Unbalanced Scope

[TrickySpot]

Hi Guys,

I have just piggybacked a Megrez 72 on the back of my Equinox 100, and have a red dot finder on the Megrez. When I try and balance in the DEC axis, it balances on one side, but is front heavy on the other. The only thing I can think of is that the bolts for the tube rings and the red dot finder are all on one side......how do people usually fix this, is it a case or remounting the rings the other way round??

Thanks for the help!

[Dann]

If your balancing the dec axis by either sliding your OTA in the rings or moving the dovetail in the mount you could also try rotating the OTA in the rings.

I personally dont do that as I always end up rotating the tube during the night to achieve a better eyepiece position anyway, although I have seen video tutorials that suggest doing it.

[Ad Astra]

With finder scopes that weigh more than a few grams, there is really no way to mount them and still maintain 'perfect' balance. Think of it this way - your scope's long axis (the optical axis) represents the center of mass - when you mount a finder or guide scope, it MUST be 'off axis'. This means that as the scope rotates on ANY axis, the off-center weight will cause some balance issues.

Generally, you can position the scope to minimize this, but not totally eliminate it. Setting the Dec and RA locks to minimum friction will eliminate the problem, and many GEM mounts will advocate a slight imbalance, meaning that the drive motor has a load to work against - this is so that the drive motors and gears will stay meshed properly. If a scope is truly in "perfect" balance, the play in the drive train can cause the scope to 'bounce' as the drive motor moves. Nothing you would notice visually, but it can play merry hell with imaging and cause you no end of headaches.

The short answer is that a slight imbalance should not be a problem. Do the best you can and then relax and enjoy the views!

I hope that helps a bit,

Dan