On my Celestron Evolution 6 I see faint rings close around bright stars as if the star would be out of focus, like the rings we use for collimation. When I do the donut test, meaning out- and infocusing to collimate, everything looks fine, dark dot in the center and rings are not skewed. But when I try to focus on the star I cannot get rid of a few rings very close to the star, no matter how carefully I try to focus.
Is this normal or does anyone have an idea what might be causing this? I don't see such rings on my 12" dobson but other than that I didn't notice anything to be off, planets and moons are sharp and less bright stars are pin point in my SCT.
Edited by SupernovaDust, 06 August 2020 - 04:28 PM.