Underwater Photography - Equipment

Equipment

Some cameras are made for use underwater, including modern waterproof digital cameras. The first amphibious camera was the Calypso, reintroduced as the Nikonos in 1963. The Nikonos range are designed specifically for use underwater. Nikon discontinued the Nikonos series in 2001 and its use has declined as with other 35mm film systems, but not disappeared. Sea and Sea USA continues to manufacture an amphibious range finder camera that utilizes 35mm film, the Motor Marine III.

Cameras made for dry work can also work underwater, protected by special housings that are made for various digital point and shoot cameras, digital compact cameras with full exposure controls, and SLRs (single lens reflex cameras). Most such housings are specific to the camera. Materials range from relatively inexpensive plastic to high-priced aluminum cases. Housings allow many options, since the user can choose a housing specific to their everyday "land" camera, as well as utilize any lens in their collection. Underwater photographers generally use either wide-angle lenses or macro lenses, both of which allow close focus, thereby eliminating the need for long underwater distance between camera and subject. Digital media can hold many more shots than standard photographic film (which rarely holds more than 36 frames). This gives digital cameras an advantage, since it is impossible to change photographic film underwater. Other digital versus film photography comparisons apply, and the use of film underwater has declined, as it has on land.

Underwater housings are outfitted with control knobs that access the camera inside, allowing use of most of its normal functions. These housings may also have connectors to attach external flash units. Some basic housings allow the use of the flash on the camera, but the on-board flash may not be sufficiently powerful or properly placed for underwater applications. More advanced housings either redirect the on-board strobe to fire a slave strobe via a fiber optic cable, or physically prevent the use of the on-board strobe. Housings are made waterproof through a system of silicone o-rings at the crucial joints.

There are optical issues with using cameras inside a watertight housing. Because of refraction, the image coming through the glass port will be distorted, in particular when using wide-angle lenses. The solution is to use a dome-shaped or fish-eye port, which corrects this distortion. Most manufacturers make these dome ports for their housings, often designing them to be used with specific lenses to maximize their effectiveness. The Nikonos series allowed the use of water contact optics: i.e., lenses designed to be used whilst submerged, without the ability to focus correctly when used in air. There is also a problem with some digital cameras which do not have sufficiently wide lenses built into the camera. To solve this, there are housings made with supplementary optics in addition to the dome port, making the apparent angle of view wider. Some housings also allow for the use of wet-coupled lenses, which thread on to the exterior of the lens port and increase the field of view. These wet-coupled lenses may be added or removed underwater, allowing for both macro and wide angle photography on the same dive.

With macro lenses, the distortion caused by refraction is not an issue, so normally a simple flat glass port is used. In fact, refraction increases the magnification of a macro lens, so this is considered a benefit to photographers who are trying to capture very small subjects.