When I was setting up my kit, I talked with Scott at Bluewater Photo in Los Angeles. He said the difference in the 9-18 and the 8mm is whether you want to get nice snaps from every underwater excursion or do you want to get that one-of-a-kind photo that may make you miss some others. The 9-18 is for the former and the FE is for the latter. Since I just shoot for my own enjoyment and have been shooting uw photos for some three decades I chose the latter and got the 8mm Panny lens. While I haven't been able to get into the water with it as much as I would want, I did have the opportunity to dive Catalina Island in SoCal last month with the camera (e-m5) and the FE. I found the lens to be somewhat limiting, but I did get some nice shots with it. The best being of a Garibaldi who decided to attack the dome port (probably saw a reflection of himself). Here's that photo, something I doubt I could have gotten with the 9-18.