You may be asking yourself what’s all the fuss about? I know how to use a camera – I’ve been taking pictures for years without any problems. Well, yes, but several things make underwater photography especially challenging. Light levels in the underwater water world are much lower than we are used to at the surface. There are several reasons for this.
First of all, clouds or haze can reduce the amount of light hitting the surface of the ocean. So, on a cloudy day, things will appear much darker underwater than on a sunny one.
Not all of the light that does strike the surface of the water actually goes into it. If the sun is low in the sky, the light will be reflected back into the sky and not go underwater. On the surface, you normally just have to think about the effect of shadows when shooting in daylight. Underwater, time of day has a far greater effect on the amount of natural light available underwater.
Another thing that will impact the amount of light entering into the water is the amount of wave action. Even if the sun is relatively high in the sky, if the surface of the sea is very rough, then light will be reflected away making it much darker down below. If the conditions are flat and calm, most of the light will go into the water. Even once the light has entered the water it becomes dissipated. Some of the light energy is absorbed by the water as heat. The remaining light can be scattered by sediment, plant and animal life floating in the water column.
The next big difference for scuba diving and photography is the fact that water acts like a giant filter. This color calibration chart on the left was photographed in only 20ft of water, but you can see that most of the red and orange has disappeared. In fact, red starts being absorbed in as little as 10ft of water. By the time a scuba diver gets to 80 ft, only the blues are left as shown in this photo taken in 100ft of water.
Sea Dwellers Dive Center of Key Largo