This adds to the burden you have to carry, and also adds considerably to the cost of your equipment. Camera system differences . Only housed SLR cameras or the Nikonos RS come close to what you are used to in land photography. With these cameras, you actually have to guess how far away the subject is. There is some latitude in this estimate, but that depends on which F-stop you have selected, so there is a stronger element of luck here than there is with a housed SLR system.
Composition is another problem.
With the exception of SLR cameras and one amphibious camera, most underwater systems have viewfinders that do not look out through the lens. While it is possible to find water of astonishing clarity, this is the exception, not the rule. Usually, there is lots of matter suspended in the water, whether plankton, sand, silt or other substances. There are ways around that, of course, and we shall discuss those a little bit later. For now, take a look at what backscatter looks like, on the right, so you will recognize it.