Using Ambient Light in Underwater Photography

In underwater photography, ambient light can be used to create stunning atmospheric shots. Ambient light is available light that is present in the scene and in this case sunlight is the main light source to illuminate underwater subjects. There will be times when you will not have a choice but to use only ambient light. For instance, if you’re trying to capture images of large sea creatures such as whales, they might not be near enough for you to illuminate them with strobe lights. There are also times when ambient light will light up a bigger area than your strobes can cover. If you have strobes, you can use these as fill light in key areas such as the foreground.

When photographing subjects and scenes underwater, you will find that the properties of water is not the same as that of air, and light is very much affected. Water is 800 times denser compared to air and when sunlight hits the water, it diffuses and scatters. The blue light is evenly bounced off at all sides while the rest of the spectrum passes through as normal. This is the reason why water appears blue. The deeper down the waters, the darker and bluer it becomes. Contrast also becomes reduced since water acts like a light sponge.

Staying close to the surface will allow you to take advantage of the intensity of ambient light. However, be prepared for backscatter, which are tiny but visible particles such dust or organisms like plankton that reflect light. They produce a snow-like effect, which appear more prominently nearer to the water’s surface. There are many ways you can avoid ambient scatter. One is to go down deeper but you will have less ambient light. Another is to move with care to avoid dust from clouding up and to also move against the current so that dust will float away from you. Also stay away from swells that stir up dust and sand.

When using ambient light, consider the sun’s position since it is your main light source. The sunlight is at its strongest between 11a.m. and 2 p.m., when it is at its highest point in the sky. This is the time when the waters least reflect it away and more of it penetrates through the surface. You may even chance upon getting a cathedral light effect. This occurs when the water’s surface is calm and flat, and the sun is high in the sky. Shafts of light become visible and the effect can be quite dramatic. When shooting cathedral light, move out of the path of the light and face it instead so you can capture its full impact.

One of the effects of using only ambient light is color loss and contrast. Since the underwater environment can end up appearing mostly blue with ambient light, you can offset this by using filters. Color compensating filters will give your scene a certain hue depending on the filter color while color conversion filter will change the appearance of color temperature. In this case the warming filter option is most often used to offset the cool blue color cast provided by ambient light.