[stevebrot]

Come on stevebrot. That's not having a problem under normal use, that's willful destruction.

What I might do with a bit of emery paper in a few seconds is the same as a few hundred mount/unmount with the environmental grit common in the drier parts of my region. The plastic mounts work great when clean is the norm, but for field use, clean is often a luxury and the native grit is often equivalent to what is glued to sandpaper.


Steve

[Macario]

The biggest thing is that plastic is cheap, and doesn't feel as solid as metal.

Do you drive a car? (big part made of plastics these days)
do you fly? (big parts of planes are composite plastics)

[jddwoods]

It's not about the material, it's about build quality.
The Angenieux zooms with policarbonate barrels were very well built, and have proven durable, but at the time they didn't enjoy the commercial success they deserved because photographers expected high quality lenses to be all-metal.
I'm testing turn of the century "silver" FA zooms. The construction is awful, but the average optical quality is superior to better built early FA and F counterparts.
The problem lies in durability and easy/possible repair procedures.
If a lens group is glued or set in a plastic casing, the only option is to find a spare.
BTW, I never found a metal zoom out of whack, but with no signs of damage. TWO expensive f/2.8 zooms looking absolutely pristine had bent focusing/zooming "tubes", causing vignetting and other problems.
The day the spares will be unavailable those very good and highly valuable lenses will be usable only as doorstops
Sigma still has spares for film era objectives. If I'm not mistaken some Pentax spares for slightly newer lenses are nowhere to be found.
If a partly plastic lens has brass-on-aluminium retaining rings, and cams/tubes/helicoids made of durable materials, that would be a high-quality objective that would last forever.
Plastic is not the devil.
Unfortunately a wobbly, plasticky barrel is often the sign of a very poor construction. A few of my wobbly zooms are surprisingly good... but I made sure to buy like new examples.
Some of my vintage lenses with great all-metal build are very worn and have horribly bent filter threads, but the optical performance is so good to make me think they perform as when they were new. A plastic lens would never survive a crash that causes that kind of damage.
When I mention durability I'm also referring to electro-mechanical problems. Some FA lenses are failing. My FA Macro 100mm, that is NOT cheaply built, had a problem with the limiter switch (AF problems). It has gone under surgery to repair the switch. I don't believe a cheap poorly made zoom would be as easy to repair, because containing costs has a price, if something fails.
Most of my favourite Pentax were purchased second-hand in the late seventies or early eighties. All of them work as the first day. Three of my very expensive zooms had to be repaired (one of them because it became a fungus nest while the other metal lenses stored in the same place where unaffected). Yes, plastic welcomes fungi more than metal. Personal experience.

I agree! With my K-5 and K-3 bodies, I have an assortment of plastic (FA 50mm f1.7, DA 16-85 and DA 55-300 PLM), Plastic and metal (F 28mm f2.8, DFA 100 macro WR) and metal ( M50 f1.7, all 5 DA Limiteds, DA* 200 and 300 primes) lenses. While the two zooms are plastic, they feel solid and well built with nothing loose or wobbly and give me no worries about them failing due to poorer quality materials and build quality. The older FA 50mm does feel "plasticky", especially compared to its M50 f1.7 counterpart, however I use the FA 50 far more than the M 50 due to what seems to be better versatility and image quality. The metal lenses just feel better but I think a lot of it is perception more than anything else especially with higher quality plastic lenses. My one concern with the plastic lenses is the durability of the filter threads. I think this is where metal has a definite advantage.

[ZombieArmy]

I
Some of my vintage lenses with great all-metal build are very worn and have horribly bent filter threads, but the optical performance is so good to make me think they perform as when they were new. A plastic lens would never survive a crash that causes that kind of damage.

My F35-70 crashed straight into the floor front first off of a tripod and ended up with the barrel bent. Knocked it back into place and good as new!
I think plastic lenses do have more limited/more difficult repair ability but I think metal lenses could actually damage more easily thanks to the added weight.

As an aside, my Samyang 14mm is one of the nicest feeling lenses I own.

[BigMackCam]

Also, let's not forget that most all-metal lenses we buy today have one or more plastic components inside - especially auto-focus lenses. All-metal bodies might inspire conifdence, but they often hide internals that aren't so different from plastic-bodied alternatives...

[mikesbike]

In both camera bodies and in lenses, there are plastics, and then there are plastics. There are substantial differences in the quality of the material. I have numerous lenses of higher quality plastic construction that are excellent lenses, and very well-made. I also have a few that are of mid-grade material, that are still very good-performing optically. I also have quite a number of high-quality lenses of metal construction. So there is no set rule that says never buy a lens of plastic construction. The Pentax DA 18-135mm, for just one example, is a very well-made lens, even though compact for its zoom range.

Although I do have a couple of lenses having plastic lens mounts, these I do not subject to ongoing heavy use. I have known of cases where after time such mounts have started leaving stains requiring cleaning the camera's lens mount, or even tiny shavings. However, such mounts are easily replaced.

[TwoUptons]

We used to joke 20+ years ago that cheap cameras and lenses were made of plastic. Expensive ones were made of 'polycarbonate'...
I don't think much has changed in that respect, except maybe now it's 'plastic' vs. 'composite'.

I also remember being told about the same time that the Minolta SRT was one of the first successful SLRs to use nylon gears (I think as part of film transport).
Despite its reputation as reliable, it doesn't make me feel much better about the longevity potential of my ZX-L...

-Eric

[UncleVanya]

Also, let's not forget that most all-metal lenses we buy today have one or more plastic components inside - especially auto-focus lenses. All-metal bodies might inspire conifdence, but they often hide internals that aren't so different from plastic-bodied alternatives...

This isn't just a modern thing. I have an A series 70-210 that arrived broken from eBay. Dcshooter had to fabricate some new plastic cams to get it to work even halfway.

[AggieDad]

Thanks to all for the responses and the interesting discussion.

The one thing that came through to me is that there does not seem to be any smoking gun. There were many mentions of how it was in the 80s; how it feels; what might happen; etc. However, I did not really read any anecdotes about lenses falling apart, etc. In other words, "plastic" lenses apparently are just fine once you accept that they are plastic and not metal.

Given this lack of empirical data, it would seem to me that we should get over the issue of the material with which a lens is constructed, and focus (pun intended) on the performance of the lens. To note the material of construction is one thing – and useful, but to be dismissive because of that material is neither fair nor necessary with today's technology.

Don

P.S. There were a number of mentions referring to "how a lens feels." Is lens fondling a thing? Is this some part of the photography hobby I am missing? Do we have a forum thread about this?

[wanderer2]

I've been looking through the lens reviews (more dreaming than planning) and have noticed that every time a lens is constructed of plastic that the issue is considered a negative. So I got to wondering...

Has there been a problem with plastic constructed lenses? Do they fall apart? Do they suddenly stop focusing? Why does the plastic seem to be considered is a major negative?

I have no background in chemistry or plastics (I'm a math guy, a teacher), but I do know that there are many, many things built of some pretty tough plastics. In fact in many instances, plastic construction can be an advantage – I do like the weight savings with my Sigma 150-500.

Anyway, what am I missing? What I am going to lose – other than some weight to carry – when I buy a plastic lens?

Just wondering.

Don

As previously noted, plastics have long been considered inferior to metal in strength, resistance to beakage, etc. However, plastics are now much improved and very strong. As an example, awhile back I dropped a very heavy totally plastic bodied portable electric drill from a height of 12 feet onto concrete with no dents, cracks, or hardly even a scratch. If it had been metal I think it would have at least been dented. I personally would not turn down a lens I wanted just because it was plastic.

[angerdan]

Also, let's not forget that most all-metal lenses we buy today have one or more plastic components inside - especially auto-focus lenses. All-metal bodies might inspire conifdence, but they often hide internals that aren't so different from plastic-bodied alternatives...

Plastic Mounts and Professional Construction:
Assumptions, Expectations, and Plastic Mounts - Lens Rentals Blog

[mikesbike]

It seems I read a recent post of a newer plastic Pentax lens did have some part of it come off. One of the less robust plastic lenses of the Pentax line is the DA 50-200mm, even the WR version. Even if working properly at first, I have known of some such lenses that have developed wobble in the zoom components, and zoom creep when pointed downward.

Just for examples, if you were to handle the the DA 18-135mm and then the DA 18-55mm and DA 50-200mm, taking some shots with each and using their zoom mechanisms also, you would definitely notice a difference in the superior quality of construction as well as the superior In-use performance of the DA 18-135mm lens. And yet all are of plastic construction. The DA-L versions of the two kit lenses have plastic lens mounts as well.

[BigMackCam]

Even if working properly at first, I have known of some such lenses that have developed wobble in the zoom components, and zoom creep when pointed downward.

Zoom creep isn't, in itself, an indication or poor quality or wear, though... it can happen in some quite high-end lenses with heavy optical arrangements as they loosen up from use (I've heard reports of slight zoom creep on the DA*60-250, for instance - although mine doesn't do it... yet).

Wobble, of course, is another matter.

[SSGGeezer]

Zoom creep isn't, in itself, an indication or poor quality or wear, though... it can happen in some quite high-end lenses with heavy optical arrangements as they loosen up from use (I've heard reports of slight zoom creep on the DA*60-250, for instance - although mine doesn't do it... yet).

Wobble, of course, is another matter.

The Big Sigmas like my 120-400 have a lock at the wide end for a reason. 4 pounds of plastic and glass means that zoom creep is a fact of life!

[Jonathan Mac]

I've recently been looking into the possibility of getting a Fuji 16-50mm kit lens for my Fujifilm camera, and like a couple of Pentax lenses, it has a plastic mount. While I haven't come across any cases of the Pentax ones breaking, I have read a report or two of this happening on the Fuji.

Plastic, like any material these days (even steel), comes in many different qualities. I'd certainly prefer metal over plastic, especially when it comes to a mount, but in small lenses I wouldn't out-right avoid a lens purely due to it having a plastic mount. I would however never buy a plastic mount big zoom lens, I think there's a DAL 55-300mm like that.

I know that some people have transplanted a metal K-mount onto the DAL 35mm f/2.4 in order to gain a metal mount, but I don't know how easy it is or if it would really matter in a lens so small and light.