Here are the first sample images of the newly announced Laowa 4mm f/2.8 Fisheye lens mounted on the Panasonic GX7. You can see how wide this new lens performs.
“Featuring a 210° angle of view, this lens delivers unique circular fisheye field of view on Micro four thirds cameras. The ultra-wide angle view allows photographers to create 360° panorama with ease. Despite the unique & ultra-wide perspective, the lens only weighs 0.3 pounds (135g)…”