For those interested in the thread, I did find some example shots of the 12-24 F4 and 16-35 F2.8 Sony lenses underwater here.
I'm thinking that the 16-35 should be enough to start with for the types of diving I typically do. It should be wide enough to do some fish schooling, turtles, etc. as well as having some zoom range in case I can't coax sharks to come close enough. In the future I may go the fisheye route rather than an ultra wide (weitwinkel) zoom. Maybe I'll wait and see if someone comes up with a native fisheye, and there's always the Metabones adapter if I end up booking any Manta encounters in the near term.
I thought I would use 16-35 more than the 24-70, but it ended up being the opposite. For my needs 24mm seems to be wide enough and 70mm is decent for closeups.
Interesting. I'll have to see what it's like actually on the camera. With my current compact, I'm either shooting macro with diopter and fully zoomed, or I have the ultrawide (weitwinkel) (162 degree) wet lens, zoomed in just enough to stop the slight vignetting with my setup. It's incredibly rare that I feel the need to zoom except in those occasional 'sit on the bottom with crazy current while the sharks hang out in the channel' type of dives. In all other cases, I just try to get closer to my subject.
I did order the new 24-105mm F4 lens to go with my new camera, but was only planning on using it as a walk around/travel photo lens. I'll have to see what it would take to get it into the housing. Judging by the video reviews I've seen the lens extends quite far when fully zoomed, and it's already about 20mm longer than the 24-70 already. It might need a longer extension to keep it from hitting the port. The minimum focus distance is a little short as well. I'm not sure how useful it would be to me.
Voigtländer e-mount 12mm F5.6 ultra wide (weitwinkel) (weitwinkel) Heliar aspherical III (121° angle of view), also comes in a 10mm and 15mm variant. Could these work behind a dome port? I am definatly loving these for landscapes. The F1.2 40mm also seems like a great prime lens.
I think (I may be wrong, I'm still pretty new at this and trying to play catch-up) that you'd have the same issues as the 12-24mm. You'd need a very large dome in order to get good sharpness, as well as the right port extension in order to get the lens in the correct place. It should work, but could end up being very cumbersome (which may not matter with enough time spent balancing things out).
I guess I'll have to wait and see when some of this stuff is actually released. At this point it's mostly just me speculating and getting myself worked up. I've been waiting on this upgrade for quite a while. I feel like a kid on Christmas Eve