Thanks Paul,
Collimation I don't think is the issue , as their were brief moments of great clarity in the feed.
Cooling though could be an issue (mainly as I have none!
) (Future project
). To describe the effect, it was as though someone was racking in and out of focus (mostly out), very little of the jelly wobbles. I could be wrong but I have been told, and it seems logical, that the in/out of focus effect is a result of higher/fast moving inhomogeneities in the air, whilst the wobbles are likely to be local effects.
I expect that the thin layer of warmer air adjacent to the mirror as the system cools, which you SCTers and similar closed tube system address with active cooling would result in a system that appeared to lack good collimation, frustrating attempts to achieve as good a focus as you know the system is capable of. And of course the tube currents are a bit easier to diagnose.
I have a Newtonian system (as I'm sure you know) and have long thought about cooling. Perhaps as you say, the time has come to try
My initial thought was to mount a simple fan on the rear as a first step, but I am happy to consider other arrangements.
