Autoguiding catch me out.

[JohnG (John)]

Hi all

Thought I would pass this on.

Over the last few weeks I have been getting some tracking errors on my autoguider setup (ED80 on a TGAD with ST-4). Stars have suddenly starting to appear out of round with the occassional streaks.

This all started happening about 3 weeks ago. At that time I replaced the standard finder with a right angle finder which was slightly heavier.

Yesterday while doing some essential maintenance on my mount and gear I noticed out of the corner of my eye the guidescope moving ever so slowly.

It has turned out that the guidescope was rotating within the tube rings even though they were tight, it appears that the extra weight of the finder caused this slow turn thus throwing the ST-4 out and causing it to give ever increasing corrections.

I have fixed the problem by placing some thin rubber strips inside the tube rings and filing off where they join.

Another live and learn guiding experience.

Cheers

JohnG

[RB (Andrew)]

Thanks for the info John.
Such a fine line to walk in this hobby of ours to achieve perfection.

Glad you found the problem.

[Striker (Tony)]

It doesn't take much John,

Even flex between dovetails and rings can cause the same problem.

Rock solid with everything is the only way.

[JohnG (John)]

Yeah, it was interesting, it was the tube actually rotating on the felt that was the problem. Just that slight increase in weight caused this.

Cheers

JohnG