I`ve been shooting with a nikonos V for several years now mostly with a sea&sea 15mm: I am about to go digital(dslr own a d300) and have questions about focuscontrol for wideangle photography:
1. If I continue with manual control for example setting focus at 0.70m and a big aperature as I´m used to do.Where will I then get the focus (much talk about virutal image created by the dome haven`t quite grasp that)?Will it be diiferent compered to my nikonos V?
2.Are most people using autofucus with focus ligh?t What´s the techique there? for example a large fish approaching first you photograph it at about 1m the it gets closer till say 0.5m you don´t have time to change the angle of the focus light? Maybe i won´t need one? Will be diving in the bahamas?
aswers much appreciated
regards jacob
for wide shots you won't need a focus light. if you're tryign to shoot a moving fish, just put the camera on continuous focus mode (AF-C - the control is just below the lens release button on the front of the camera C-S-M). Generally you can autofocus and not worry too much with wide stuff as you get heaps of DOF. You can set a manual focus to the hyperfocal distance if you're not shooting a super close subject, though the focus distance you set (say .7m will actually be set on something further away than .7m, thought i'd bet ur DOF will prob include .7m anyways with a wide lens) check www.dofmaster.com for hyperfocal distances.
so yes, focus distances on your dslr lens are designed for land use and will not coincide with distances uw, due to the closer virtual image, which your nikonos lens is set for in the first place. but its really not much of a worry. i'd say just set it on autofocus, use a decent aperture and you'll be fine. cheers,
chris
I use autofocus with my D300 underwater, however, I can see the advantage of using hyperfocal distances for wide angle stuff. This would allow you to maximise sharpness of near objects while maintaining sharpness of distance objects, although light fall off might negate the need for sharp distant objects.
Choosing the right diopter on the lens could negate the effects of the dome port and so you could rely on the actual distances on the scale on the lens. The big problem would be getting a good view of the scale as some ports may not let you see it.
