Underwater Digital Photography Tips
Explore another world – by Underwater Digital Photography Tips
A range of housings makes it relatively easy to shoot underwater, and digital Cameras
take care of much of the uncertainty and colour problems.
Underwater photography is highly specialised, and the diving techniques involved
need to be learned from a qualified ‘instructor. This applies to snorkelling as
much as to scuba diving. Remember that the most interesting places for underwater
photography, such as coral reefs, can have currents, sharp rocks, and a number of
creatures that defend themselves, sometimes very actively, by stinging or biting.
Housings
There is a fairly wide range of submersible housings for digital cameras, but the
basic choice is between those that are adaptable and fit a number of makes, and
those that are custom-designed for a specific model. The best housings, which can
be used at serious scuba-diving depths, are expensive.
Flash
A Flash is virtually essential for close-ups at any reasonable depth, particularly
with active, moving subjects. The improvement in colour intensity and contrast is
marked.
Near the surface
You can shoot without flash within a few feet of the surface, if the water is clear
and the sunshine bright. The main precaution is white balance.
Light absorbing water
Water absorbs light, and the deeper you go, the darker it gets. Also, water absorbs
light selectively, starting with the red wavelengths. Because of this, the deeper
the water, the bluer it appears, and even though the camera’s white balance menu
can accommodate the colour cast down to a few feet below the surface, the results
lack the saturation and contrast of pictures taken with flash. For scenic shots,
showing more than just a detail, natural light has to be used, but they are nearly
always more successful with flash added for the foreground. Flash is essential at
depths below a few feet, and underwater units are normally mounted on an arm above
and to one side of the camera housing. This off-axis position helps to avoid a special
problem in all but the clearest water — back-scattering, in which water particles
between you and the subject are lit up to look like falling snow.
Domed port
The higher refractive index of water has an apparent effect on lens behaviour. Basically,
lenses behave as if they are a longer focal length. One correction is to use a
port in the housing that is domed rather
than flat. This cures the problems of size and distance, although the angle of view
remains narrower than in air. However, it has a side-effect: an ordinary lens will
no longer focus on infinity. To restore normal focusing, add a supplementary close-up
lens or, for an SLR, a thin extension ring.
Dome ports also correct the problems of distortion and poor resolution close to
the edges of the picture, and so are always better than the cheaper flat ports.
For the best performance, the curve of the dome should match the focal length of
the lens.
Equipment care - Follow theses top tips by Underwater Digital Photography
Tips
Shooting underwater can be tough on your equipment. Sand, grit and crystallized
salt can cause leaks by becoming lodged in the 0-ring groove, if they are allowed
to build up after several dives. Take these standard precautions:
i) Check a new housing by submerging it without a camera. Do this first in
a tub or bucket of water and watch for tell-tale bubbles, and then take it to the
maximum depth that the manufacturer recommends. Back on the surface, check the interior
for drops of water.
ii) Between dives, wipe down the housing, your hands and hair before changing
film. If possible, rinse the housing in fresh water before drying it. When returning
to the boat or shore after a dive, do not leave a housing out in direct sunlight;
being sealed, it will heat up very quickly and this can cause condensation and damage
to the lens
iii) At the end of a day’s diving, first rinse the equipment in fresh water
by immersing it completely for at least 30 minutes to dissolve all the salt, then
hose it down. After washing, dry the outside thoroughly with a clean cloth, and
then open the housing, remove the camera, and pull out the 0-ring. Clean the 0-rings
and their grooves with a cloth soaked in fresh water and with cotton buds. Wipe
them dry with a clean cloth and re-lubricate, but lightly. Too much 0-ring grease
prevents a tight fit and may cause a leak. It also attracts grit and sand. Finally,
reassemble and protect the port with a cap.
Here at Underwater Digital Photography Tips we hope you’ve enjoyed this article
on underwater photography. Why not try one of our other Photography Tips articles.
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