I'm using an Ikelite housing for my Sony SR-12 and recently tried the W-20 wide angle lens, and had the same problems. (Actually, I have two identical setups, and they both have that problem.) I was wondering if it was just some issue with the camera being misaligned with the lens, but this ghosting idea makes a lot more sense.
I had a lot of fogging and other issues, too, under demanding conditions, so I'm switching up to a Zen Underwater WAVP80 Wide Angle port, which totally replaces the glass port in the front of the Ikelite housing. It seems to be a lot sharper around the edges than the W-20 was, but it's a lot more expensive, too. I haven't tested it under conditons where ghosting reflections might occur yet.
Can you please tell us more about the Zen Underwater WAVP80 Wide Angle port? I tried to google it but couldn't find anything....
