Underwater housings for cameras can be made from metal or plastic. Each have advantages and disadvantages but the anti-plastic camp often seems to be the most vocal. In this blog I'm going to layout the pros and cons of both 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 Olympus TG5 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 is a metal one made by Nauticam but then there aren'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. And in the case of some high end compacts such as the Canon G7X MkII 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.
As well as availability issues, there are some arguments against plastic housings.
Durability is often sited as a problem and yes a good metal housing will probably survive more harsh treatment than an equivalent plastic one. 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. Leakage caused by flexing of large plastic housings has been known to occur and is one reason why few manufacturers produce plastic DSLR housings. A good plastic housing will have one solid metal base plate, preferably with more than one point for attaching a tray on to. This will reduce flexing action from the tray and housing being twisted or bent away from each other.
Where there is an 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.
The other advantage for metal housings, that for some has become a deal breaker is that there currently aren't any electronic vacuum leak detection systems for plastic housings. This stems from the slight flexibility of the housing structure being enough to trigger the current systems such as Nauticam's when there isn't actually a leak. Some housings such as Fantasea's Sony A6500 housing do support third party mechanical systems that allow you to test for leaks before a dive and many plastic housings have built-in moisture sensors or the ability to fit one.
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 advice on underwater photography, to book on a course or buy equipment go to our Contact Page for ways to get in touch. We can supply Fantasea, Olympus and Nauticam housings and accessories as well as products by INON, Big Blue and Nautilus.
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