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Very good effort Grant. you'll be singing once you get your autoguiding going and start getting 7 or 8 min subs.
As for coma, remember the 55mm to chip rule for the mpcc and remove the T2 thread.
I can't remember if this is cropped, but if it isn't, you might need to re-center your secondary wrt the OTA, see the stars more elongated radially on the right compared to the left, that's either focuser tilt or secondary off center. coma will be uniform once the secondary is centered.
I would suggest, slew to a bright star, loop 1s exposures in your cam with the mpcc on, and check if the shadow of the secondary is in the middle of the white circle. but its important to keep the star in the center of the frame and do this else it'll skew your results.
if the shadow is off centre, keep your hand on one side of the ota and observe where the shadow of your hand appears in the 1s loops and then centre the secondary accordingly.
Other option is to do a star collimation, use a high power eyepiece, something between 4 and 10mm, center a star, defocus and look at the rings. they will need to be centered and concentric.
Apologies if you're already familiar with all of this, just thought i'd explain in case you weren't.
Cheers
Alistair
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