Are Metal Mounts Better Than Plastic?

[mrsfotografie]

I think Rogers's definition of a plastic vs. a metal mount differs from how most people think about those terms.  For most of us, we're talking about the bayonet parts - the 'teeth' that lock into the mount on the camera. 

 

The EF-S 18-55 on the left has a 'plastic mount', the EF 17-40L on the right has a 'metal mount'.  Very few of us disassemble lenses, so we have no idea what's behind that mount surface.  Roger is talking about how the screws that that attach that visible surface piece to the lens are connected - do those screws go into metal screw-holes that are attached to the frame of the lens, or are the screw-holes plastic?

'Plastic' can be quite strong, so for a 'light' lens (most lenses under 100mm, with the exception of the 'magic cannonball' 85L), I agree with Roger that I wouldn't expect any issues, and 'professional' could apply.  However, for the bayonet 'teeth' of the mount, plastic wears down more easily than metal (vs. the screw-holes, which aren't subjected to routine 'wear'). That means a lens with a plastic mount (as I'd say is the common definition pictured above, not Rogers's use of the term), would be able to tolerate fewer mount/unmount cycles than a lens with metal bayonet teeth.  Since a professional lens would be expected to last years and most 'pros' own several lenses and change them frequently, it makes sense to associate a metal mount (as pictured above, regardless of how it's screwed in) with 'professional' build.

+1, I couldn't agree more. Besides, engineering plastics really are tough, and in some applications even more suitable than metal.

[Lee Jay]

Weather sealing means a little bit splash proof.

You know what "water proof" means?  Take a look at the manual for the Canon 10x42L binoculars.  In the manual it says that if the outside gets covered in salt spray, or sand or whatever, that you should soak the binoculars in a bucket of soapy water for a few hours, instead of wiping the goo off, because wiping it could scratch the optical elements or the surface finish.

Now that's what I'm looking for when I want something that's "weather sealed".  And I bought it in the form of a Canon D20.  Until it says something similar in the manuals for our dSLRs, I'm not trusting them in heavy weather.  Sure, a bit of rain isn't a big deal, but I've had my Rebel + 15-85IS in light rain and drizzle without an issue either.

[mrsfotografie]

In the late 70's Canon switched its FD mount from the old design with a coupling ring to the "standard" bayonet. And they made the first "plastic" lenses e.g. the 35...70mm/3.5-4.5. The magazines were full of discussions why this would be the death of Canon and a shame - while Canon said those "plastics" would be more precise and durable than metal...

My 35...70 (bought in 81) still works perfectly (and my other FDs too!) though I didn't really kept an eye to them while shooting outdoors... A full metal Tokina isn't working for a long time now and my "full metal" german Exakta from the late 60's is working but not smoothly...

And the brakes of some super sport cars are also made of "plastics" - or isn't carbon fibre not a kind of "plastic"?

'Carbon fibre' is in fact a composite; there are carbon fibers in an epoxy resin-type matrix. The Epoxy is a 'plastic' so it is in fact reinforced plastic. The principle is the same as reinforced concrete, where the concrete carries the compression, and the steel the tension.

[Lee Jay]

I think Rogers's definition of a plastic vs. a metal mount differs from how most people think about those terms.  For most of us, we're talking about the bayonet parts - the 'teeth' that lock into the mount on the camera. 

Correct.

[infared]

Hey...NEW INFO....
Just went on to an MFT blog and another photographer just had the mount break off his Olympus "PRO" 12-40mm..here is what he had to say...and according to him...Olympus admitted that there is an issue....

Nicholas: “The mounting plate of my M.Zuiko 12-40 PRO lens broke off, just as others have reported. Three of the four screws sheared. This happened while mounted on an E M-1(with Battery Holder) in a padded Lowe Pro Bag. The bag fell off a bed onto a heavily padded hotel carpet. It was such a minor fall that I didn’t even look inside the bag when it happened. I only realized the lens was damaged the next morning when I took the camera out of the bag.
I called Olympus and they acknowledged there was “an issue,” and assured me that warranty would cover the repair. Perhaps most troubling: The technician iI spoke with admitted that they do not have a fix. He encouraged me to keep checking the website for updated information.“

[noncho]

The weather sealing part was awesome
I'm going for some tape to make my lens sealed too...

[fugu82]

Wouldn't "all metallic construction" be kinda hard to see through? And those all metallic circuit boards would be tricky to engineer.

[Normalnorm]

I think Rogers's definition of a plastic vs. a metal mount differs from how most people think about those terms.  For most of us, we're talking about the bayonet parts - the 'teeth' that lock into the mount on the camera. 

 

The EF-S 18-55 on the left has a 'plastic mount', the EF 17-40L on the right has a 'metal mount'.  Very few of us disassemble lenses, so we have no idea what's behind that mount surface.  Roger is talking about how the screws that that attach that visible surface piece to the lens are connected - do those screws go into metal screw-holes that are attached to the frame of the lens, or are the screw-holes plastic?

'Plastic' can be quite strong, so for a 'light' lens (most lenses under 100mm, with the exception of the 'magic cannonball' 85L), I agree with Roger that I wouldn't expect any issues, and 'professional' could apply.  However, for the bayonet 'teeth' of the mount, plastic wears down more easily than metal (vs. the screw-holes, which aren't subjected to routine 'wear'). That means a lens with a plastic mount (as I'd say is the common definition pictured above, not Rogers's use of the term), would be able to tolerate fewer mount/unmount cycles than a lens with metal bayonet teeth.  Since a professional lens would be expected to last years and most 'pros' own several lenses and change them frequently, it makes sense to associate a metal mount (as pictured above, regardless of how it's screwed in) with 'professional' build.

While I agree with you, I note that the article was provoked by the current furor over the Olympus lens that has a metal bayonet mounted on a plastic base like most lenses ( as Roger notes) and that THAT revelation of the use of plastic in a critical part is sparking the rage on the nets.

Weather proofing is another area where I have rolled my eyes for years. The most vulnerable part of the photographic assembly is the front element and other than using a Nikonos I see no protection of consequence offered by the claims of weather resistance.

[scottburgess]

Very funny thread.  I was amused by this when it got going more than twenty years ago, since with the small size of most lenses a metal housing made no sense.  But then the fanboys started complaining about it, so they added the thin metal plate on the outside of the plastic mount to make them happy.  Today the fanboys are shocked, SHOCKED!    to learn that the point of weakness was moved only a millimeter away and have taken up defending their rear metal cover as if it makes a huge difference in the wear-and-tear of the lenses. 

This despite the clear evidence offered that said metal plate covers are not any better or worse than the plastic covers.  Of course, there must be something wrong with Roger's evidence, because certainly he would have more mount repairs in the database if he restricted the definition of mount to be just the outer plate!  Hoo hoo!   

My own experience confirms what Roger and Aaron note: the plastic mounts of lenses I bought in the 90's are not worn off, or exploded, or oozing mysterious plastigoo, and in fact show little wear over twenty years of use.  I suppose one may eventually wear out.  Maybe I could achieve this if I sat 2-3 hours per day attaching the lens to a body, then removing it, over and over and over...   no doubt some fanboy will now be "testing" lenses this way and ceaselessly posting "durability" data on the Intertwitternet.   

Fanboys remind me of the old couch potato saw: "Oh, sports?  Yeah, I love sports.  I could watch them all day."

[Daniel Flather]

Look at the mount on the body, it's metal, but what is it attached to?

[Random Orbits]

And this is one reason why I don't like how most reviewers evaluate "build quality."  They evaluate the feel of the materials of the parts they can see, which is a mistake.  Think of cheap faucets with nice finishes but plastic gears.  The same thing happens with lenses.  Having a metal outer barrel is not indicative of the materials used for the inner assemblies that often matter more...

[vscd]

I think Rogers's definition of a plastic vs. a metal mount differs from how most people think about those terms.  For most of us, we're talking about the bayonet parts - the 'teeth' that lock into the mount on the camera. 

Correct.

I second that. I think Roger Cicala is surely someone who know a lot about lenses, but in this case I think he got the crowd wrong. I would never think of something the screw mounts in, when I hear of "plastic mounts". I guess they were all talking about the plastic rear-element which fits into the bayonett. Sorry, Roger, lot of verbiage for nothing... you thought too loud.

[fugu82]

It's all about sample size. My experience, with a lens that I use maybe 4 times times a year, even 20 busy pros experience with that lens using it every day, are statistically meaningless compared to a huge rental organization's repair data on that lens.

[Viggo]

I think Rogers's definition of a plastic vs. a metal mount differs from how most people think about those terms.  For most of us, we're talking about the bayonet parts - the 'teeth' that lock into the mount on the camera. 

 

The EF-S 18-55 on the left has a 'plastic mount', the EF 17-40L on the right has a 'metal mount'.  Very few of us disassemble lenses, so we have no idea what's behind that mount surface.  Roger is talking about how the screws that that attach that visible surface piece to the lens are connected - do those screws go into metal screw-holes that are attached to the frame of the lens, or are the screw-holes plastic?

'Plastic' can be quite strong, so for a 'light' lens (most lenses under 100mm, with the exception of the 'magic cannonball' 85L), I agree with Roger that I wouldn't expect any issues, and 'professional' could apply.  However, for the bayonet 'teeth' of the mount, plastic wears down more easily than metal (vs. the screw-holes, which aren't subjected to routine 'wear'). That means a lens with a plastic mount (as I'd say is the common definition pictured above, not Rogers's use of the term), would be able to tolerate fewer mount/unmount cycles than a lens with metal bayonet teeth.  Since a professional lens would be expected to last years and most 'pros' own several lenses and change them frequently, it makes sense to associate a metal mount (as pictured above, regardless of how it's screwed in) with 'professional' build.

Exactly! It's the wear and tear over time mounting and dismounting that I was thinking of also. I have seen lenses tried mounted a bit tilted and a piece of plastic has broken off. I also seen a few 50mm f1.8 and the Nikon 18-105 split apart on the middle of the barrel. I have also tried to kill a lightweight 17-85 with brutal force without success, if it was a heavy lens it would have exploded.

Weather sealing is always a funny term, but I have used my gear in VERY heavy rain without issue and once took my 85 L, which isn't sealed, into light rain and it fogged up right away, so there is something to it.

The truth hurts and I love these mythbusting articles from Roger, great read!

[LetTheRightLensIn]

Not surprised by any of it at all. (although I think he uses the term metal mount differently than most people, that said, he does bring up anchoring which many probably don't think to think of)