I've got a trip coming up in late July to the Sea of Cortez on the Rocio Del Mar. Expected sightings underwater include sea lions (100% possibility), whale sharks (80-95% possibility), sharks (60-100% depending on species) and dolphins, humpback and sperm whales, and mobula rays (40-60% possibility).
I'm using a Olympus e-m5 in a Nauticam housing with an 8mm Panny fisheye and the 12-50 Oly lens in the dedicated port. Lighting is from two YS-01 strobes. I also own the 9-18 mm Oly lens.
My question is, "should I spring for the 4" dome port at this late date? Realizing that I can use the 9-18 and the 12-50 in that port is pretty good, but I won't have any time to practice with it before the trip and the cost ($480 not counting the zoom gears) will definitely cut into my trip funds. Without the zoom gears, I would be stuck with whatever setting I put the lens at before encasing it in the port, but in the 12-50 case, the 12mm setting might be pretty good. I am not sure how sharp either of these two lenses are underwater. Above water, I find the 12-50 to be quite sharp. I've only owned the 9-18 for a little while, but I don't use it too much as most of it's range is covered by the 12-40 PRO lens (used exclusively above water).
Would either of these possibilities be worth the cost at this time?
Thanks for your help!