Hi Tinwe,  Welcome to the forum.

Also let me welcome you to the SIGMA 8 Club?

We too have a Sigma 8mm and a Canon 5d.  And I think I know your issue.

Put the lens on the camera.  Now remove the lens cap.

Are you holding 1 or 2 pieces of the lens cap?

The lens cap is made from 2 pieces.  A disk and a ring.  The friction ring holds the disk cap in place.  Be sure to remove BOTH RING AND DISK cap.  Now you should get a full 180 degree view.

If this is so.... then welcome to the Sigma 8 Club.  Yes I too did this.. but ONLY the first time.

Now you can use Panoweaver's full circle stitching option.  Not the drum option.

ROFL another falls into the same old trap. Always good for a smile

Regards, Smooth

I too have felt the shame! Took me several months before I figured it out...