how to get rid of this star pattern ...

[rohanpai]

I was using a 50mm prime pointing towards the southern pleiades. Focus was good

Set at F/2, 5 sec exposure

The star pattern was weird - the stars were trailing towards the outside. And this wasn't just with the stars in the corners.. began right at the centre. 

Is this due to stopping the lens at F2?

[Cobberwebb]

I just sold a Samyang 14mm f2.8 lens for this reason, coma. Even stopping it down to f4 didn't fix it.
I suggest stopping it down and see if it goes away, if not, don't use it for astrophotography.

Even though I got a good shot (see photo), zooming in you can see the star issues.

Edited March 11, 2021 by Cobberwebb