Sigma 10-20 on full frame?

I tried it out some years back.  The DC lenses all fit on full frame bodies - they don't protrude further like EF-S lenses.  The only issue is vignetting and image circle.  If I remember, the image circle was smaller than the frame from 14mm down.  At 17mm the worst vignetting was gone.

The image below is pretty bad, I was never going to publish it, but kept it around as a reference.  It was taken with a film body, so I don't have the exif, but I think it was 14 or 15mm.  The lens was the 10-20mm f/4-5.6.