You can look at these and be the judge. I may shoot the lens in a few days with the Zen 200mm dome to see how it looks. Cant get this close with that dome. Most of these shots are very close to the subject. This is also I believe the only full frame system where you can shoot the 8-15 zoom with a 100mm port.
From todays dives using the Canon 8-15mm Fisheye zoom, at the 15mm full frame end and the 8mm circular fisheye ends of the lens.
Nauticam Housing, Sony A7R II, Canon 8-15mm Fisheye zoom, Metabones adapter, Zen Underwater 100mm port, two Inon Z-240 strobes.