Circular Fish-eye Flair.
This is actually from the first few tests of the Samigon FE on a film camera. It was designed to be on a the normal lens of a film camera to make circular fish-eye images. Until now, I've only used it on digital bodies, getting either rectangular images or ones with only circle arcs at the corners or ends. I should be stopped down about a half-stop more, according to the lens instructions, but was going with what the light required. The flare-starburst outside of the image circle was a complete surprise, though I was aware of the sun being right at the fringe of what I was framing.
Samigon 180-Degree Fisheye, at f11
Super Takumar f1.4 50mm (host lens)
Spotmatic SP, at 1/250 sec.
Rollei Superpan 200
(cross-posted)