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
  • Jeff Allen

    The issue should not really be about mounting points these should be designed to take the weight and any leverage in mounting the lens onto the camera into question they are a structural component. The actual “mount” that attaches the lens to the camera if its subject to constant wear in this case a sliding compression wear should not adversely affect the focal depth. The wear can also affect the lock off point over time.
    Metal has long deemed to be better than plastic because its a traditional material with low wear in this application. Earlier plastics (nylon) could surface “tear” but thats not generally the case any longer as materials have improved dramatically since the 70s.
    In professional motion picture lenses metal is still used but mainly because these lenses tend to be heavier (and more expensive) and subject to more abuse. Weather sealing any lens completely is nigh impossible, but again professional lenses do a better job. What would be interesting is how metal Vs plastic lenses cope in very low and very high tempretures and how this affects focus.

  • Robert

    Thanks for the writeup, Roger.

    Do you carry any lenses with plastic bayonets?

    I buy and sell used lenses all the time, and I’ve seen LOTS of broken plastic bayonets, mostly on “kit” lenses.

    I would be curious to see what your statistics are on those items, if you have enough to be significant.

  • John Clow


    I think it would be wise if you consider either putting these pictures in your post or linking to them. This way there would be no confusion as to what you are talking about when you mention mount issues.

    Olympus Broken mount pics

    P.S. you are right 🙂

  • Anger management consultant :-)

    So will all these people who want metal “mounts” swear to never get on a Boeing 787? Look at how little metal is in it:

    Years ago, after a particularly frustrating conversation with DMV, I slammed my plastic telephone handset against the edge of a wooden desk. Typical Bell System “2500 set” against particle board with a formica veneer. I was fully trying to break the phone. I ended up putting a big dimple into the edge of my desk. The phone didn’t even show a scratch.

  • Roger Cicala

    Hi John,
    I wonder what country El Paso is really close to? I wonder how that small building I see at that address contains the capability to repair so many, many items that Precision repairs? I wonder why everything goes back to the East Coast to be remailed? I wonder about a lot of things.

    But you are correct: when Olympus closed their factory service they outsourced everything to Precision in, or near, El Paso. And don’t get me wrong: my hat’s off to Precision’s business model. They are one of the few rapidly growing, profitable repair companies.



    Olympus repair in the US is done in El Paso, TX at a place called Precision Camera. At least, in 2013. I sent 2 lenses and an EM5 in last year and service was prompt. The invoices listed replacement parts, so I don’t think they were refurbs sent back. The odd thing is they always send the item back to the east coast before sending it back, according to the tracking info.

  • My gripe with Olympus is that here in Israel they have only a distributor who ships P&S products to stores and has no clue about their more high-end stuff. So anything I use is purchased in the US and carried home. Nonetheless, I dropped a newish E-P5, shattering its LCD, brought it in to their main offices, improvised some paperwork, and sent it off to Portugal. It came back repaired (not replaced) at no cost, no shipping charges, in about a month, during a major holiday period.


  • Stan Burns

    I checked both my Canon and Nikon part lists. Canon calls what you refer to as a ‘bayonet’ as a ‘mount, lens’. Nikon refers to it as a ‘bayonet’.

    How’s that for confusion? Even the manufacturers can’t agree!

  • Reggie

    The plastic bit’s not surprising. People have lots of (mostly false) beliefs about the durability of plastics. That said, the weather sealing part is quite disappointing. I would love to see a breakdown of the truly weather-sealed cameras.

    Olympus users were always the most bold with their weather sealed equipment, but my old E-3/35-100 combo took on water when I was using it out on a lake once, from being splashed. I had thought maybe the seals on one or both might have just been worn out, but since Olympus service was going to charge a pretty penny just to tell me if there was really anything wrong with the sealing, and I was already migrating to Nikon, I didn’t bother. I am hoping to hit the snow with my D3s and a nice telephoto (probably one of yours) in Yellowstone soon, a guide on what combos have the best sealing would be great to see.

  • Roger Cicala

    Russell, it counts as an impressive video – and I’m a K3 owner personally and I do believe they have the best weather sealing.

    But the Pentax warranty on that camera says: This warranty does not cover any damage caused to the product, including, but not limited to: impact, moisture, liquid, . . . . So what it tells me is we’ll risk a few hundred bucks worth of camera and lens for some marketing, but we aren’t promising anyone anything and we sure aren’t risking having to repair a bunch of water damaged items.

    If Pentax was so certain wouldn’t they put their warranty where their mouth is? Once again, the manufacturer suggests something hoping the prospective buyer makes lots of assumptions, and the buyers do. Doesn’t cost them a dime.

    My whole point, not just here but throughout what I write, is let’s stop buying into all the BS they shovel at us. Because as long as we keep buying into it, they’ll keep on shoveling. They put a camera under water and didn’t make you one single promise. But you made assumptions.


  • Russell

    So does this count as to a manufacture telling you what weather sealing means?

  • Petr Jehlik

    Nicely done! Another very informative jet somewhat funny article 🙂
    I would like to know, how is standing Fuji with its X-mount lenses.. How about 14/2,8 23/1,4 35/1,4 60/2,4 etc – real metal mounts, or just metal bayonets?

    Thank you again and wish you all the best in 2014

    Petr Jehlik
    Czech Republic

  • Paul

    I enjoyed your article (like many other articles of you), but I just have to comment on this quote of you:

    “I understand that the terminology is inconsistent. Many people call the bayonet the mount, but it’s not the entire mount. The metal bayonet has 4 screws that connect it to the lens through the mount.”

    If that qualifies as mount, almost a whole lens qualifies as mount, because lots of parts are screwed or glued together and finally are connected to the bayonet.
    I’m Dutch, so my English isn’t that good, but doesn’t mount mean “link”? The link between a lens and a body is the mount, so the bayonet in case of the lenses discussed earlier.

  • Tim F

    That was an excellent review Roger! People need to get out and shoot more instead of wasting their time venting on forums… Nothing is accomplished time wise by doing so. Besides with all the choices in available equipment, It really is a good time to be a photographer!


  • Mike Banks

    Roger, thanks again for some great information. I have to tell you though, as a “professional” photographer, I don’t care if the lens has a metal mount or plastic mount. I’ve never been interested in most of the technical properties of my craft. Does it work? Does it make money for me? If so, I love it…if not I hate it. Pretty simple. Will it break down as compared to the usage an enthusiast uses his/her equipment, sure. I expect it to because it gets beaten up most of the time I out shooting.

    However having said all this I would still read everything you write in order to purchase the most durable equipment so I don’t have that many break downs. Please do a weather sealing testing and give us that information.

  • Wilt Wong

    Unfortunately ‘bayonet’ is NOT the right term simply because the long existant Asahi Pentax ‘M42 mount’ is not a ‘bayonet’, it is a SCREW in.

  • Wilt Wong

    Roger said, “…you are calling the mount what I refer to as the bayonet. Bayonet’s, with a very few exceptions are always metal.”

    Therein lies the source of confusion: The industy has been referring to ‘Canon mount’ vs. ‘Pentax mount’ vs. ‘Exakta mount’ (for ALL of my 45+ years in photography)to distinguish a lens as fitting Canon rather than fitting Nikon, etc.

  • Alexander

    About weather resistant and weather sealed. You should look at this video: Dave Dugdale asked a canon rep about it. Basically he told Dave: The moment you don’t want to be in the rain anymore, so does your camera/lens.

  • Mike Earussi

    Roger, thank you once again for an excellent and insightful article. Your unique access to volumes of repair and test data, via your business, enables you to present data no other tester can possibly match.

    I also second the request for a future article on which lenses/bodies are more weather sealed than others, as again, only you have access to enough data to make such an article meaningful.


  • Roger Cicala

    Thanks, Randy, that made me laugh. I went to a basketball game today with a neurosurgeon. He thought the professional neurosurgeon concept was incredibly funny – but did say he knew a couple of guys that he really thinks the term ‘amatuer neurosurgeon’ would be appropriate for.

  • Ed

    I often have to do minor repair on older manual focus lenses. Its pretty common for them to have plastic mounts as well. I’ve never seen one break, but have stripped a screw thread or two.

  • Mark

    Years back I dropped a new 1DsII onto a concrete sidewalk in Manhattan. I was sick when I saw it falling. The top by the hotshoe cracked, along with minor internal damage. $650 later, Canon returns it to me good as new, along with the cracked top as a keepsake. I was surprised when I saw the supposed weather sealing. It was merely little rubber gaskets that surrounded all the buttons on the underside of the top. So I’m not surprised at all to see the inside of the lenses.

    As for plastic vs metal, plastics have come a very long way and are incredibly strong.

  • Randy

    Thanks Roger. It seems Professional Quality Construction means about as much as professional photographer. But maybe that’s why there aren’t any “Professional” neurosurgeons.

  • Roger Cicala

    Eli, you should read the article before commenting. That’s a nice picture of the metal bayonet of the 24-70. The mount is just under that and is entirely plastic.

    I understand that the terminology is inconsistent. Many people call the bayonet the mount, but it’s not the entire mount. The metal bayonet has 4 screws that connect it to the lens through the mount.

    But if you’d taken the time to look at the pictures it should be really easy to see we aren’t talking about the load-bearing mount, not the metal bayonet.

  • Eli Velvel

    Mrs. Information: “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.”

    Plastic mount? Um, no. 35L? Plastic mount? Um no.

  • JJ G

    “And some (but not all) ‘weather sealed’ lenses also have internal gaskets around barrel joints and other added bits seals.”

    I appreciate the demystifying of the weather-sealing label and was wondering if you could do a more extensive post about it in the future. Specifically which lenses have the most or least seals while still being labeled as WR, and which lenses often come back with moisture damage, despite these WR labels. Obviously there are many variables, but it could still help photographers decide with more certainty if exposure to certain elements is relatively safe or not.

    Thanks for the always useful info!

  • NuclearPiper

    Roger, I agree that everyone is pretty much ignorant on lens construction, but you are taking a well-known idiom, “lens mount”, and redefining it to make it not include the bayonet. The bayonet and what is attaches to are collectively known as the lens mount. It’s a whole system, including the electronics, and not just a single piece.

    However, most people use “lens mount” to just mean the bayonet. So, don’t be surprised when people use the word as such. Instead of trying to redefine the term you should have come up with a new one, like “lens mount chassis” or “lens mount base” or something. Then we could all talk about it with much less confusion because you wouldn’t be fighting against our internalized definition of “lens mount”.

    What about lens mounts that don’t even have bayonets, like screw mounts? What do you call the threaded piece of metal on the lens? Everyone else calls it the “lens mount”. Semantics is a fun topic, and I could discuss it at length, but the short of it is this: if the vast majority of the population uses an term to mean one thing, and you use it to mean something else, you’re just going to cause confusion.

    You, yourself, don’t even use the term consistently in your article. Just look at all of your image captions. In each one you say that the screw holes are where the “lens mount” screws in. Even *you* are calling the bayonet the “lens mount” in every image caption.

  • John Andrade

    I think the complains about the mount quality of certain lenses was a confussion between the terms of “mount” and “bayonet” nobody doubt about the quality of the 35mm L, or the 17-40mm L that i personally have opened. Note that all those bayonets are metal. Very different of the 18-55mm or the 50mm f1.8

  • Roger Cicala

    John, that might well be the case. I will say they are improving the last 4 months or so, which is a good thing.

  • Rob

    [[There are lenses with plastic bayonets out there…I have two of them: A Canon EF 28-80 that was the kit lens on my Rebel 2000 film body, and a Canon EF-s 18-55 that was the kit lens on my Digital Rebel XT.]]

    We’ve followed the same path (photographically), I see, as I have both lenses and both cameras.

    All the 18-55mm EF-S (non-IS and IS) lenses have plastic bayonets. All the versions of the 55-250mm EF-S do as well. And the Canon 50mm f/1.8 II.

    I’d be willing to bet all the variations on those 28-(x)mm and 35-(x) kit lenses from the film days also have plastic bayonets.

    I don’t think the kit lenses are really “very few” or “very odd” but as a percentage of the Canon lens lineup they appear to be the exception.

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