Underwater photography

Startling scenes abound underwater, whether you’re scuba diving or snorkeling. Capturing these colorful, almost alien scenes with your digital camera is well within your capabilities once you understand how to use your digital camera underwater, and the differences between underwater and terrestrial photography. Underwater photography used to be limited to professionals with expensive, watertight equipment and tons of support gear, but the development of inexpensive housings allows you to take many digital cameras beneath the waves and capture the world that exists there.

Let’s step back a few years. Prior to digital cameras, underwater photographers used dedicated film cameras designed to withstand the pressure of working at depths, as well as protecting the sensitive film and camera workings from water damage. The most popular underwater film cameras are the Nikonos line from Nikon, used by the majority of underwater professional photographers. The Nikonos V camera uses standard 35mm film, has automatic exposure calculations, but requires the diver to adjust focus and f-stop manually on the lens. The Nikonos RS, a very expensive SLR, added automatic focus and lens control to the family. Nikon isn’t the only underwater 35mm camera available. Sea and Sea and several other companies offer waterproof cameras designed for film photography, but the Nikons dominates the professional world.

Alternatives to dedicated underwater cameras were developed with advances in plastic and composite bodies. Several companies offer housings for terrestrial SLR models such as the Nikon and Canon families. Digital camera housings enclose your land camera in a clear polycarbonate housing that uses O-rings to seal all access areas from water seepage. Knobs and levers on the outside of the housing connect to the camera controls directly, allowing you access the features of your camera. Depending on the housing used, you may not have all the features of your camera available underwater, but all the basics are usually provided. Housings tend to be expensive ($2000 or so for a top-of-the-line model) and bulky compared to Nikonos cameras. Still, they offer the ability to use an existing camera with advanced electronics underwater.

Simply diving with a waterproofed camera wasn’t enough for film work. Colors in the water start to disappear as soon as you submerge. At 20 feet underwater, colors are almost entirely lost, and film cameras render the whole scene in shades of blue, usually vastly underexposed even with fast film. Flash units are a necessity below five or six feet, except on very sunny days. Underwater flash units provide natural illumination for a scene and bring out the true colors, but for adequate lighting a lot of flash power is required. Underwater flash tends to quickly lose intensity because of the density of water, so high power units are required for anything but close-ups. A typical underwater flash setup with have two or more lights, with 400W flash units or more used.

The advent of digital photography changed underwater shooting. For one thing, film speed effects and color correction could be performed in software, reducing the light intensity needed for flash shots. Also, digital cameras tend to be smaller than film cameras, requiring less housing. Although there is no underwater SLR digital camera currently available, a couple are under development but will be expensive and aimed at the professional market.

Lenses underwater

Don’t assume that the field of view your camera lens presents you with above the water translates to the field of view underwater. Because water is a more dense medium than air, it causes several effects that you need to compensate for. First, distances are deceiving. The fish you think is three feet away is really only two feet away. To gauge distances underwater, many photographers use their arms: extend your arm to the same distance as the subject (or almost touch it if it doesn’t move) and that’s about three feet. Some digital cameras will focus correctly underwater, some won’t. You may have to resort to manual focusing to capture the subject properly.

Most digital cameras have fixed lenses, so your options may be limited when it comes to lens choices. Cameras with replaceable lenses (such as Nikon’s D1) allow much better choice of lens, but these must be changed out of the water, not under!

A lens’ field of view is altered underwater, too. A 35mm lens on the surface will not behave the same underwater. You should experiment to find the effect your camera’s lens has on your exposures. A good way to do this is to photograph a fixed object such as a wreck or coral field at different distances, with different settings on your lens if it is a zoom adjustable, and measure the field of view from the results. Because many digital camera lenses are not quite as rated (for example, a “35mm” lens on one camera actually tested as a 46mm lens), testing your camera is a good idea even if you don’t have a zoom.

Underwater affects the distance you can focus to, too. For example, many short lenses (such as 15mm through 35mm) cannot focus closely enough to capture small animals and fish on a reef. On the other hand, these lenses have such a wide field of view that photographing objects ten or more feet away results in a subject too small to see on the final print. Short lenses are designed to capture reef panoramas, other divers, or schools of fish at reasonably close distances. Medium length lenses (35mm to 50mm) are good for shots of individual fish and animals, although not for close-ups or wide panoramas. Longer length lenses (over 50mm) tend to be of limited use underwater because light from a flash cannot project far enough to illuminate a distant subject.

The most useful lenses underwater tend to be close-focussing or macro lenses. Macros allow you to move in close to static subjects such as coral, anemonae, or slow-moving animals like starfish and nudibranches. Close-focus lenses allow small fish to be captured from a distance of less than a foot, although skittish fish require patience.

It is unlikely that you will be able to use the viewfinder on your camera underwater, and use of the LCD display tends to drain batteries quickly. If you do a lot of photography underwater, you will quickly develop a feel for positioning and distance without having to look at the camera. This skill is handy not only underwater, but also on land, too! It lets you get snap shots that you’d miss if you resorted to the viewfinder or LCD.

Digital camera CCDs react differently underwater than film. The color sensitivities of CCDs are different than film, of course, meaning that the colors you see underwater may not be the same as those rendered by your CCD, even with proper flash illumination. Don’t rely on a camera’s built-in flash: it isn’t powerful enough to light up even close fish or animals. Instead, invest in a high-quality underwater strobe, or rent one at a local dive shop. Strobes attach to most housings through a waterproof connector.

Handling underwater cameras

Diving with an underwater camera and flash setup is not for the novice diver. Working with a camera requires concentration on the camera and subjects, not on the diving itself. If you’re a scuba diver, you should have total control of your buoyancy and be familiar with your dive gear before tackling underwater photography seriously. Most underwater cameras and flash gear is neutrally buoyant.

The techniques involved in photographing underwater take a while to master. Perhaps the hardest lesson is to properly frame your subject, taking in account distortion from water, distance to subject (which is deceptive underwater), camera lens, and flash coverage. Maintaining your position to photograph a subject without scaring the target or drifting away requires patience and practice.

Most successful underwater photographers use two flash units positioned at angles on either side of the camera. This provides natural even illumination, but means you’re handling about 30 pounds of gear (which is almost weightless underwater) requiring both hands to operate. Make sure you have someone who can hand you your cameras when you enter the water, and also take them from you when surfacing. Moving in and out of the water with a bulky camera setup is an invitation to damage the equipment or yourself in the process.

Not a diver? Don’t want to lug 60 pounds of dive equipment and cameras on vacation? Try snorkeling instead! Some of the best pictures of underwater life can be captured close to the surface, easily within snorkeling reach. Reefs tend to be close to the surface near shore, with fish and coral life abounding. Underwater housings for cameras can be used without flash near the surface, as colors will render almost naturally from sunlight alone. Snorkeling is also a great way to learn to handle your underwater housing and learn the skills necessary to use your camera when diving.

Camera housings and diving

Housings for cameras range in price and features over a huge range. So-called “water resistant” housings are inexpensive but tend to leak when submerged, even at shallow depths of four to six feet. Unless you are willing to risk losing your camera to water damage, avoid water-resistant housings.

True underwater housings are usually made of polycarbonate (clear plastic) or a combination or polycarbonate, plastic, and rustless metal. Housings are designed for specific cameras, so make sure you select the correct housing for your model. Housings are usually rated for a maximum depth, beyond which the housing could leak or crack. Most underwater housings are rated to 200 feet or more, well beyond the safe limits for no-decompression diving of 120-140 feet.

Expect to pay quite a bit for a good housing. There are several vendors of housings, and not all support all camera functions. Typically, housings range from $750 to $2,500 depending on the camera and features. (The housing usually costs more than the cost of the camera that is inside, making underwater cameras such as the Nikonos a better value!)

If you plan to use your camera underwater on vacation or as an experiment, consider renting a housing from a local dive shop. Most dive stores maintain a few rental cameras and housings, and a week’s rent of a hundred dollars or so is much less expensive than buying a housing that you’ll use only once.