Hi Guys! I've been following you for a while and I've always been very impressed with your results. Thanks for your many posts here, youtube, reddit, etc.
I have a similar imaging newt to the Orion that you use, its an Explore Scientific 208 f/3.9. Like you, I am also using a Baader MPCC Mk III and a Canon DSLR. I've played around with the MPCC backspacing using .2mm shims, but have not found spacing that sufficiently eliminates the coma. Have you done anything to adjust your backspacing? Or are you using the default, out of the box settings with the MPCC screwed right into an 11mm thick T-ring?
Second question, how tight do you leave your collimation adjustment knobs on the primary? I've been leaving mine very lightly finger tight in order to avoid pinched optics, but I worry this might not be enough to hold the heavy mirror in place when you slew, effectively ruining my collimation. Should I torque those suckers down snug?
Lastly, have you had any issues with camera tilt from the heavy DSLR hanging off the focuser? The combination of the fast f/3.9 and the MPCC seems very critical of even the slightest tilt or deflection, and again, this seems to be a moving target depending on where the telescope is pointing.
I am currently imaging with two other telescopes, both refractors, without such problems. But there are just some objects where having a big light bucket and 800mm focal length just seem like the right fit. I'd love to hear some advice from someone who has their newt dialed in as well as you guys do.
Thanks for any suggestions, and please keep up the fantastic work. Clear skies to you!-Tony