Flat frames only work if your telescope and camera setup remain unchanged between capturing flats and light frames. Changing focus, swapping filters, or adjusting the optical train can cause mismatches that introduce new artifacts instead of fixing them.
Always capture flats immediately after your imaging session without altering your setup. This ensures the flat frames accurately map dust spots, vignetting, and illumination falloff on your sensor.
Remember, consistency is key to effective flat frame calibration!
