Is Metal > Plastic? Not When It Comes To Lens Mounts, According To Lensrentals

Every once in a while Roger Cicala from Lensrentals debunks a myth. Today on his operating table is the Plastic vs. Metal lens mount myth.

Is Metal  Plastic? Not When It Comes To Lens Mounts, According To Lensrentals

Many photographers (me included) think that pro grade lenses are equipped with metal mounts rather than plastic ones. It makes perfect sense, right? Metal is stronger than plastic.

Well, according to Roger, we are all in the wrong.

As a person who takes lenses apart all day (every day) Roger is pretty informed about lenses, and while he does not provide accurate statistics, his rental house goes through hundreds of lenses of all kinda and types so his reports about what breaks and what is solid should be taken seriously. Roger tries to address some of the “facts” that popped up after the a few reports on the Olympus 12-40 breaking on the plastic mount.

His first interesting finding is that many lenses that the “internet considers” to be metal mounts are actually plastic mounts, including the Pro Canon 35mm f/1.4 L lens – a 15 years old lens and the Canon 24-70 f/2.8 L Mk I – which has a newer mkII model. This one carries over 2 pounds of glass off that plastic mount.

Canon 24-70 f/2.8 L Mk I. A professional lens released in 2002. It weighs about 2 pounds; far larger than any two micro 4/3 lens combined. It is generally referred to as a tank because it never breaks (it has optical problems, but those occur at the front end, which is, oddly enough, entirely made of metal). The plastic mount never breaks despite holding up 2 pounds of lens. Trust me on that, we’ve carried hundreds and hundreds of these for years and never had a mount break. (As an aside, the Mk II version has a metal mount, despite being lighter. I’m not sure why.)

His other interesting observation is that there is probably no connection between the material the mount is made of – metal or plastic to the likelihood that a lens will break.

The pictures show that for many years lots of very large, very high-quality, professional-grade lenses have had plastic internal mounts. Guess what? They didn’t all self destruct. In fact several of them are widely considered particularly rugged. Looking at 7 years worth of data involving around 20,000 lenses I can’t find any suggestion that plastic mount lenses, in general, fail more than metal mount lenses. Sure, there are certain lenses that fail more than others, but not because they have a plastic mount.

In theory, plastic mounts might be better, worse, or no different than metal as far as reliability goes. There are logical arguments for each.

The post goes on to debunk another myth about weather resistant lenses – you’ll be surprised what it means.

[Assumptions, Expectations, and Plastic Mounts | Roger Cicala and Aaron Closz]

  • Fouda

    That’s why I like stress-tests to verify extent of “weather sealing” claims, like The Phoblographer does by operating a weather sealed body+lens under a running sink-tap, making sure to turn & flip all the knobs & features the camera could do

  • creamofmeat

    I don’t like that when you constantly take off and reinstall plastic mount lenses it wears away the plastic, making the mount loose and introducing more dust inside the camera. As for sturdiness, the metal lens mount is usually screwed into plastic anyway.

  • Bloke

    Camera companies tend to refer to the lens mount as the part that touches the mount on the camera, not the internal design of the lens itself. Is also worth mentioning that the plastic involved in many Canon lenses is impregnated with a type of carbon fibre, which significantly improves rigidity. Typical examples of a plastic lens mount, I can think of would be the Canon 50mm F1.8 versus the Canon 50mm F1.4, Which has a metal mount.

  • Charles O. Slavens

    Yeah… well this has been my experience; plastic mount lenses are great as long as you don’t drop them… with or without the camera attached. If you’ve been using your camera for years in fast-paced situations, or if you just shoot table top and have a clumsy assistant, you’re better off with metal mounts.

  • Wil Fry

    It doesn’t make any difference to me. If I drop a lens out of a second-story window onto concrete, the mount probably doesn’t matter. I don’t plan to drop any of them from any height, so the mount could be made of just nearly anything.

    Kind of like the “pro” bodies with more robust frames, compared to the Rebel-level bodies with less metal. It doesn’t matter in most instances. All of them will stand up to a little abuse. None of them will stand up to terrific abuse (run over by tank, shot by rifle, etc.). It’s the “kind of rough” middle ground that makes a difference for some people.

    Personally, I can’t afford to replace any gear, so I treat all of it gingerly, like I would Fabergé.