I've tried the 24-85G underwater with my Nexus rig using both a dome (4") and a flat port and had very good results. I also have the D but it's very hard to get a Nexus ring on that lens to provide zoom capability. I did not use a diopter with the G lens although I had a wet diopter for the flat port. My advise for G users is to get a 67-62 stepdown ring, a 62mm lenscap and install the combination permanently (except the lenscap while shooting, of course!). The stepdown ring will protect the fragile plastic threads and allow the use of standard Nikon diopters if you like. No vignetting occurs.
Problem with either of these lenses is that you won't get the magnification you think you will because of the working distances. If you are expecting 1:2 or better I think you'll be disappointed. Good for fish portraits. I've used it for sharks and for frogfish.
I used a Tamron 28-75 with the Aquatica/Kodak on the last trip behind the Aquatica 8" dome. It lacks the close focus of the Nikon 24-85D but it worked (quite well, in fact) in a pinch. I've also been looking for a midrange zoom with decent macro performance for the same reasons Robert has. I think the 24-85 is an OK solution using DX sensors but full frame complicates matters. I've looked on the Canon side and it seems that Canon doesn't offer midrange zooms at all with decent close focus capability. Tamron makes a 28-135 with OK close focus but I have no experience with it. The long end may provide enough working distance for full frame and reasonable magnification.
Eric, you prefer the 17-40 over the 16-35? The 16-35 would appear to have the edge in autofocus because of the extra light but the extra length and lighter weight would be nice on the 17-40. How does the 17-40 AF work underwater using your 1D* bodies?
