Question Linear: how important is balance?

Hello,

I have a Linear HD with a 106mm apo, 60mm guide scope, 0,75 reducer/flattener, ZWO EAF, ZWO 36mm EFW and ZWO 2600MM Pro. Linear is more than enough to carry the weight, but what about balance? EAF is on one side and EFW is being routinely rotated to correctly frame deep sky objects. So, EFW and one single (pretty heavy) power cable from a Pegasus micro hub contribute to shifting center of gravity.

it is pretty impossible to achieve perfect balance on both sides of the mount and I strongly suspect that an imbalance is the cause of frequent spikes in guiding. Last time out, the mount was balanced for imaging in the eastern side of the sky. Seeing was pretty good, average RMS was around 0,4” but with occasional spikes up to 2,5 - 3”. In R.A., DEC or both. No pattern. After meridian flip guiding got much worse, while seeing was apparently the same. I am using PHD2 with NINA. I tried recommended settings and have also experimented a bit, but to no avail. 

so, how important is the balance? How to balance everything with off-center EAF and EFW? Should I re-balance the scope after meridian flip? How do you deal with balance?

Comments, suggestions welcome…

Thank you!
Jure

Hello Stefano,

If I balance the telescope perfectly in the area I want to image, let’s say Vulpecula, mount is on the eastern side, facing southward, then:
- if I move the telescope in DEC axis only to the northern side, it will be heavier in front.
- if I move the telescope to the western side, telescope facing north, it will be heavier on the back and if I move it to the southern side only DEC axis, it will be heavier in front. Also, usually R.A. is not perfectly balanced anymore.

Movement is not violent, the telescope finds the equilibrium at some point, it won't hit the tripod.

So, if the balance is not “guilty” for spikes in guiding, could it be seeing? It is usually not great at my site, but could such sudden turbulence in the air mass cause 2” - 3” spikes in guiding?

Thank you for responding! 

Jure