donut shapes in image

[mohmiim]

Hi ;

I just got into astrophotography recently, and i finally got my ATIK 383+L yesterday
tried to use it last night and i got weir donuts shapes in the image (see the attached image)
the stay in teh same spot evenif i rotate the camera, is that a problem in the camera or am i doing something wrong ? (the image had other problems around focus and collimation, but i know how to deal with those)

[MikeM]

That's dust in your image train. You have to shoot flats
To subtract them out.

[mohmiim]

thank you for the hint, i cleaned the front window of the camera and this did the trick