[enricob]

Hi,

I have a problem with an SMC Pentax 67 90 mm F2.8 lens.

I realized that maybe there is something inside the lens, because, rarely, the focusing ring is blocked. It is not completely blocked, it is blocked just in one way, it is not blocked in case you move the focusing ring back. In these cases it's enough to move and slightly tilt the lens and then the focusing ring is unblocked. The first time, just one time, the diaphragm ring was blocked. Then only the focusing ring has blocked, but just sometimes, rarely. For example, no issue at all the last time I used the lens for many hours.

At the same time, there is this little broken hanging chain inside the camera body




and therefore, probably, a little piece of this chain entered inside the lens.

No problems regarding the camera body, as I have another one. But I'm considering to save the money for a technician opening and cleaning the lens, and so I'm considering to use the lens with this little piece inside the lens, because I do not plan to use this camera and lens for long, just the last rolls left during the next two months.

Question: in case I would keep on using the lens with this little thing inside, do I risk any further and worse damage? Does this little thing inside the lens could cause some further damage and the lens could be suddenly unusable?

Mostly, is it also possible that this little thing inside the lens will damage the lens in a way in which this damage could not be clear, not evident, so the lens could apparently keep on working in a proper way, but to then realize that the lens worked badly only after the rolls are processed and therefore when the pictures are all irreparably lost? This is the most important question, of course because this kind of issue could not even be remedied before than a lot of pictures are lost.

Or, instead, should there be no further problems and the lens should work properly, no “hidden” issues possible, as this little thing could only rarely and temporarily block the focusing ring as I have already described, but no more than this?

( Just in case, is it quite easy to open the lens to try to remove this small thing inside the lens? Can an inexperienced user also try? Is there a guide you explain how to do it? Or is it better to make it do to an expert and qualified technician? )

Thank you very much,

Enrico

[Not a Number]

Moved to the medium format section.

The broken meter coupling chain is a known problem and existing threads contain suggestions for repair. The lens issue could probably be solved with a DIY repair provided one has the tools and confidence and/or experience to attempt the repair.

Broken Chain on 67 - PentaxForums.com
ADVISORY: Pentax 6x7, 67 METER COUPLING CHAIN AND TTL METER PRISM - PentaxForums.com
Pentax 67 broken chain
Pentax 67 Broken chain? - PentaxForums.com
Another 67 TTL Meter Chain Thread - PentaxForums.com

DIY repair video (chain):

You Tube

You Tube

[enricob]

I don't need to repair the chain, not yet, because I have another body camera.

The only problem concerns the lens, but I didn't find any DIY repair video about opening some Pentax 67 lens.

Even today I used the lens for a few hours and I had no issue, the focusing ring and the diaphragm ring worked without hitches.

But I wonder if this appropriately working lens could instead have some “hidden” damage I can't see and could therefore damage all the photographs, etc, as I have already explained in the first message of the thread.

Thank you.

Enrico

[photoptimist]

Question: in case I would keep on using the lens with this little thing inside, do I risk any further and worse damage? Does this little thing inside the lens could cause some further damage and the lens could be suddenly unusable?

Mostly, is it also possible that this little thing inside the lens will damage the lens in a way in which this damage could not be clear, not evident, so the lens could apparently keep on working in a proper way, but to then realize that the lens worked badly only after the rolls are processed and therefore when the pictures are all irreparably lost? This is the most important question, of course because this kind of issue could not even be remedied before than a lot of pictures are lost.

I would say yes that more damage to the lens, camera, and pictures are possible (but not very likely).

If you think a bit of broken chain migrated from the camera body into the lens, then it's possible that this bit of chain might migrate back into the body where it could: damage the shutter, scratch the film by getting lodged in the film transport, prevent proper focusing by fouling the mirror. etc. Precision camera mechanisms don't take kindly to random bits of metal.

Sure, it's very unlikely to do so but why risk it?

I'd use a different lens until you can repair or replace the one that contains loose bit of mischievous metal.

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Last edited by photoptimist; 03-18-2023 at 09:09 AM. Reason: clarity

[Not a Number]

The lens is a prime and not a zoom so the construction should be fairly standard to other prime lenses in the series.

You Tube

You Tube

You Tube

You Tube

If there is a bit of chain in the lens odds are it is probably trapped in the focus helical grease. Depending on how embedded it is you might get lucky and be able to tap it loose. You could try holding the lens at a 60° angle to the floor rear down and tapping the barrel of with a wooden stick like a pencil or chopstick. Maybe with a lot of luck it will drop out. Or might fall to some place else where it could do some damage.

Photoptimist's recommendation not to use the lens is sound.

[enricob]

The lens is a prime and not a zoom, so the construction should be fairly standard to other prime lenses in the series.

I had a look, but I think I have no tools and experience enough to attempt the repair.

If you think a bit of broken chain migrated from the camera body into the lens, then it's possible that this bit of chain might migrate back into the body where it could: damage the shutter, scratch the film by getting lodged in the film transport, prevent proper focusing by fouling the mirror. etc. Precision camera mechanisms don't take kindly to random bits of metal.

Sure, it's very unlikely to do so, but why risk it?

You are right, I didn't realize that this bit of chain might also migrate back into the body and cause a lot of damage also inside the body camera.

Then, I don't know, not yet, but now I have the information I needed to evaluate the risk.

Thank you all,


Enrico

[enricob]

What's more, as this loose piece of metal could block the aperture from closing when the picture is taken, leading to overexposure, is it possible to check if the diaphragm ring is properly working using the DOF lever?

I mean: in case the diaphragm properly closes when the DOF lever is pressed, does it mean that the diaphragm is not blocked and is properly working, and therefore that it will work properly even when the shutter button will be pressed?

Thank you very much,


Enrico