Assumptions, Expectations, and Plastic Mounts

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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

116 Responses to “Assumptions, Expectations, and Plastic Mounts”

John Krumm said:

Great article, just love it.

About Olympus repair, I know your stats show them to be exceptionally slow. What's strange is that so many of us Oly users in the various forums have not found that to be the case. I've sent in three repairs, two lenses and a body, and all were speedy. My last aperture fix a couple months ago took 3 days before they sent the lens back. The only thing that slowed it down was the cheaper UPS return shipping they used. Almost makes me wonder if they are putting commercial outfits like yours on the back burner.

LensRentals Employee

Roger Cicala said:


Remember earlier this year there was a 6 weeks period where there was no Olympus service department. It just closed and you couldn't find out a thing about any gear they had. And there were lots of people freaking out: no one answered the phone or emails, etc. That's way past unacceptable. So what happened many years ago has nothing today with Olympus today.

But I do applaud what they did with your new camera, and they are improving lately. Olympus seems to be taking a page from Sony: cameras and electronics are often replaced by a refurb or replacement quickly instead of repaired. But actual repairs, particularly with lenses, go out of the country to be fixed by a subcontractor, then returned. That's usually a 30-45 day spin, easily the longest in the industry currently.


Dan said:

In your earlier response to a poster, you referenced poor Olympus service in the US. I've had the opposite experience. I sent my E-M5 in for service, because of exposure problems, and Olympus sent me a new one. Total round trip time was less than 10 days. I broke the shutter button off an E-PL5 and sent it to Olympus for repair and had it back within a week. Many years ago, I had an OM-2 that failed and I happened to be traveling near an Olympus repair center. I went it; showed it to them and told them I was on a trip. They went in the back, got a new one and handed it to me. I've had nothing but excellent experience with their US repair service.

LensRentals Employee

Roger Cicala said:

KhunPapa - you are calling the mount what I refer to as the bayonet. Bayonet's, with a very few exceptions are always metal. What they mount to inside of the lens is the lens mount. It can be either plastic or metal and is the part in question here.

LensRentals Employee

Roger Cicala said:

KhunPapa - I agree. Never assume.

The Panasonic 25 f/1.4, 14 f/2.5 and 45 f/1.8 are entirely mounted into plastic. The Panasonic 35-100 is also mounted into plastic, but there are thin metal sleeves inside of the plastic mount. The sleeves aren't load-bearing, though, they simply are to receive the screws that hold the bayonet on.

Not sure where you got your information, but it sure wasn't from taking the lenses apart and looking. It is incorrect.


KhunPapa said:

Third : Plastic mount is plastic mount.

It's not the same as those darn plastic screw holes which are subjected to shearing force or impact.

In the 12-40 owners' photos, or your shown photos, you'll see the broken plastic holes/screw. None the mount.

Even the mount were made from paper card board, when there's impact, it will damage - none. The impact force will be transmitted to the screws and holes, cutting or ripping them out.

Olympus E-3 famous "separated LCD screen" is the clear cut evidence of the shameless Olympus Engineer's design. Period.

KhunPapa said:

Second: You are right.

Weather Seal is NOT water resistant.
Water Resistant is NOT water proof.

The sealed metal ball is water proof and water resitant.

The diver's wristwatch, underwater-class digital compact camera, or SUBMARINE, is water resistant, UP TO THE SPECIFIED PRESSURE. But it's NOT water proof.

Weather-resistant camera is just that - weather-resistant. No more.

There is NO single word in the official manual of E-M1 or E-M5 which states that the camera is water-proof nor water-resistant.

In fact, the OFFICIAL manual even warn the owner that he/she must not leave the camera for a long time in the humind environment.

BUT, seem like no one reads that manual.

KhunPapa said:

"Most micro 4/3 lenses have metal mounts (they don’t – only one does that I recall)."

Panasonic 25mm f/1.4
Panasonic 14mm f/2.5
Panasonic 35-100mm f/2.8
Olympus 45mm f/1.8

Never Ass-u-me :(

LensRentals Employee

Roger Cicala said:

Bob, I certainly am not trying to say disappointment about the lens is unjustified. As I said in the article it may have a design flaw, there may be a bad batch of mounts, lots of things. I simply wanted to discount the very silly people who stated with absolute certainty that "any professional lens should have a metal mount" and "using plastic in the mount is something for just kit lenses". As is usually the case, when people overstate their case and say they know ridiculous things "with absolute certainty" they just end up looking silly.

But I've heard different versions of the Olympus statement. If they just said it's a metallic lens, I think that's probably OK. If they said "All metal construction", then I agree, they are lying. But truth is I think "weather sealing" and "Professional grade" are pretty much lying, too. A bit grayer, perhaps, but lying nonetheless.

Do I like the design? I don't have an opinion, really. It's too early. Let's see how it does over a year or two. Is something wrong with the lens as released? Probably, but it may be fixed with something as simple as a longer screw with coarser thread.

Having been in this game a long time, I've gotten to expect the "early adapter is our beta tester" reality. Whether it's D800 or 1D Mk III autofocus, D600 dust, flashes that burn out, or IS units that fail. If you wait in line to be the first one to get a brand new product, you're taking a risk. It may be wrong that it's that way, but it's reality.

As an aside, when people really want something to scream about with Olympus, the repair service (well actually their lack of one in the U. S.) is a better place to start than their lens design. But it sounds like they're fixing the problem at no charge (in their usual 45 days or so), which is the right thing to do.

Ian Anderson said:

Roger, the weather sealing "exposé" is epic! I'm not shocked, but it makes the 5DIII light leak taping seem pretty sophisticated!

Dan said:

Interesting article, and I agree that the word "professional" doesn't imply the type of material the product is made from. However, what I think has people upset is that, in this case, their lens broke quite easily without having been abused. Panasonic's 12-35 f/2.8 has been around much longer, with many more in the field, and there have been no reports (at least none that I've seen), or ravings about it breaking from simply bumping the camera or case, with the camera in it. So, while people are certainly reading more into "professional" than should be implied by the word (to me it would imply higher IQ, but not that you can pound nails with the product), there may in fact be some design problem with this particular lens. This is especially of concern since the lens hasn't been around very long and the numbers in circulation are much smaller than other m4/3 lenses.

Bob said:

Roger, I don't think that the issue is really whether the lens mountings are metal or plastic. The issue is a breech of faith. Olympus claimed this lens to be of "all-metallic construction." Now maybe "metallic" is a weasel word, as opposed to "metal," but the intended interpretation by consumers is clear.

Olympus lied. THAT's what upsets people more than the use of plastic, I think. That, plus the fact that at least 3 samples have broken in exactly the same place. Plastic, properly engineered, is fine. There is a legitimate question whether this lens is properly engineered. There is no question that Olympus misled buyers.

You've done a fine job of proving your straw-man argument wrong, but not in proving that the disappointment over this lens is unjustified.

Steve P said:

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.

On the Rebel 2000, the part that mates to the lens bayonet is also plastic. On the XT, that part is metal.

Stefan said:


I am one of the guys who who had the misfortune of getting a lemon when I bought the EM-1 kit with the 12 - 40 lens. I was so disappointed with the lens since it broke in my camerabag when I was out walking. I really love the optical qualities of the lens and I really want a sample I can trust. I don't really care what the material in the lens is if it just works. Your fine article is getting my hopes up again. I left my lens with the shop and they sent it to Olympus in the first week of december. I got a preliminary date for the return of the lens at around the end of january or early february due to christmas, seems they need a tad more than 15 minutes for repair. It will be interesting to hear what the verdict will be. Also, the camera performs greatly and is hands down the most pleasing camera to shoot with that I have owned. Again, great article!



Goblin said:

Roger, thanks again for yet another interesting article.

For what it's worth - speaking of weathersealing - After a full day of shooting at a water park under splashes and flushes with my E-M5 + 12-50mm Zuiko lens setup, I still managed to drop it in a 3ft pool. It spent seven or eight seconds under water before I managed to retrieve it.

The camera took water in the memory card bay as well as the battery bay. It came gradually back to life after a few days in a bag full of rice. While it obviously took water, it didn't take water at the mount, and the whole sensor area remained unaffected. It works great to this day.

As for the lens, which is the main reason I am mentioning this story at all - I simply wiped it, took it off, put it on my spare G3 and it went on running like if nothing happened. Just as the camera, it works fine to this day.

The 12-50mm must be to this day the most snobbed and disdained m43 lens, but it's certainly not the least protected.

Paul said:

I'd love to know what is inside the Fuji lens Roger. Any idea in general? Given that you see so many lens in general, it would be very helpful to see your subjective assesment (coupled with your rough data of repairs) for different lenses! :)

Matthias Welwarsky said:

Concerning the Tamron 24-70/2.8, the "mount" is certainly not the weak spot of this lens. I had one break in the bag while mounted on the camera and the mount held, but the lens nevertheless cracked open at the seam next to the focus ring. OK the bag fell down. OK, ok, it fell out from a baggage compartment in an overland bus. OK, the baggage compartment was right under the ceiling of the bus and you had to stretch quite a bit to put stuff inside :-)

I think it was plain bad luck, anyway. But now I'm treating it like a raw egg :-)

Doug said:

Great article Roger. I just rented an EM1 and the 12-40 from you for a week and enjoyed it very much, without incident. :)

You make a great, and obviously well informed point re: plastic vs metal.

But people jumping to the conclusion that the plastic is to blame for Oly 12-40 breakage is probably just frightened consumers wanting to find a reason for the reports. I'm glad to hear that you have not seen any issues with your stock of the 12-40. That would support the theory that there was a brief manufacturing problem or that a few of the components were faulty, but that the design is sound. As you point out, the components (plastic) are not the issue in general. Not knowing how many lenses were sold and delivered makes it hard to call this a trend, but wouldn't you agree that the number is probably still relatively small (at least compared to other established favorites) and that the number of reported breakages is somewhat alarming? I have to admit, I was very keen to buy one (especially after spending a week with it), but have delayed purchase for a bit. Maybe I'll just rent it again soon! :)

Joachim / CH said:

So, there IS a difference between "mount" and "bayonet"? Just asking as non-native speaker and because I see the term "mount" in combinations like "Nikon mount", "Canon mount" - at least Zeiss calls their adaption to one of these brands "mount". I wonder how much people would make a difference between mount and bayonet?

Speaking of Zeiss (not Sony-Zeiss): It's quite easy to use more metal than plastics for their photographic lens, if
there's no electric driven aperture
AF-drive and distance information for the camera
Integrated anti-vibration system
because all these features use integrated circuits and are powered electrically - therefore need to be insulated against shortening. So, making an "all metal (not metallic - plastics can be metalized) construction" would increase the weight, make fast AF nearly impossible and would still need plastic parts for insulation

There are plastics which cost much more than metal per weight unit. But still, the general term "plastic" indicates cheap, easy-to-break, low value parts. While "metal" stands for higher value and longer usage. Rubbish. But very easy to be put into marketing blah and so effortless to believe.

Ed said:

I am one of those that have experienced a broken mount with the Olympus 12-40mm. I sent the lens back to Olympus USA for repair. Like you said, it was a quick fix and did not cost much to get it repaired. The circumstances surrounding my accident was that amera/lens got knocked off a table and hit a carpeted floor. As I think about it, had the mount not broken away there would probably have been more substantial damage to both the lens and the camera. As it stands, only the lens mount was damaged. The camera body (E-M5) sustained no damage whatsoever.

MarcG19 said:

Thanks, Roger! Very informative article and discussion.

Berni said:

Hi Roger

Thank you for taking the time to write the article. I always really enjoy reading your work. Informative and interesting. Well done.


LensRentals Employee

Roger Cicala said:

Markus, I don't know - I simply don't know enough about stress engineering to say one way or another. But some lenses do seem to have a stress plate of plastic between the metal of the bayonet and a largely metal lens. It may be shock absorbing, a breaking point, or simply economics.

Markus said:

Roger, do you have the feeling (or experience) that some lenses may actually have been designed having a "breaking point" to keep away damage from the camera?

amin said:

thanks roger & aaron
your articles are best!

Timur Born said:

Thanks for the article, Roger!

Two things to mention here:

1) Regardless of supposedly mount issues some people were specifically not enamored by Olympus US site's wording (claim) of "all metallic construction" when most of the lens is made of plastics. One might call it a catchphrase, but one might also call it lying. ;)

2) Olympus' Toshi Terada explicitly claimed that you can still zoom the 12-40/2.8 when the zoom barrel is wet (by rain) without sucking in the moisture. He pointed to Olympus' long experience with lens sealing from the FT line and funnily he also knew (and called crazy) that one Youtube video where someone dips a E-5 in hot brine water and then washes it off under the shower. So while Olympus don't stand behind their sealing with a proper specification some of their folks and seemingly lots of users do trust their lenses quite a lot.

By the way, the catchphrase "cold resistant" of course doesn't mean that the lens/body do keep out "cold". According to Mr. Terada it means that they asked their engineers and suppliers to supply parts that can operate down to -10°C temps. When you think about it then this is the preferable way of doing it. ;)

Scott said:

"metal" and "plastic" are very generic terms. Unfortunately those on forums like to deal in absolutes. What needs to be evaluated are the properties of the actual material to be used. There absolutely can be a "plastic" material that has superior properties for the intended use over a "metal" material. This all part of engineering, selecting the material that has the combination of properties AND cost for the particular application.

Unfortunately this is lost on the dolts on the forums.

Paul said:

Brilliant information. Love this site's pure fact-based articles.

Longtime photo enthusiast (since I was a kid who worked all summer long to buy a Canon A-1 film SLR) with little money to spend on photo equipment these days, sadly. But when that changes I will be all the better informed in my choices thanks to lensrentals.

Ben said:

I broke my 24-70 mkI at the mount if that helps. I may have slightly dropped it about 4 feet onto the ground while attached to the camera if I'm being honest :)

John said:

"The truth is, terms like Professional Grade and Weather Resistant are nearly as vague as ‘innovative technology’ and ‘stylish design’."

Perhaps this is one of the few exceptions, although speaking of camera, not lens ...
Extract from Camera specifications manual ...

Olympus OMD-EM1 ...
Splash resistance ... Type Equivalent to IEC Standard publication 529 IPX1 (under OLYMPUS test conditions)

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