How We take Underwater Photography

Our purpose is to explain what equipment we use. It is not a comprehensive guide to what equipment is in the marketplace, but only an overview of the strengths and weaknesses of equipment we're quite familiar with.

We started with VHS-C, went to Hi-8 and quickly embraced digital video. We now dive a Sony PC-120 camcorder in a Light and Motion housing. This video camera will also take still images at twice the resolution of the video, more than adequate for Web display. For higher resolution still photography, we use an Olympus C4040 digital camera housed in a Light and Motion Tetra housing.

Video housings are usually heavy on land and awkward to handle during entries and exits. They usually will sink if dropped. We tie ours with wrist lanyards, which saved the housings on several occasions. On the other hand, a negatively buoyant housing means you can position the housing on the bottom and begin recording and swim away, either to capture natural behavior of shy species, or to get in the picture yourself.

The watertight seals of housings are more robust than those of underwater still cameras, which will flood if the photographer is not very careful about proper maintenance procedures. Housing o-rings are easier to check and maintain.

Setup before the dive is critical. A small oversight can leave you unfunctioning either for the dive or for the rest of the trip. You must remember to turn on the camcorder's power before putting the camcorder in the housing. Position the camera's control levers correctly. Check that the viewfinder is set up correctly. The camcorder and light batteries must be fresh. Waste a few seconds of tape to check out the operation before you finish suiting up. These procedures sound so elementary, it's almost an insult, but we've both made every one of the implied mistakes.

The housing port gets dirty from natural sea water. Drops that don't sheet off spoil your surface shot of the dive boat. Even under water, the picture won't be sharp through a dirty port. We wash the port as we do our masks, with Lemon Joy dish detergent. Once assembled, we take care to keep the housing out direct sunlight to keep it cool. Otherwise condensation will occur when we take it into the cold ocean.

Still photographers use strobes to light their subjects. Underwater video uses flood lights. U/W floods generate plenty of heat, and generally can't be used out of water. The light illuminates a very small area. Further than about three feet, the flood can't compete with the blue ambient light. Big studio productions use huge movie lights powered by generators on a boat.

Unfortunately, scaring and blinding the animals with the flood lights is unavoidable, especially at night. It's pitiful. Blinded fish blunder into the reef. Basket stars collapse in apparent anguish at the painful touch of the light.

On the other hand, we have met several fish that make a living by hunting with divers. Predators as diverse as barracuda and tarpon meet night divers and persuade them to shine their lights at prey.

Battery chargers, both for the camcorder and lights, generate lots of heat. They require plenty of attention to keep them from overheating in the tropics. Some resorts recommend that we not charge batteries in the hotel room, because the current isn't suitable. In such cases, the resort provides another location where they have installed suitable electrical connections. It isn't as convenient, but it's better than burning up the chargers.

Diving is a non-verbal experience. Natural sounds include the clicking of shrimps, parrotfish crunching the coral, and the excited sounds of divers trying to point out the stingray, rarely, whalesong. Mostly you capture the breathing of the diver and boats passing overhead. Some housings have an external microphone which allows at least some of the natural sound to be useful. Otherwise the whine of the camera motor in the housing interferes with the sound.

Sunlight penetrates best between 10 a.m. and 2 p.m. The density of water -- 600 times more dense than air -- reduces sunlight penetration. The ocean absorbs the long wave length light (the red end of spectrum) first. Short wave length light (the blue end of spectrum) is absorbed last.

Horizontal distance reduces light. If you are ten feet deep and ten feet from the subject, the water between you and the subject absorbs red and orange light as though you were 20 feet deep.

The clarity of the water affects the amount of light. The California coast's abundant upwelling of plankton and particles reduces visibility and scatters light. Turbid water discourages long or medium shots. Backscatter from suspended particles interferes with lighted shots. You can reduce backscatter by aiming the lights to the side of the subject instead of straight on.

Color correcting filters are important for video taken in natural light at depths greater than 15 feet. The filter reduces the amount of light by about two f-stops, reducing depth of field. Some divers put the filter on the camera before they put it in the housing, and cannot remove the filter to adjust to changing light. Our housings allow us to move the filter out of the way when we're near the surface. If we forget to move the filter, the video comes out sunset orange.

Focus is tricky through the dive mask and ports. When we were shooting still photos using manual focus, we had great difficulty making the image sharp. We coped with that by adding a diopter to the right eye of the mask. To determine what diopter to use, I took the housed camera and dive mask to my optometrist�s office. He was only mildly surprised, because people often ask for special glasses for reading, playing music, working at a computer, or other tasks that aren�t well suited by your current glasses or contact lenses. The diopter helped immensely.

With our current cameras, we rely on autofocus to provide a sharp picture. Modern camcorders and cameras are very good at that. We must be careful to avoid auto focus searching -- that is, the picture is fuzzy because the autofocus isn't sure what the subject is. Once we have the objective in focus, we turn auto focus off.