Whether to use an amphibious camera or a camera with an underwater housing is not a simple decision. Some like the practical, user-friendly single-piece tackle, while others don’t mind toting around a bag of more complicated equipment.
Your intended underwater use will help you arrive at the kind, type and the model best suited to your needs. It also helps keep your choice within an acceptable price range.
Some might be happy using the automatic and “scene” functions of a camera. For others, it’s important to use manual settings. Fortunately both types of cameras offer these options.
Amphibious cameras are single-piece equipment, usually compact in form. They are watertight or “water-resistant” and well-protected against dust, cold and an occasional bump; important considerations for an outdoor-type photographer.
Less attractive features of amphibious cameras can be their relatively modest zoom range. Because of a more solid build, they also weigh a bit more than ordinary compacts.
Amphibious cameras have limited operating depths, usually between 3 and 12 meters. This is suitable for skin diving and snorkeling, less so for SCUBA diving.
When considering an amphibious model, check the type of battery it uses. AA alkaline batteries are much easier to buy in remote areas than Li-ion batteries, which require a dedicated charger. It’s important to plan your power source and recharging method before traveling to socket-less places such as the extreme outdoors. Always bring spare batteries!
These battery considerations also apply when using a camera in an underwater housing.
Underwater camera housing
The biggest advantage of using a land camera in an underwater housing is that you’re already familiar with it. Also, you can reach some diving depths that are off-limits with current amphibious cameras.
Every quality underwater casing consists of a main body, camera inset door, lens port, sealing elements, outside buttons or keys that correlate with the camera setting elements, and sometimes the sealed electrical contact for a wired flash unit connection. Most cameras in underwater casings are equipped with electrical drives and are operated per push buttons instead of complex gearing.
The body of the camera casing is usually made of Perspex (airplane window material) or, less frequently, ABS plastic or metal such as aluminum alloy. Metal casings are used when operating depths and corresponding pressures exceed those visited by recreational divers, roughly deeper than -80 meters.
High priced metal casings can cost more than the camera inside but make it possible to go where no other camera goes. Perspex and/or ABS casings are usually limited to pressures of 5 or 6 atmospheres (-40 to -50 meters seawater). Deeper than that, depending on design, flat surfaces of the cameras or casings begin to bend inwards, causing inner parts to go out of alignment or press things that shouldn’t be pressed.
Compact vs. interchangeable lens camera casings
Compact camera casings usually do not have interchangeable lens ports that casings for interchangeable lens cameras must have to accommodate lens systems of different sizes. There can be problems with any lens that changes size when zoomed, so it’s preferable with any port to use a lens system with internal movement.
If you plan to take an interchangeable lens camera underwater, think about a casing with corresponding lens ports for the lenses you will want to use. It rarely comes cheap.
Lens ports are made of plan-parallel, single or multiple-sheet glass to withstand the maximum operating depth pressure. Some ports are level; those for wide angle lenses are domed to allow for the extra wide field-of-view.
Digital cameras with manual lens operations need casings with some rotational means of achieving those functions, and that requires extra lens gear and corresponding sealed rotating elements reaching those from the outside. This in turn presents another spot requiring some maintenance that may involve certain special tools, adequate spares – and knowledge.
Sealing of a mechanical command
The sealing of a mechanical command on a water resistant camera is usually designed in two main ways. One looks like the surface of a TV remote.
When you press a rubber bubble, the metal plate closes the circuit. Releasing the command moves the metal plate to its original position. This principle is very pressure-sensitive and thus unusable in any greater depth. It is, however, quite sufficient to protect your device from rain, spray and humidity.
The more acceptable way is achieved with o-ring sealed tiny nail-like metal stick protruding trough the casing directly over the camera key it is supposed to activate.
An internal spring fights the water pressure, but requires finger pressure to activate a command. The outside layout of buttons-on-sticks coincides with the camera keys and the operating is logical and simple.
Since the o-ring and the sides of the groove it lies within are lightly greased, the movement and actions caused by finger pressure occur smooth and symmetrical. The grease also helps the rotating moving part to slide within the formed seal without noticeable change in the force required to operate such a command.
In case of a hatch or port, where there is no movement once it has been closed shut, the deformation and sealing process is absolutely solid if the o-ring surface is not cracked and if the light layer of grease has been properly applied.
It’s important not to over grease the ring and sealing surfaces! Surplus grease attracts sand particles, hair, lint and such, and can have unwanted effects on camera usability.
The o-ring material will dictate the correct kind of grease to use, so follow the manufacturer’s recommendations. Check between dives to see if there is any dirt or sediment sticking to greased surfaces. Dirt of any kind has to be removed since it will damage the seal if the pressure forces it to cut into the ring or groove sides.
A word of caution: There are some new materials used where the manufacturer explicitly forbids the use of any kind of grease on the sealing elements. Follow the manufacturer’s instructions and be sure to clean all foreign matter from the sealing areas, using chemically neutral means (water) and only blunt tools.
Manufacturer’s or Third Party Underwater Casing?
Whichever camera model you find most suitable for your intended underwater work, see if the manufacturer also produces a casing specifically for it. When buying from an independent manufacturer the case may be designed for more than just one type of camera. This can require inner adaptations that may not be precise, or some of the buttons may not correspond ideally with their inner command keys. Be sure to check all camera functions in such a casing before buying.
Related reading: Watertighting