[QUOTE=marc4darkskies;1055591 My theory is that this is more a vibration set up when starting and then stopping (via a guide correction) a large mass. The measures I've taken support this theory - adjusting the spring plungers (small effect), reducing aggressiveness and increasing guide period. I suspect now, if I'm right, that correct guide rate + aggressiveness settings will solve the problem. However, I won't do any more testing until I've got my collimation sorted out.[/QUOTE]
Hi Marcus,
By your own post earlier, you don't actually start or stop the mount in RA when guiding unless the guiding rate is set above 1, which would be silly to do, the mount slows down or speeds up only, so this should not cause oscillation. Don't forget to do the calculations to work out you minimum guide correction, depends on your image scale, it's something many people have set way to small.
http://www.ccdware.com/resources/autoguidercalcv4.cfm
Cheers
Stuart