Anything taken underwater that has an air-space within it will have a tendency to leak. This sad fact of life used to be never more true than with cameras. There was even the once ironically named Society of Nikonos Flooders! So the philosophy of underwater photography combined with the realism of the likelihood of a flood coined the advice, “It’s not if, it’s when.”
So why does something that is designed to keep the water out, let the water in? Well, it’s all down to the fact that you need to access a submarine housing from time to time, whether it is to renew a battery or replace a memory card. The seal at the point of entry is usually effected by an O-ring that sits it a groove and abuts another surface when the unit is closed up. If the point of contact between the O-ring and these surfaces is not scrupulously clean and smooth, free of any foreign bodies like hair or grit, the seal will be broken and water at the pressure of depth will hose through the so-caused gap.
The O-ring must be lightly greased. This does not help it seal but simply allows the O-ring to flex and move as the two surfaces are offered up to each other. Too much grease can in itself cause a leak. You should just put on enough to make it glisten.
Passing a clean O-ring between your lips can help you detect if it has any grit or hair clinging to it and you might do this before you re-grease it. O-rings are often supplied with camera housings as spares but the original will never wear out. You would need to damage it with a sharp object for it to need replacing.
So keeping the opposing surfaces smooth and clean and placing a clean lubricated O-ring between them should maintain a perfect seal – but bad things can still happen. Using the wrong type of grease can cause a leak. If you use silicone grease on a silicone O-ring, it can cause it to swell or start to dissolve. Use the right grease - an environmental silicone - even on neoprene O-rings.
Don’t leave your rig in a fresh water rinse tank. Other divers may not be so careful about your precious kit and a careless collision with another object being rinsed could cause some catches to come undone.
Isn’t there a better way? Well, yes there is. If you want a compact camera, what about the Olympus TG4 in an Olympus housing? You will need to maintain the main O-ring of the housing in much of the same way as you would any other make of housing but the TG4 has a second line of defence in the event of an ingress of water into it. The Olympus TG4 is itself an amphibious camera and can be used down to 15 metres deep just as it is. Put it inside it’s housing and, should the housing be found to leak, you will only need to ascend to 15 metres deep and later, open the housing and rinse it in some fresh water and dry it, before you are ready to reinstall it in its housing, first having discerned what caused the leak in the first place.
If you go for a compact in a more elaborate housing, buy a Nauticam and spend the additional £191 on a vacuum leak-test kit. These vacuum leak test are available on bigger more expensive Nauticam housings for bigger and more expensive cameras and nobody in their right mind would eschew the chance to never suffer another leak again.
The vacuum leak test as an integral part of a housing was first introduced by Hugyfot. These housings are available only for more expensive cameras but when they were first introduced many years ago, several owners suffered flooded cameras. The problem was that these housings are securely sealed and locked using bolts. These bolts were sometimes not fastened tightly enough and when the clamshell housing was pushed together by the intense pressure found at depth, the bolts could work loose. When the diver ascended to a lesser pressure, the two halves of the clamshell housing could become loose and a flood was the result. The Hugyfot vacuum leak-test was the answer to this problem (now included as standard equipment on all Hugyfot housings) and Nauticam has more-or-less adopted a similar system.
This is how it works: The camera is sealed inside the housing with a lightly lubricated O-ring to seal out water, as usual. A pressure sensor within the housing confirms it is working and a (red) LED signals that the air inside the housing is at the same pressure as outside.
The air is then vacuumed out of the housing via a special one-way valve using the pump provided. The pressure sensor inside detects that the air pressure is suitably reduced and a green LED shows. Green is good.
The user then waits to see if the green light remains or whether a red light will show instead. It is recommended to wait around 20 minutes. If no air has leaked in, no water will leak in. Depressurizing the interior of the housing has a secondary benefit. Outside air pressure pushes the two parts of a clamshell housing together so firmly that you need not do up any bolts or close catches (should you forget) and you literally cannot prize the two parts apart without letting air back into the housing via the valve provided.
So this cured at one stroke, the problem of Hugyfot users not fastening the housing bolts sufficiently, as well as ensuring there was going to be no leak. Hugyfot cured this design/user defect at one stroke.
Underwater photographers find that winking green light to be very comforting on a dive and never open the valve to let air into the housing until they are out of the water and done using the housing. Now it’s not not-if-but-when, it’s green ensures your costly camera will survive!