Thanks Peter, too big a step size has been my playground for a while, but I’m only using 10 and 15 steps at present. I can see the star image grow and shrink nicely, but it’s EKOS that does not seem to stop before it goes so far as to produce annuli. I don’t get this at all and it’s going past a x3 HRF.
I will keep playing, but one thought that is coming to mind is that the iOptron focuser is not up to the job…