I disagree with Tom and Craig about zooming the lenses to the same points. Of course that would be a fairer comparison - and stopping the full frame cameras down an extra stop would be fairer too! But the reality of a photographer using any of these lenses underwater is that they would not stop zooming out if they needed to. They would use the range of the lens that is fitted to their camera. The tests need to be relevant to actual shooting and it is important to know how the lens you attach will perform (I realise Tom, that you don't dive with your cameras - so can't zoom while shooting - the rest of us do).
I do dive my cameras, however, they can get a lot more 'bottom time' in a day of stream shooting compared to scuba diving.
While not limited by air, there are other limitations such as day length, card size, and at some sites tide (one of my favorite streams has to be accessed at low tide from its seaward end).
There is a need to choose FL regardless of mode used to deploy ones camera. I have used 14mm the most for stream shooting with the DX format, however there are times when wider or even longer would be better. Being able to zoom at the time of deployment or being able to adjust during a shoot would be beneficial. What may be the main advantage of the 14-24 over the 14 prime is its superior resistance to flare. 14 is quite wide, I think the 18- 20 mm FL range would be best for what I do based on recent experience. Thus the 17-35 would also do. I use the 10.5 when the fish are so dense they tend to run right up to and contact the port, it would be these situations where 14mm on FF would be good too.
BTW, Happy Birthday Old Boy!!
Edited by Tom_Kline, 05 February 2009 - 09:32 PM.
Thomas C. Kline, Jr., Ph. D.
Oceanography & Limnology
Housed digital cameras: Canon EOS-1Ds MkII, EOS-1Ds MkIII, and EOS-1D_X; and Nikon D1X, D2X, and D2H. Lens focal lengths ranging from 8 to 180mm for UW use. Seacam housings and remote control gear. Seacam 150D and 250D, Sea&Sea YS250, and Inon Z220 strobes.