I’m fighting back spacing issue / or a lousy flattener issue
I recently bought a Starfield .6 reducer from Canada. It’s made for refractors f7 and above - a 55mm backfocus is stated. I’m still getting comets toward the edge with a skywatcher 100 Ed pro (f9)
And a Nikon D5300- all I had is a ruler and it looks like I have 54mm backfocus.
the test image was bright and field reduced (f5.4)
question 1. Is 1mm really going to give me totally unsatisfactory coma ?
question 2- this may be silly- I have a Starizona SCT corrector lll that totally rocks on my 11” xlt-
now I know it’s for f10 and f11 SCTs - but what do you think would happen if I stuck it in the f9 refractor ???
thanks in advance -