Are Metal Mounts Any Better than Plastic? LensRentals Investigates


Photography companies love catchword marketing. They like catchwords because photographers make assumptions about what those words mean, even though the words really don’t mean anything. So basically, they say nothing, but it makes you believe something.

Two of my favorite examples are “professional quality construction” and “weather resistance”. When I read those terms, my brain translates them to “Blah, blah, blah. Blah, blah.” They are subjective terms, just like ‘elegant design’ and ‘innovative styling.’

Most photographers, though, make all kinds of assumptions about what those catchwords mean, and have all kinds of expectations about the equipment that is described by these largely meaningless bits of marketing. We all know what Oscar Wilde said the word assume really means. Expectations, of course, are simply a down payment on future disappointment.

I have watched several world-class internet meltdowns with great amusement recently. All were started when photographers found out that their assumptions and expectations about what catchwords meant were wrong. They became a firestorm when people added a lot of ‘facts’ that weren’t really facts.

Plastic Mounts and Professional Construction

Much of the recent internet rioting was triggered by some Olympus 12-40 lenses that broke off at the plastic mount (the mount is the internal part of the lens where the bayonet — the metal part that twists into the camera — attaches by several screws). Several people reported their lenses broke at the mount with minimal force applied (a short fall or even pressure from other items in a camera bag). We ship those lenses all over the country and they seem no more likely to break than any other lens we stock. But apparently at least some of them had a weak mount.

What amused me was the absolute fury expressed by numerous photographers that a “professional quality” lens might have a plastic mount. I’ve looked up the term ‘professional quality’ everywhere and nowhere have I found it defined as ‘having an all-metal mount’. But some people are livid that it isn’t so. If you’ve read one of these posts on the internet lately, you’ve learned all kinds of things … none of which are true.

  • Most micro 4/3 lenses have metal mounts (they don’t – only one does that I recall).
  • All ‘professional quality’ lenses have metal mounts (they don’t, not even close to all do).
  • Micro 4/3 lenses and NEX lenses all have plastic mounts, but ‘real’ SLR lenses have metal mounts (not true on either side of the comma).
  • Plastic mounts are only used on cheap kit lenses and have only appeared in the last few years (They’ve been around for a long time on many lenses).
  • Lenses with plastic mounts break more frequently than lenses with metal mounts (Nothing suggests this).

I take apart lenses all day every day, so I was rather amazed to find all these facts spoken so dogmatically by people who claimed them to be absolutely true. I make it a rule never to argue with people who claim absolute knowledge, no matter how wrong they are. But I will occasionally show them pictures. So here are some pictures of the mounts of lenses that Aaron and I took apart for various reasons this morning.

Canon 35mm f/1.4 L lens. Released in 1998 (15 years ago), considered a Professional Quality lens, and certainly carrying a professional quality price. It has a plastic mount. In fact, we keep that mount as a stock part because we have to replace it every once in a while. It doesn’t break often, but we have hundreds of them and they do break once in a while.

Canon 35mm f/1.4 L with rear barrel removed, showing 4 plastic posts that the lens mount attaches to.

Canon 35mm f/1.4 L with rear barrel removed, showing 4 plastic posts that the lens mount attaches to.

Panasonic-Leica 45mm Macro Elmarit f/2.8 m4/3 lens. I won’t argue about whether it’s a Professional lens, but it’s really good, really reliable, and quite expensive. It has a plastic mount despite online claims otherwise.

Panasonic-Leica 45mm. The 4 empty plastic holes are where the lens mount attaches. The 3 screws still in place attach this plastic piece to the next plastic piece in the lens barrel.

Panasonic-Leica 45mm. The 4 empty plastic holes are where the lens mount attaches. The 3 screws still in place attach this plastic piece to the next plastic piece in the lens barrel.

Sony 50mm f/1.8 NEX lens. Again, I’m not arguing Professional here, but this one is widely mentioned in the forums as ‘all-metal construction’. It has a metal shell, just like the Olympus 12-40mm, but the support pieces are plastic and the mount screws into plastic, just like the Olympus 12-40mm.

Sony 50mm f/1.8. The 4 hollow plastic posts are where the screws from the lens mount attach.

Sony 50mm f/1.8. The 4 hollow plastic posts are where the screws from the lens mount attach.

Canon 14mm f/2.8 Mk II L. I don’t think anyone argues this is a Professional Quality lens at a very professional cost. An ultra-reliable lens, but it certainly has a plastic mount. Not that we ever have to replace them. They never break here despite being far larger than the Olympus 12-40mm.

Canon 14mm f/2.8 II rear barrel showing hollow screw hole in polycarbonate inner barrel where the lens mount attaches.

Canon 14mm f/2.8 II rear barrel showing hollow screw hole in polycarbonate inner barrel where the lens mount attaches.

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.)

Canon 24-70 f/2.8 Mk I. That big beast is easily and reliably supported on its 4 polycarbonate screw mounts.

Canon 24-70 f/2.8 Mk I. That big beast is easily and reliably supported on its 4 polycarbonate screw mounts.

The Tamron 24-70 f/2.8 VC lens. I include this one just for completeness, because it’s another large lens and at least one online authority has stated it has a metal mount. Sorry, there’s no metal back there at all.

Common mount with empty plastic holes that attach the lens mount, and screws remaining in holes attaching this to the next barrel piece.

Common mount with empty plastic holes that attach the lens mount, and screws remaining in holes attaching this to the next barrel piece.

Attention Fanboys: Just because your favorite lens isn’t shown here doesn’t mean it doesn’t have plastic mounts. Lenses of 70-200 f/2.8 size and up all have metal internal mounts (as best I can recall), but lenses smaller than that may be either metal or plastic. All Zeiss ZE and ZF SLR lenses have metal internal mounts (but not Zeiss-designed lenses for other brands). Nikons are more likely to have metal mounts than other brands, but they have a fair amount of plastic-mount lenses, too. Otherwise, the majority of lenses have internal plastic mounts.

Does it make any difference? I looked at the Lensrentals’ reliability data for the last several years (several thousand repairs), and there’s no higher failure rate with plastic mount lenses. They have, if anything, a bit lower failure rate, but it’s not a significant difference.

When a plastic mount does break, people tend to freak out a bit because the lens is so obviously broken. From a repair standpoint, though, we love them. It takes 15 minutes to replace a broken plastic mount and the lens is as good as new. Metal mount lenses don’t break like that. Instead internal components and lens elements get shifted and bent. It can take several hours to return one of those to optical alignment.

So What Does It Mean?

Absolutely nothing except that internet hysteria is alive and well. By my latest count, during the last two weeks 7,216 internet experts have claimed it is an absolute fact that plastic internal mounts are a new, cheap, poor quality substitute for internal metal mounts. The pictures above suggest otherwise.

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.

Obviously a few Olympus 12-40mm lenses have broken at the mount. It may be there was a batch of badly molded mounts. It may be a design flaw. It may just be random chance – a few of everything break. But it’s not just because the mount is plastic.

I do like taking this opportunity to remind everyone that marketing catchwords like ‘Professional Grade’ mean very little. If they say it has 16 megapixels they’ve told you a fact. If they say ’Professional Grade’ that’s a word with no clear definition. It probably means ‘built better than some of our cheap stuff’.

Speaking of Catchwords

As long as we’re on the subject of catchwords, it’s probably worth tackling ‘Weather Sealed’ or ‘Weather Resistant’ next. Many people seem to believe that means ‘waterproof’. When you take lenses apart all day you find out it usually means ‘we put a strip of foam rubber behind the front and rear elements and scotch tape over the access holes under the rubber rings.’

Strip of foamed rubber that sits behind the front element of a ‘weather sealed’ lens.

Strip of foamed rubber that sits behind the front element of a ‘weather sealed’ lens.

Tape over access holes in a weather sealed lens.

Tape over access holes in a weather sealed lens.

It’s better than no weather sealing, certainly. And some (but not all) ‘weather sealed’ lenses also have internal gaskets around barrel joints and other added bits seals. But I haven’t seen one manufacturer yet tell us exactly what weather their lens is sealed against. Snow? Rain? Sunshine? Wind? Well, it can’t be wind because the lenses we spend the most time taking dust out of are mostly ‘weather sealed’.

It’s very different with different manufacturers. You can assume whatever you like, but when you send your lens in for repair, ‘weather sealed’ still means ‘the warranty doesn’t cover water damage’.

The truth is, terms like Professional Grade and Weather Resistant are nearly as vague as ‘innovative technology’ and ‘stylish design’. I’m certain it’s only a matter of time before I see an online post that says, “I bought this camera because the manufacturer said it had stylish design, but it’s butt-ugly. I think we should start a class-action lawsuit for false advertising.”

About the Author: Roger Cicala is the founder of LensRentals. This article was originally published here.

  • slvrscoobie

    And for sure, my 14mm Rokinon handled the ocean wave that washed over it at the beach a lot better than my ‘weather sealed’ 5DIII. A night of rice and the 14 was and still is in perfect working order even after taking a wave to the front element. the 5DIII cost me $500 at canon With a CPS discount – but it is still working well now..

  • Joey A

    Hear hear! Finally someone’s speaking out about this. I doubt it’ll change anything though — people want to spend money, and need a reason to spend more. Wether it’s a BS reason or not makes no difference.

  • Steve Oakley

    you know no one is talking about the quality of plastic, polycarbonate, hi tech polymer or CF. my rokinon cine 14mm has a metal mount attached to plastic internals. guess what ? one drop to the floor when mounted on camera and the plastic right behind the metal mount snapped off. looked like simple repair – replace the plastic part held in by 4 screws + lens mount screws. However, no parts available for sale for DIY or at NY “service” center. Had to replace it. They did cut me a very fair price to do that… but I was expecting $10-$20 part + 1/2hr of labor…

  • araczynski

    nice read, its neat to read a piece by someone who has real practical knowledge on the subject due to being knee deep in it every day. i could dispel a myth or two about the perceived mac computer superiority due to having to deal with them and windows machines all the time as well. anywho, you’re right, marketing fluff is just that, B.S.

  • 4545454545

    i take a 500mm f4 with plastic mount for 7000 euro al day over a 500mm f4 with metal mount for 10000 euro….

  • JONjon

    who cares?

  • affr

    Love this. Thanks for sharing your ideal/realistic inside view on this. I’ve often been swayed by metal vs plastic mounts.

  • Guest

    Clarification: The Nikon professional series lenses are all steel/brass metal mounts. The DX kit lenses have plastic mounts but are clearly engineered for a shorter product lifecycle so metal would probably be over-engineering.

    Clarification 2: I’ll quibble with the “Metal mount lenses don’t break like that” paragraph because, obviously, by the time you have bent or broken the metal connector, it’s been trough a lot more.

    Note: I know some fellows who refuse to by Pentax lenses for trade in at their camera shops because apparently this group of owners has gotten it into their heads their lenses have magical properties for resisting water.

  • steve-0

    The discussions are usually based on how well a lens fits on a camera because the flange distance is usually really accurate.
    Plastic lens bayonets are easier to give a little bit in opposed to metal bayonets.

  • leo

    The article is talking about the mount underneath the metal (what the metal attaches to)

  • AE

    I may be wrong, but I always though the plastic mount provided a built in fail point. A little while ago I was photographing a cycle race. Unfortunately I got a bit too close and a bike hit my lens (thankfully no one was hurt in this!). The lens flew off the body leaving just the mount. At first I was horrified, but quickly realised what a great design it was, because it saved any damage to the body.

  • madmax

    Great, Roger. You are a real “mythbuster”!

  • zaakir

    problem is most good lenses are as much if not MORE than the body. *shrug

  • zaakir

    no need to be a dick, thanks

  • hdc77494

    Roger makes a great point here worth highlighting. While plastic mounts are apparently no more prone to breakage than metal mounts, when the plastic fails, it does a lot less damage to the overall lens and is faster and cheaper to repair. Built like a tank sounds great, until you have to rebuild the tank…

  • hdc77494

    i believe that was his point. the plastic broke in the collision leaving the lens repairable and the camera intact rather than an expensive paperweight.

  • Conner Werty

    Which lens had the scotch tape “weather sealing’?

  • Zos Xavius

    Hard to say. I’d love to know too! It had a grey plastic barrel, so maybe not pentax? I’ve seen how pentax weather seals their lenses and its not bad, but interesting that the sealing traps more dust. not what I would expect. None of my lenses are sealed personally and I shoot in the rain often. With old primes and a good hood its not a big deal at all. I wouldn’t dunk it under a faucet like that though.

  • Nate Parker

    I do mostly seascapes and my old 5DII has taken more than one wave A-Ok, maybe the water got in at the mount?

  • chris

    Roger can you tell us which lenses actually had these insufficient weather sealing gaskets/scotch tape?

    Thanks in advance
    Keep on your amazing work!

  • Nicolaie

    Keep using that word, mount. I don’t think it means what the internet thinks it means. I certainly think at the lens mount as the part that actually mounts in the camera, not the internals that hold the part that mounts in the camera.

  • Andy Umbo

    My Nikon 18-105 has been in twice, all because of plastic mount “flex”. This causes the camera to get error reading and refuse to work; then you have to unseat and reseat the lens, sometimes that works without taking the whole thing off. I’ve been around enough to know that precision plastics and carbonates can certainly be a match for metal and maybe even exceed them in certain uses, but this is just bad design….

  • Tore Hansen

    Thanks for confirming what I have known for years.

  • wickerprints

    That’s because the lens is mostly plastic, and elements are secured with adhesive in addition to retaining rings. There are no internal electronics to corrode. As for the 5D3, no electronic device will survive corrosion through exposure to salt and moisture, and “weather sealing” does not mean “impervious to seawater.” It’s your own fault for taking a precision electronic device into an environment without an appropriate housing. Don’t try to put that on Canon. Last time I checked, getting splashed by ocean waves is not considered weather, unless you’re inquiring about the surf report.

  • Michael D

    I suspect that’s wrong. The vulnerable spot is probably the spring that holds the camera and lens flanges together, and that’s likely weaker than either of them.

  • Roger Cicala

    The one in the picture is a Canon 70-200 f/2.8 IS II, but most 70-200s have some scotch tape over the access holes in the zoom and focus rings. It actually works very well, but I find it kind of amusing.

  • jrconner

    No surprise here. Plastic is a lot stronger than many suppose. I have two Nikkor zooms with reinforced polymer mounts, one since 2005, and both have been trouble-free. We now have airliners made mostly of plastic, so it should be no surprise that plastic is a robust material for lenses.

  • cacamilis

    My Pentax K5 and Sony a77 are both weather sealed but I wouldn’t bring the Sony out in a downpour, that’s how much of a difference there is

  • Mali John

    I just bought an Olympus 40-150mm lens yesterday. I am in the Philippines. I had it shipped to my nephew in Santa Clara, CA. Just a while ago, he told me the lens is too placticky and even the mount is plastic. He said he won’t use it for fear of breaking it. So, I kinda panicked and thought of returning it. Thanks a lot for this article my fears were quelled.

  • catfish252

    You are just the type of individual that Roger is speaking of, Nikon does not market or claim to have a ‘Professional Series of Lenses’

  • Lou Franco

    I found this article while searching for “plastic vs metal mount on lenses” and am really glad I read it. Thank you for writing a “real world” article on this!