For Nexus D70 users - I finally came up with a great setup for the 17-55mm DX lens.
Special 12-24 Port, 60mm extension ring, +4 diopter. Sharp focus throughout the zoom range from corner to corner. Its a very useful focal range for a non-specific dive. I'll post a few pics from Port Hardy as soon as I can sort thru them all.

I have always wanted to the 17-55 underwater in a nexus, do oyu mind if i ask:

a) what the reproduction ration (macro) at the 55 mm end like (i.e. 1:2, 1:3, 1:5, 1:10)- how close can you focus, what would be the smallest thing you could reasonably photograph

what zoom gear did you use (ryan?)

cheers

paul

With the +4 diopter the lens will focus from 11.5 inches to 16.75 inches from the sensor (film) plane, which is pretty close focus. Since this is not a macro lens I have not measured or calculated the reproduction ration. Sorry. When I plan to do macro shots I use the 60 or 105mm lenses. I use the 17-55 as a general purpose lens, when I want to shot a variety of subjects. The zoom gear is a modified Nexus 12-24 gear. The inside diameter is just a bit too large, so I wrapped 3-4 layers of masking tape around the lens & made a tight press fit with the gear. The FP170 dome port did not work well for me (soft edges). The 12-24 port has a larger radius of curvature (190mm) but is physically smaller in diameter because less of the hemisphere is used. The larger radius makes a big difference in results.