Thanks all. My goal is to push my gear and processing to its limits and I have been very pleased with the results I have been seeing recently, especially with the benefit of longer (dare I say "mega") integration. However I don't mean in any way to imply that my images are perfect (far from it) and completely agree that the star shapes are "unusual" here. In fact I am very much open to suggestions as to what the cause may be - all the subs have these odd shapes.
As a start I will check the collimation over the weekend with my cats eye gear, and also check the primary mirror clips in case it is pinching. I also have a tilt adapter I can use if need be. Pinching/distortion of the secondary is also a possibility I have considered. The secondary is a GSO 50mm from my dob, and is glued into a recessed secondary holder so it will be difficult to pry loose without damaging it. In any case I will report back on the progress for the benefit of others who may refer to this thread at a later date.
It can be a slow going to trouble shoot all these issues sometimes but I can see progress. I now have two permanent setups, I have two modded cameras with cold finger regulated peltier cooling, and most of the automation is now under control. Onwards and upwards I say!
