Underwater housings for cameras can be made from metal or plastic. In this blog I’ll lay out the advantages and disadvantages of the two different types.

There are two big advantages that plastic housings bring to the table. Firstly they are almost always cheaper than metal housings. This stems from simpler production methods and a cheaper material. For divers on limited budgets wanting to get started taking pictures underwater the cost of a high end metal housing even for a compact camera such as an OM Systems TG7 is a lot to layout. That extra money could often be better used on accessories or to fund some actual diving. So a plastic housing is many people's starting point in underwater photography.

 Secondly nearly all are lighter than their metal counterparts, although Ikelite's polycarbonate housings have a reputation for being often as weighty as some metal ones. With reduced luggage allowances and the weight of dive kit and camera accessories to fit in, a lightweight housing for traveling can be a boon for someone on a budget or travelling light. 

So why ever bother spending the money on a metal housing?

Availability is probably one of the strongest reasons. In the case of those wanting to use certain cameras it may be because they can't get a good quality plastic housing for their camera. Although this works both ways. The only quality housing for the Olympus OMD EM10 MkII was a metal one made by Nauticam but then there weren’t any good metal housings available for the excellent Canon G9X MkII compact camera. For those using interchangeable lens systems, either DSLR or Mirrorless it can be the range of ports available to go with lenses. In the case of some high end compacts such as the Canon G7X MkIII the metal housing systems have short ports available that allow for better results from high end wide angle lenses unlike most of the plastic housing systems.

Depth rating might also lead you to buying a metal housing rather than plastic. If you are a technical diver you may well want a housing with a rating below 60 metres and that means in most cases going for a housing built from aluminium. For example Nauticam housings are rated to 100m.

Durability is often sited as a problem and yes a good metal housing will probably survive more harsh treatment than an equivalent plastic one for longer. But there is probably a narrower margin than critics believe between what will kill a plastic housing and what will do the same for a metal one. Ports, dials, buttons, hinges and locking mechanisms are weak spots to damage on all housings. If you take care of your housing, whatever material it is made from it will likely last longer than your camera's useful life.

Where problems most often occur with plastic housings and not metal is in the event of sand getting into a control such as button or dial. If not spotted and removed promptly wear can occur to the plastic of the housing body or door where the control passes through it. If that wear causes a leak it’s likely to result in you needing to replace the whole housing. If you are regularly shore diving from sandy beaches extra care should be taken when rinsing your housing after dives.

In addition mounting points on aluminium housings like cold shoes and the plates for attaching trays etc are generally sturdier because they don’t require a metal part to be screwed onto a plastic surface. In the case of some housings it’s possible to screw ball mounts into sockets in the housing itself for a more secure attachment than a cold shoe.

Another issue with plastic housings is the problem of the port fogging up on the inside. This is more common when there are warm, humid conditions or large differences between air and water temperatures in the area you are diving. Condensation forms when air inside the housing that is warmer than the surrounding water passes over a cool surface. In plastic housings the port is usually the coolest part of the housing because the plastic housing body conducts heat more slowly, so the port mists up. This is exacerbated in large camera housings such as DSLR or Mirrorless where there is more air to circulate. Cameras that run at higher temperatures also increase the chances of condensation forming during a dive. Measures such as using silica packs inside the housing, only opening the housing in cool, dry air and making efforts to reduce the camera's heat output can decrease the possibility of this happening. With metal housings the internal surfaces cool more evenly and so condensation inside the port is rarely an issue.

Until recently the other advantage for metal housings, that for some has become a deal breaker is that there weren't any electronic vacuum leak detection systems for plastic housings. This stemmed from the slight flexibility of the housing structure being enough to trigger the early systems when there wasn't actually a leak. Several brands including Fantasea have now produced vacuum systems and have revised the design of their housings to provide them as options.

So there are some pros and cons to both systems. But in the end it should boil down to whether the housing and camera combination will give you the best results for your budget.

If you would like to book on a course or workshop or buy equipment email us at info@alphamarinephoto.com  We can supply housings and accessories by a wide range of manufacturers and run online courses and workshops around the world.

We also run an advice and discussion group on Facebook, Alphamarine Photography Q & A which anyone can join as long as they stick to the rules.

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