Hello, I'm off to the Shedd Aquarium in Chicago this weekend and am planning on bringing my D80 & 50mm f/1.8. I figure most of the shots I take will be in low light except for the small Reef Tanks. I figure the 50mm will work best since I can get the aperture opened all the way up to 1.8. My 18-70 is only a 3.5-4.5. Any tips out there on aquarium photography?