Lagoon and Trifid

Thank you! From the TS 0.79x reducer, it's a shame it doesn't cover full frame, so I have to crop.

I'm also seeing crosses drawn in the corners; I wonder if this is a characteristic of some flatteners or the telescope itself. I've also acquired an SW80 and am trying to fit a flattener from a Chinese doublet to it, and I'm observing the same pattern.

Here, several factors are likely at play. First, the imaging was done with a full-frame sensor. Second, I didn't have the necessary spacers to precisely set the backfocus distance, so it was offset by about 4-5mm.