Stunning image. How did you control the central burnout with all the exposures being @ 3 mins each Bill?
I have an M42 image done with a GSO 8" F4 newt (& 20DA) if you want to see it for comparison sake.
I have been using a 5.5" F3.6 schmidt newt as well & yes, I had to adjust the secondary to get my collimation good. What a pain
