Thanks for the tips! I bought a Nikon D7000 today for 1k brand new and will get the housing, strobes and lens this weekend before my trip! For housing, I really like Subal and Seacam even though they are more expensive but far more user friendly and the pros favor these housing types.
Well shoot, if your budget is high enough to look at Subal and Seacam then go for it. Although, I also know of some pros that favor Nauticam and for good reason, innovative ergonomics. My set up:
Nauticam D7000
MACRO:
ext ring 30 w/ Macro Port 60 (67 mm thread version)
Allows for my three macro lenses to be used; 105VR, 60mm and 40mm
For supermacro I have the +5 Subsee wet diopter for the 60mm and the +10 subsee for the 105VR
WIDE:
Ext ring 20, Nauticam 8.5 dome, Zen 100mm Mini Dome
Lenses: Nikkor 10-24 and Tokina 10-17.
Ext ring 20 +30 allow the proper extension for the Nikkor 10-24 behind the 8 inch dome
The Tokina 10-17 can go behind the 8 inch dome+ 20mm ext ring for easy over/under shots or behind the Zen 100m dome for close focus wide angle shots (the 40mm also works behind the zen100mm for convenience.)
Two Inon z240's via Fiber Optics so far is my method of lighting.
Overall I'm really happy with this set up though haven't had the chance to test the 10-24 on sharks, as was mentioned, but I bought it for that specific reason since I am headed to Papua New Guinea in October. In my opinion, sharks are only worth shooting if you can get close enough to light them properly. If you shoot them with a longer lens, you might fill the frame, but you are shooting through too much water which will lack sharpness contrast and impact.
I don't really understand the popularity of the Sigma 17-70mm. For reef fish it may work fine, but if you really want GREAT macro or wide shots it won't do either. IMO For really great shots, it's best to stick with one range, macro or wide... and choose wisely before the dive.