Underwater photography done with specialized equipment and techniques is the process of taking photographs while under water. It is often done while snorkeling or swimming. Fish are common subjects, but photographers often pursue shipwrecks, submerged caves, and shots of fellow divers. The waterproof camera is of course very popular with people who enjoy family holidays at the seaside or at lakeside resorts and don’t want to be concerned if their cameras gets wet by falling into the water. When photography is performed while scuba diving, it’s important that the diver-photographer has become reasonably skilled to protect his own safety and that of his fellow divers. The quality of images will be enhanced by good scuba skills because marine life will be less likely to be scared off and the environment will remain relatively undisturbed for the shot. Underwater photographers generally must avoid heavy currents, tidal flows, or poor visibility. The primary obstacle faced by underwater photographer is loss of color and contrast when submerged to any significant depth. The longer wavelengths of sunlight (such as red or orange) are quickly absorbed by the surrounding water, so everything appears blue-green to the naked eye. The loss of color increases horizontally and vertically through the water column, so that subjects far away from the camera will appear colorless and indistinct. This happens even in apparently clear water, such as that found around tropical coral reefs. Underwater photographers overcome this problem by combining two techniques. Getting the camera as close to the photographic subject as possible, minimizing the horizontal loss of color. Serious underwater photographers consider any more than about 3 ft of water between camera and subject to be unacceptable. Using the flash to restore any color lost vertically through the water column. Some cameras are made for use underwater, including modern waterproof digital cameras. Cameras made for dry work can also work underwater, protected by special housings for digital point and shoot cameras. The user can choose a housing manufactured to the specifications of their everyday “land” camera, as well as utilize any lens in their collection. Underwater photographers generally use either wide-angle lenses or macro lenses, both of which allow close focus, thereby eliminating the need for long underwater distance between camera and subject. Digital cameras have an advantage, since it is possible to film underwater without surfacing to change film. Macro lenses, cause less distortion so normally a simple flat glass port is used. Actually , refraction increases the magnification of a macro lens, so this is considered a benefit when trying to capture very small subjects.
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Generally, the flash should be used to supplement the overall exposure and to restore lost color, not as the primary light source. Usually, the photographer tries to create an aesthetic balance between the available sunlight and the strobe. Many modern cameras have simplified this process through various automatic exposure modes and the use of through-the-lens (TTL) metering. The increasing use of digital cameras has reduced the learning curve of underwater flash significantly, since the user can instantly review photos and make adjustments on the spot. Even seemingly clear water contains enormous amounts of this plankton, even if it is not readily seen by the naked eye. The best technique for avoiding back-scatter is positioning the strobe away from the axis of the camera lens. Ideally, this means the flash will not light up the water directly in front of the lens, but will still strike the subject. Many digital cameras have settings that will provide color balance, but an image shifted toward the “warm” part of the spectrum can create background water which appears grey, purple or pink, and looks unnatural. Natural light photography underwater can be beautiful when done properly with subjects such as upward silhouettes, light beams, and large subjects such as whales and dolphins. Digital cameras have revolutionized many aspects of underwater imaging however it remains unlikely that flash will ever be eliminated completely. From an aesthetic standpoint, the flash often adds “pop” and helps to highlight the subject. Ultimately the loss of contrast and color is a pervasive optical problem that software such as Photo shop cannot always adequately deal with. Today cameras are more sensitive to low light conditions and make automatic color balancing adjustments. The small size of fully automatic cameras and camcorders with large view screens as well as long-life rechargeable batteries have reduced the housing size and made underwater photography an easy, fun activity.
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