Underwater photography has become increasingly popular as more easy-to-use cameras appear on the market designed for this purpose. While at one time this hobby was limited to professional divers and photographers, today basically everyone is trying their hand at it. However there are several “tricks of the trade” that need to be followed with underwater photography – basic lighting advice is one that can make a big difference in image quality.
One common problem which often arises when taking underwater shots, is the bluish hue the photographs can take on. Because water is 800 times denser than air, it absorbs light more readily, with different colors being absorbed as the depth is increased with reds, oranges, and yellow diminishing first, and blue being the last to fade. This effect can also reduce image sharpness and contrast, but with the correct lighting it can be remedied.
The use of a “strobe” or artificial light provides an effective workaround for this issue. Strobes emit daylight-balanced light which helps maintain the original color shades and intensity, and also add shadow, texture, and contrast regardless of the depth at which the subject is located.
Strobe or flash is intended for use as a supplementary source of lighting. Typically, the photographer must find just the right balance between natural sunlight and strobes, with the exception being the interior of a structure such as an ocean cave or a shipwreck, which may have very little or no natural light, in this case strobe light may be used exclusively, along with a wide angle lens to capture the image.
Essentially all water, no matter how clear it appears, contains the microorganism, plankton which presents yet another photographic challenge. When flash reflects off these tiny particles, it creates an undesirable visual effect known as “backscatter“. This can be avoided by positioning the strobe so it is not directed at the axis of the camera lens, effectively bypassing the water and only illuminating the subject.
Although technological advancements in digital photography have attempted to address the color-loss issue associated with shooting underwater, it does not eliminate the need for appropriate lighting. The custom white-balance feature can be helpful in maintaining color, but is generally restricted to only shallow depths, and color balance settings can cause some details including the water to appear unnatural. Flash stands alone in its ability to light up the subject and make it stand out from its background, an effect which cannot be duplicated using just software.
It is possible to rely entirely on natural light as the lighting source for certain subjects, provided certain criteria are met. A wide-angle lens should be used, the photographer should stand as close as possible to the subject, position the camera no more than one or two inches below the surface, sunny days are best, clear water will produce better results, and set the camera’s priority to shutter release over focus.
One can expect that it will be necessary to spend a considerable amount of time on post production work to make photos taken underwater look their best. A good place to start is to adjust the white-balance by boosting the saturation and luminance of the warm colors while lowering that of the cool colors. Applying lens profile correction can help reduce wide angle distortion, then one can address the issue of increasing the contrast.