Still a work in progress, mastering the QHY268M with the Optolong LRGBSHO filter set. Seems like a setup with reserved filters is required for the Esprit 100 ED with the original flattener, in order to avoid strange reflections from bright stars such as Deneb or Sadr. Shooting a familiar target here.

Technical details at Astrobin.

Backyard astrophotography in light-polluted Cologne-Dellbrück (SQM 19.8)
Skywatcher Esprit 100/550 ED, Skywatcher Flattener, Optolong Ha 7nm / QHY268M
OAG with Lodestar X2
Mount AZ EQ6 GT
Image acquisition: CdC, NINA, PHD2, dithering
Ha: 19 x 600s, mode 1, gain 56, offset 10, -5C, 2×20 flats, 50 bias, 20 darks
Data calibration/integration: PixInsight
Image processing: PixInsight, Lightroom