DSLR images really bright

Astroblue17

I'm 100% new to DS photography .I'm have searched the internet for the answer but can't find or understand. My d5600 70-300 lens no filter images come circular white like what is attached. I normally do 800 or 1600 iso and tried lower. I think it happens on any image over 15 secs gets more noticeable when I get on longer times. I know it's auto stretched but even after callibration frames it's not as bad but you can tell it's still there. Not sure if someone has had same problems with on a DSLR or if it's not even a problem.

w7ay

Astroblue17 images come circular white like what is attached

I see a light dropoff only when I stretched your image:

Perfectly normal, and often worse for non-astrographs. With camera lenses, you will find a smaller dropoff by using a dimmer f-number. I.e., an f/11 will have less dropoff than f/2.8.

You get around this by taking "flat frames" (Google it) at the same f-number and focus and with the same filter as what you used for your actual image. And then use the flat flames to correct the images during post processing.

Chen

Astroblue17

I was trying for m101 which I know with 300mm wasnt going to reach. Ill try with something closer range and keep trying.I do appreciate all the advice and knowledge 👍.