curious rings

[robulaic (Robert)]

Just took out my new AT6RC for a spin with a dslr.
Orion was up so I tried the horsehead for the first time.
Upon examining the images I noticed some strage formations in the shot, two small and one large.

Does anyone have any ideas as to what they may be and how to get rid of them? I am using the recommended field flattener (ATFF)

[Atlantis69 (Simon)]

Looks like dust bunnies to me.

[cfranks (Charles)]

Dust bunnies as said. They are very out-of-focus specks of dust in the optical path, the smaller the bunny, the closer to the imaging chip. Easily removed by using Flats, images of just the optical path errors (see elsewhere for how to take them). Welcome to the world of image correction/calibration.

Charles