[rojogannon]

Ok so here's the thing.
There is nothing wrong with plastic lens mounts right ? Well I beg to differ after my recent experience.
About three years ago I bought the penta da 50ml f1.8 with plastic lens mount. At the time I thought nothing of it. It didn't turn out to be a particularly useful lens so I haven't used it much at all.
This year I have noticed Pentax used DSLR cameras are selling cheaply so I decided to buy more cameras, and started to use the da 50 a bit more.
Also I got a bit more confident with changing lenses which was something I had avoided doing too much because I wanted to keep the sensor clean. In fact I've never needed a professional sensor clean because the in built system is quite well designed. So I have plucked up more courage and I'm using all my lenses more frequently which means I am enjoying the fun of photography much more than before.
Occasionally I have noticed quite a few black specks appearing on my dining table where I carefully change lenses. I didn't really think about their origin until one day after cleaning the table and then swapping lenses the black specks appeared again. I had just removed the da 50 from my camera.
So every time I remove this lens from a camera, the black specs appear. So I then thought, what if these black specs are getting into the camera as well ?
So I have had to methodically check all my cameras using a blower first in the mirror box ( which found and removed a fair few black specks and in one case having to raise the mirror to use the blower in the sensor area as well. I don't think any specks had got into the sensor area but there was a tiny thread which was removed.
So is it really sensible to use plastic mounts for lenses?

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Last edited by gatorguy; 04-17-2022 at 03:27 AM.

[Serkevan]

That sounds more like the foam bumpers of the mirror assembly than the mount, actually... does the mount look scratched/damaged?

[Terry C]

I use my 35mm and 50mm plastic fantastics often on three different bodies, and never had a problem.

[BigMackCam]

It's just possible, I suppose, for the camera's metal mount to have sharp edges that might shave bits off the plastic lens bayonet. In practice, I've not had a problem with my own DA50/1.8 on any of the cameras I own...

[Madaboutpix]

Hm. If anything, the DA50 attaches super-smoothly to my K-3. Have never had any mounting issues, nor have I noticed it shedding any plastic debris whatsoever, and certainly not from the lens mount, which is still looking and feeling (to the touch) as if I had barely used that lens in the past seven years, when quite the opposite is true, actually.

If the mount of your DA50 looks intact and there's nothing wrong with your camera mount(s) either, chances are the culprit lies elsewhere: your blower shedding or spreading something, internal flocking from camera or some other lens, a less than lint-free lens cloth, foam debris (as suggested by Serkevan above), some source of stuff above or around your dining table, ...

Otherwise, could there have got any foreign matter inside your DA50, given that the barrel design would conceivably allow for that to happen if the lens was used in a dusty or sooty environment?

[pepperberry farm]

Ok so here's the thing.
There is nothing wrong with plastic lens mounts right ? Well I beg to differ after my recent experience.
About three years ago I bought the penta da 50ml f1.8 with plastic lens mount. At the time I thought nothing of it. It didn't turn out to be a particularly useful lens so I haven't used it much at all.
This year I have noticed Pentax used DSLR cameras are selling cheaply so I decided to buy more cameras, and started to use the da 50 a bit more.
Also I got a bit more confident with changing lenses which was something I had avoided doing too much because I wanted to keep the sensor clean. In fact I've never needed a professional sensor clean because the in built system is quite well designed. So I have plucked up more courage and I'm using all my lenses more frequently which means I am enjoying the fun of photography much more than before.
Occasionally I have noticed quite a few black specks appearing on my dining table where I carefully change lenses. I didn't really think about their origin until one day after cleaning the table and then swapping lenses the black specks appeared again. I had just removed the da 50 from my camera.
So every time I remove this lens from a camera, the black specs appear. So I then thought, what if these black specs are getting into the camera as well ?
So I have had to methodically check all my cameras using a blower first in the mirror box ( which found and removed a fair few black specks and in one case having to raise the mirror to use the blower in the sensor area as well. I don't think any specks had got into the sensor area but there was a tiny thread which was removed.
So is it really sensible to use plastic mounts for lenses?

check the mount of the lens for gouges or grooves being worn into before blaming the lens mount....

[UncleVanya]

Zero issues with my plastic lens mounts in the past.

[Not a Number]

I don't have any lenses with plastic mount. I do have a MZ/ZX-50 with a plastic mount. It's not entirely plastic as the tension springs and lock pin are metal. The camera has the broken mirror motor gear so I don't use it so I can't say anything about durability. Zero problems with fit on the rare occasion I try mounting a lens on it.

[Wheatfield]

The OP has not actually told us he has inspected the lens flanges to see if there is any erosion of the mount.
Failing that, there isn't much to discuss here.

[mikesbike]

Yeah, I'd get a good magnifying glass, some well-directed light, and take a careful look.

[Kobayashi.K]

Welcome to the forum @rojogannon. I fully agree with your header and gave you a thumbs-up for that, which is now 25% of your number of posts

[DonV]

"So is it really sensible to use plastic mounts for lenses?"

Yes, to produce a less expensive (and lighter) lens; you always have the choice to spend more if you wish- not everyone so desires.

[kypfer]

I have several Pentax lenses with "plastic" mounts that get swapped between bodies quite frequently and as yet I've not seen any trace of "plastic shavings" or similar in any of my cameras.
If one (or more) of my cameras was "shaving" the lens mount I'd get it looked at as a matter of urgency.
A few plastic specs may be little more than inconvenience now, but it does imply that the lens mount is likely to wear prematurely.
What would be of more concern is that if "something" is abrading plastic lens mounts, what's the chance of getting a few brass or other metal filings from other lenses in my cameras … no thank you!

[ChristianRock]

I'm pretty sure it's not the lens mount

[Theov39]

I've never had this issue with recent cameras but in my old film cameras, the foam around the mirrors would flake like that. Is that a possibility here as the DSLRS also have some foam damper above the mirror?

I think it is unlikely that it is 'shaving' small pieces of the lens mount as then it is likely that other users would also have reported this problem.

Alternatively, there could be a one-off problem with your particular lens. It is not inconceivable that plastic deteriorates over time.

Having said that, I agree with the OP that metal mounts are preferable. They even look better when you can see them