# Loose aperture ring on an old 50mm



## panblue (Oct 13, 2012)

I picked up a 50mm cheap the other day. It has the A/M switch and pin. 
When I set the ID to manual and stop down sometimes turning the ring engages the blades,
 sometimes not...or rather sometimes from full-open only to about f8, other times from full-open
 all the way to f22.

I sussed that when i hold the lens pointing upwards, then the iris stops all the way down. 
If i turn the lens over and invert it, or also hold it level, as it would be mounted, the iris doesn't stop down fully.

I seems like the tiny ball-bearing race, under the ring is looser than it should be. Gravity does
the trick when the lens is held upright.

On the back of the lens are the typical, three screws plus another, smaller screw.
I tighten the smaller screw a little..and the iris fails to close at all. So i returned the screw 
tension to its original position.

Increasing the tension of the three main screws doesn't appear to compress the casing of 
the lens at all, or the way the bearings are seated under the ring.

How easy is it to replace these bearings? Can I coat the bearings in some way or add any
 substance to firm things up just a bit. The tolerances involved seem very small.


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## compur (Oct 13, 2012)

It would help if you mentioned what lens it is since there are differences in construction between the many lenses that have been manufactured over the years.

I would also suggest asking your question (with lens ID) here:
Topics - The Classic Camera Repair Forum


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## unpopular (Oct 14, 2012)

I'm going to guess that this could be a really easy repair; the coupling that catches to aperture pin is probably slightly bent or warn a bit.

Is the aperture ring on the front of the barrel, or on the rear? It could also be that the pin itself has come loose, and this might be more difficult to repair.


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## panblue (Oct 14, 2012)

1.8/50 Pancolar, 1974 serial; black copy, red markings.



compur said:


> It would help if you mentioned what lens it is since there are differences in construction between the many lenses that have been manufactured over the years.


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## panblue (Oct 14, 2012)

unpopular said:


> I'm going to guess that this could be a really easy repair; the coupling that catches to aperture pin is probably slightly bent or warn a bit.
> 
> Is the aperture ring on the front of the barrel, or on the rear? It could also be that the pin itself has come loose, and this might be more difficult to repair.


  To the rear. I'm using switched to M, so I doubt the pin's relevant to the problem (plus the fact that when the len's is upright, the ring functions normally, with the pin hanging extended from the lens..if i turn the lens over, or test it level, the ring only partially stops-down the iris).

As there appears no external adjustment to mate the ring more securely..my assumption is the correct friction is achieved using ball-bearings. What do you think?


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## panblue (Oct 14, 2012)

This lens cost me about US$7. You can see on ebay what they go for (MC version). How much do you think a typical repair-job would cost me? $50 or so?


This version (ebay photo)...
http://i.ebayimg.com/t/Carl-Zeiss-J...Aw/$T2eC16hHJF8E9nnC9cJSBQNebwbIqQ~~60_35.JPG


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## unpopular (Oct 14, 2012)

probably more than that. I looked into having my Minolta 50/2.8 cleaned, but it cost more than the lens was worth.

Will the lens stop down normally with the auto aperture pin depressed? You can place a dab of super glue on the stop down pin while it is depressed with the point of a knife. After a few moments, it will stick permanently but not to the knife. You then just can let the glue dry over the next several hours and use it in permanent manual mode. I did this on my Porst.


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## panblue (Oct 14, 2012)

unpopular said:


> Will the lens stop down normally with the auto aperture pin depressed?


 No, same problem.



unpopular said:


> You can place a dab of super glue on the stop down pin while it is depressed with the point of a knife. After a few moments, it will stick permanently but not to the knife. You then just can let the glue dry over the next several hours and use it in permanent manual mode. I did this on my Porst.



You drive a Porst? very cool!   I think my balls aren't bearing.


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## unpopular (Oct 14, 2012)

I don't know, man. I've taken apart a few lenses, and I have never encountered ball bearings. Maybe in higher quality lenses?


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## panblue (Oct 14, 2012)

unpopular said:


> I don't know, man. I've taken apart a few lenses, and I have never encountered ball bearings. Maybe in higher quality lenses?



I wouldn't have either, if I didn't have a vague recollection of disassembling (destroying) a CZJ Tessar and finding a tiny ball bearing afterwards.

aha!...

_Long story short - I lost the tiny ball bearing that rides under the aperture ring of my ​SMC M ​50mm F2 lens.​_

From PentaxForums.com: Missing ball bearing. - PentaxForums.com
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