The ASI cameras like the 120 are prone to presenting Newton Rings in Ha.
I'll find an example... but they appear as regular dark/ light bands across the whole image.
The cause is interference of the monochromatic light between the cover plate and the CCD chip in the camera.
The only solution I've seen so far is to slightly tilt the camera relative to the optical axis to change the effective thickness of the cover plate.
I have the same camera and don't find it bad at all for the newton rings, they tend to appear more when using a barlow for me but without one they are rarely an issue. Sometimes you can see them onscreen but they always process out.
