Like a lot of people, I've tended to assume that metal is better than plastic. I think most of us have dismissed something for being made of plastic, and I've tended to rate camera bodies to some degree on the amount of metal they contain.
But I'm having to reconsider my position. I recently had the awful experience of hitting a half-grown kangaroo with my Subaru. I was travelling at 80 kph when I hit him - there was nothing I could do about it: the silly little sod just bounded out in front of my car and I'd only just hit my brakes before I hit him. He got up and bounded away, and I continue to hope he had no more than cuts and bruises. My plastic bumper looked a bit knocked around, but when I took it to the panel beaters, they had it back to me in 25 hours. The reason the roo was able to get up and the reason the panel beaters could fix the car in a day? Plastic bumper! Had the car been the EH Holden I got my licence in back in 1967, the roo would be dead and some serious metal bashing would be needed to repair the chrome bumper.
Plastic has its place, it seems.
What's this got to do with cameras? Well, I stumbled across the phrase Sereebo monocoque the other day in relationship to Nikon. I know what monocoque means: most planes and cars have been built using this technique for decades. (For those uninitiated, according to Wikipedia, monocoque is "a structural approach whereby loads are supported through an object's external skin, similar to an egg shell. "
So, what's that got to do with cameras - and what's Sereebo? Well, it turns out that recent Nikons such as the D5500 and the D750 are being built using monocoque techniques. This from a Nikon blurb about the D750:
The D750 is the first Nikon FX-format camera for which a monocoque structure, which serves as the exterior frame that protects the internal structure with great strength, has been adopted. A carbon fiber composite material (new material), has been adopted for the front body, where important mechanisms such as the imaging unit are incorporated, and the front cover, and a magnesium alloy has been adopted for the rear and top covers.
Use of these materials not only helps to make the camera lighter, but also ensure superior strength and rigidity.
(Sorry about the spelling!)
It turns out that Nikon is forming the box around which the D750 is built from a composite plastic carton fibre called Sereebo. This produces a product which is light, strong and even shields the internals from electromagnetism. (The D750 still has magnesium alloys, but on the back where there's so much wear and tear.) In heading in this direction, Nikon is joining the aircraft and auto industries in moving away from metals to composites.
So, the bottom line is that with at least some of the higher end cameras, "plastic" isn't inferior to metal. In fact, it may be better: lighter,but just as strong as the magnesium alloys we all know, love and trust.
It looks like it's time for me to start reading the specs on new cameras with better informed eyes!