Assumptions, Expectations, and Plastic Mounts

Published December 31, 2013

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 of the lens mount.


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 bayonet 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 bayonet 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 bayonet 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 it’s 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.


Tamron 24-70 f/2.8 VC. Another large lens easily and reliably supported on it's plastic internal mounts.
Lens mount with empty plastic holes that attach the bayonet, 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.


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”.

Roger Cicala and Aaron Closz

December, 2013

Author: Roger Cicala

I’m Roger and I am the founder of Hailed as one of the optic nerds here, I enjoy shooting collimated light through 30X microscope objectives in my spare time. When I do take real pictures I like using something different: a Medium format, or Pentax K1, or a Sony RX1R.

Posted in Equipment
  • No. You can wrap some big rubber bands around the outside where it mounts and that will help some.

  • Mueller

    Can I replace the mount on my Canon 80-200mm f/2.8L lens so that it’s weather sealed?

  • Andy

    I’m not a photographer, but a photographic retailer. I have to get my customers’ plastic mounts replaced every now and then, after a drop, and our main culprit seems to be Nikon 18-105mm lenses. The customers freak out when their lenses break away, but I love it, because it means an inexpensive repair, and that they haven’t bent the mount on their camera body.

  • Vlad Bieg

    Not a single comment since 2013?! We can’t have that! So, here it goes…
    …very interesting article, but it concentrates on durability and repair aspects ONLY. Taking apart lenses gives one unique experience and perspective, HOWEVER for vast majority of users all that is of marginal (if any at all) relevance. In contrast, VERY relevant question would be: is plastic mount machined with the same precision as metal mount? Within roughly the same manufacturing cost, is the same precision, assembly tolerances and alignment of optical components achievable with both (plastic and metal)? No insight in the article.

    Anecdotal evidence (so the number is just my guess): I believe that one in 10,000 users may be affected by a lens mount breaking or distorting due to impact or excessive force, at the same time all 10,000 users are continuously affected by how well a lens is manufactured, assembled, and what precision was achieved due to material selection. And please note: I am not saying “plastic bad, metal good”. Do your own research — I also never argue with people who claim absolute knowledge ;?)

  • Chris Nikander

    I just stupidly dropped my Nikon D200 + Nikkor 18-105 on the floor.Well the plastic bayonet broke. I was not happy off course, but it was better that the lens was damaged than the camera. A metal bayonet shurely would have been stronger, but maybe the camera would have been damaged.

    What about accepting plastic mounts, but have them easily interchangable?

  • Eric

    I love you guys ! 🙂
    Give us truth about lenses and body construction and reliability.

  • Peter Kelly

    Thanks Roger, That is what I’ll be doing.

    A right royal PITA and I wonder if it is this issue, rather than anything to do with the plastic, that has affected numbers of owners.

    Perhaps the Fotodiox mount is addressing a fairly minor possibility while all the time there is a bigger QC issue lurking…

  • Roger Cicala

    Peter, I’d send it back in to Sony. I know some people have had that issue and Sony has either fixed it or replaced their camera.

  • Peter Kelly

    I know this is a little late in the day, but I’ve just bought two Sony A7 and immediately became aware of the issue regarding their lens mount.

    If I remove the lens and press alternately on each side the mount will rock, on one almost to the degree of the silver disappearing behind the orange!

    Investigating further, I also came across your comments regarding the Fotodiox replacement on the DPReview site. In my case, the screws are certainly tight, but the problem is massive! I’d love to hear if you have any newer experience as to my best options.

  • An excellent article and some intelligent comments. Thank you.

  • Charles Morris

    I understand that mount is an internal construct, essentially the foundation of the lens structure. It has already been noted here that most consumers and a large number of pros (or self-proclaimed pros) will still argue that the bayonet is the mount. I used to work on cameras and lenses and do minor repairs, or more often it was more major cleanup than repair. The plastic bayonets on lenses worry me a bit and i have seen many of them damaged. In the last 20 or so years since i quit that business, the handful of “kit” lenses that had plastic bayonets has grown and I have finally learned to embrace these for what they are worth. that bayonet being made of plastic is a great compliment and even a safety feature for most of the all plastic camera bodies now. I can get a replacement bayonet for my 18-55 or 55-200 lens for less than $20 and it takes me about half an hour to clean off the table, dig out my tools and replace a mount where one of the lugs on the bayonet have cracked. I have done this for other people a dozen times in the last 8 years. In most of these cases i think the plastic bayonet saved the camera body and a couple times I have removed a bayonet only to find more damage and those i reassembled and returned to the owner with the suggestion to get a replacement or professional repair engaged. As much as people tout metal as being the only strong solution, i like plastic. in many cases it saves weight, in most cases it saves manufacturing cost, and only rarely do i regret the plastic in my lenses. I have a Nikon 18070mm kit lens i used for a very long time. it is quite literally worn out now and it is the plastic in the zoom mechanism is worn around the cams that carry the lens groups. So it is no longer possible to get a sharp image with it because at least one of the lens groups will be in the wrong place. I have retried this lens, I will miss it, but I can’t condemn it. That plastic allowed it to be a good companion at a low weight and a reasonable price for almost 9 years before i started to consistently notice focus issues.

  • Barry King

    I had been considering buying a ‘weather sealed’ lens for my Fuji X-T1, however I changed my mind and bought a quality rain cover instead, somewhat cheaper I might add!

  • Roger Cicala

    Vladislav, there’s some semantica that makes ‘mount’ confusing. As a repair person, I consider the ‘mount’ to be the place where the bayonet is attached to the main body of the lens – the part that supports the lens internally. Most photographers consider ‘mount’ to mean bayonet (the party you put into the camera and rotate 45 degrees). I can’t comment on a plastic bayonet because we didn’t look at that. We looked at the internal mount that attaches the bayonet to the rest of th lens.

  • Vladislav B

    Roger, excellent article, thank you. Unfortunately it does not tell the readers anything about the most important aspect Ramakant asked on April 5, 2014. Surely you have some insight into that – why no response? If indeed the plastic mount wears out faster if lens-swap is frequent, resulting in a less precise fit and deterioration of optics alignment, this would be something to worry about – not snapping the mount! I simply can not answer this question, but I think it is more important one, you should really expand on that.

  • Mel Snyder

    Roger, I think the problem is, many people don’t understand precisely what a “mount” is. They see a metal surface on the bayonet mechanism, and they assume that’s the whole mount. I can see from your disassembly that the “mount” is actually what the screws holding that bayonet plate attach to…and in many cases, even when the lens shell is metal, what’s underneath is plastic.

    “Plastic” is widely prefaced with the word “cheap” – and the implication is, “easily broken”…”unprofessional.” The Sony forum has many devotees who will be crushed to learn that under their metal-shell “Sony-Zeiss” lenses might be the same plastic as under a Sony kit zoom. They similarly believe the magnesium shell on an A7r somehow confers extra, professional impact resistance vs. the plastic shell on the A7. I would guess that the difference would be irrelevant if either camera was dropped 5 feet to concrete.

    Remember the furor when Canon introduced the plastic T90? Save for the bothersome EEE error, the camera works as well or better than the all-metal cameras of the error.

    I think we all need to get very real about what cameras are today vs. yesteryear, They are electronics boxes like our iPhones and iPads, and will be rendered obsolescent WAY before any plastic becomes an issue. My 1959 Nikon F would probably survive being used a lethal weapon. 55 years later, it is a wonderful working machine, as is my 1982 Leica M4P.

    But 30-50 years from now, no one will care that a Sony A7 or a Nikon D7100 or a Canon 5DMarkIII was built mostly of plastic…any more than they care about the construction of the 286 computer in a Goodwill dumpster.


  • Ramakant

    Dear Roger,
    Very nice write up about the practical aspects. I would love to know from you about one more bickering that I am told – that the plastic mount wears out faster if lens-swap is too frequent, resulting in a wobbly fit thus a) reducing the sharpness of photo-snaps and b) deteriorating the weather protection at the mount. Kindly elaborate your views!

  • Roger Cicala

    Marshall, I think your last sentence is a most excellent summary.


  • Marshall Goldberg

    I have been wondering about this. Pentax markets their DSLR’s as weather resistant. Does that mean they can withstand more abuse than a Canon 7D or 5Diii, or a comparable Nikon? Are construction techniques and materials used in the Pentax better than in the Canons and Nikons, or is Pentax merely marketing a feature which their competitors also have?

    I think there’s no way for a consumer to know without buying and deliberately damaging a few very expensive cameras.

  • Roger Cicala

    Peter, a very good point. I was thinking of the larger SLRs, but the AW1 certainly counts and is a game changer in that regard.

  • Peter

    You haven’t seen one lens manufacturer say what the lens is sealed against? What about the Nikon AW1 lenses? Nikon says they are sealed against water. Down to 49 feet. That seems pretty precise.

  • Frank

    Regarding the internal mount (the plastic load-bearing part with screw holes that the metal bayonet attaches to), and L glass Canon zooms – I actually think this might be done on purpose.

    When you drop a 1D class body with 16-35/2.8 attached (and trust me, for a working PJ such sh*t happens, especially in covering public unrest or similar high danger events) on concrete, usually the lens just separates nicely at that part, tearing away at the plastic rear tube, leaving you with a dented camera (but usually servicable) and lens with glass intact.

    Happened to me as well (well, I won’t go into details but I did manage to grab the broken lens before making a hasty getaway). The whole replacement was pretty simple – one flex wire, one plastic tube. I have seen several of these lenses fail in such “controlled” matter.

    I think it’s much more preferable to a ripped off camera mount and bented metal tube “permanent nonadjustable tilt/shit” lens…

    After all, if the lens rips apart at the plastic part, hopefuly most of the impact energy will be absorbed by shearing of the plastic part, just like a car’s deformation zone.

    That said, it obviously depends a lot on the design of the particular parts.

  • Christian

    I guess, that there is some sort of term-misunderstanding out there…
    Maybe this is not true for native English speaking guys but a bunch of people out there – although writing their blogs/webpages/whatever in Englich – whose native language is another one. Same is true for me.
    I have been into photo business for around 10 years now, work as a pro and do quite some reading about photography stuff. But – and I guess this is true for quite a lot of people like me – this article sort of opened my eyes… till now I took “bayonet” and “mount” as more or less identical terms when talking about a lens. I guess this would explain why many professional reviewers keep talking about “plastic mounts” when they actually mean “plastic bayonet”

  • Roger Cicala

    Ian, I really don’t with small lenses. In theory I could see where plastic might wear away over time with lens changes, leaving a loose mount, but in reality I haven’t seen it.

  • Ian Bullock

    Great article – but I would also be curious about your attitude towards plastic vs. metal bayonet, in your terminology. I’ve long wondered whether I should care about that or not. For example, many of the Samsung NX lenses are pretty solid optically but often have a plastic bayonet part. Is such a lens more likely to fail/have problems in general?

    In general, it makes sense that plastic could almost be better for some parts – it has some extra springiness to it that could absorb impacts more gracefully. And as you mentioned, if it fails, it’s more likely to act as a sort of “mechanical fuse” by breaking without exerting too much force on the surrounding parts.

  • Josh

    I would love to see a test where several different “pro grade” “weather sealed” lenses and bodies were left under a sprinkler or something for like 15 minuets or so and then immediately taken apart to see how much water actually got inside. I have a feeling many people would be in for a shock. Unfortunately such test is probably too expensive but it would be very interesting.

  • Water resistant??
    _5028005 copy
    I had to test it. You know, waving a red flag at a bull and all that – 10 minutes under a hot shower while powered on, sitting in about 1cm of standing water. All whilst intermittently shooting a frame or two, and no ill effects whatsoever afterwards. Impressive, to say the least.

    Go to

    Maybe this is the gold standard

    Keep the articles coming please

  • Roger Cicala


    I haven’t opened a lot of Fuji’s lately, but as best I recall most of them have internal metal mounts. The Touit’s are plastic.

  • Gary

    Gentlemen, I want to thank you for this write up on plastic lens mounts. I have a newly purchased Sony SLT-A58 and everyone speaks about the plastic lens mount on the camera, and of course, the kit lenses that come with it. But, so far, I haven’t seen any issues, nor do I expect to. Today’s polymers are well thought out, and yes, they can break, but it’s not too often. Only time will tell on my Sony, but thanks to your article, I feel justified in my purchase, or at least, easier of mind. Besides, the camera and the kit lens are lighter than my old KM 7D body alone. 🙂

  • Petr Jehlik ,Prague, CZ

    I will try it with my question once again and keep my fingers crossed.

    The question was – how about Fujinons for X-mount? ( And now I mean better built primes like 14/2,8 23/1,4 35/1,4 60/2,4M name it ) Are there internal metal mounts or plastic ones ? If I remember correctly, in some older post you call their (Fuji’s) mechanics “strange” but with no more explanation at all.

    And one more – how about Zeiss “Touit” lens family? ( As I understand from manufacturer’s commentary during launch – internal mechanic is made mostly (if not exclusively) from hi-grade plastics.)

    Thank you for reply.

  • Roger Cicala

    Robert, we really don’t carry many – almost by definition they’re too inexpensive to make rental useful.

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