move away from the center of the sky's rotation (practically centered on Polaris) to any star in the sky, except when the tripod gets in the way. How do we balance the scope in each position, and why do we choose one over the other?

Bonus question: With a smaller weight and a larger weight, how are each used in the balancing process and is it okay to switch the weights with the scope still attached to the mount?

Answer 1

You need to balance the scope so it will move smoothly. Otherwise, it becomes very difficult to position the telescope. If you have motor drives, they typically don't have enough torque to move the scope properly if it's unbalanced. I'm not sure what positions you're talking about. but they may just be convenient positions to check the balance of each axis independently.

You will find that aiming a GEM-mounted scope involves some odd contortions. For example, when moving across the meridian (south point) you have to spin both axes 180° to avoid interference. Some mounts are more tolerant than others, but all of them eventually run into trouble if you let the counterweight shaft get higher than the telescope tube.

Generally, you need counterweights equivalent to about 75% of the weight of your telescope and its attachments. The further out on the shaft the weight is, the more weight it can counterbalance, though it's a little more stable with the weights closer in. So it generally works out best to put the small weight on first and have the large weight closer to the end of the shaft. Removing the counterweights with the scope attached can be dangerous - the unbalanced weight may be enough to break free of the axis lock and let the scope crash into the tripod. In some cases, you might also overbalance the tripod and tip the whole thing over. Best to make that a two-person job, with one of you holding the telescope.

Answer 2

your scope needs to be balanced so that it can track properly. in one axis you have to make sure the scope is evenly distributed. this means lossening the clamps that hold it to the scope so you can move it forward or backwards to balance it. after this is accomplished, then you need to use counterweights to counteract the weight of your scope and camera if you are using one. just check your manual to see how much your optical tube assembly weighs and counter it with a weight of similar weight, slide it up and down the bar until you get the proper balance. i hope this is understandable and that it helped you!!!!!