Increasing "friction" in a collapsible lens ??

Joao

Joao

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Hello
Advice from RFF members prompted me to buy an interesting Zeiss-Ikon collapsible Tessar 1:28 f=5cm that fits nicely in my Kiev 4AM.

Photos and details in another thread:
https://www.rangefinderforum.com/forums/showthread.php?threadid=166413

However, I remark that when I point the camera vertically to the sky, the weight of the lens causes it to partially collapse into the camera. This happens only with the camera pointed 90º upwards.I can either stop taking photos to clouds or hold the lens barrel while taking a picture. But I would prefer to find a way to slightly increase the "friction" ("rubbing"? I don't know the precise word...) of the lens barrel in its mount.
Any sugestions ??
Thank you
Joao
 
There should be a lens lock. At least I am pretty sure that is usual for this type of collapsible lens (Leica ones certainly do and though its been a while since I have owned a Zeiss of this type I think they do too.). Try giving an eighth of a turn one way or the other (clockwise I think) and it may click into locked position.
 
Joao said:
Hello
Advice from RFF members prompted me to buy an interesting Zeiss-Ikon collapsible Tessar 1:28 f=5cm that fits nicely in my Kiev 4AM.

Photos and details in another thread:
https://www.rangefinderforum.com/forums/showthread.php?threadid=166413

However, I remark that when I point the camera vertically to the sky, the weight of the lens causes it to partially collapse into the camera. This happens only with the camera pointed 90º upwards.I can either stop taking photos to clouds or hold the lens barrel while taking a picture. But I would prefer to find a way to slightly increase the "friction" ("rubbing"? I don't know the precise word...) of the lens barrel in its mount.
Any sugestions ??
Thank you
Joao
Click to expand...

I had problems with the collapsible 50mm f/2 Sonnar belonging to a 1936 Contax II. It was OK when focusing it with the wheel, but would unlock itself if I tried to adjust focus by rotating the lens barrel, which eventually became a little annoying. But I sorted it easily, so with some care you should be able to rectify your Tessar, it uses the same, or similar, parts.

In the other thread you referenced, the second image in your opening post shows a (out of focus) ring with three lugs, which grip the slots on the inside of the lens barrel after you extend the lens and twist it into place. I'm not sure what material the ring is made out of.

The lugs are slightly flexible because after machining to shape they were slotted in order to provide a slight amount of give. It's why a lens in good condition will rotate smoothly and then lock into place when extended, because those slots beneath the lugs allow for a very slight degree of flex, and this locks the extended lens into position.

I am unsure if the cause of any excess play is wear of the inner lens barrel, the lugs, or a bit of both. Probably more likely the barrel, I suspect. In any case, I was able to get my collapsible Sonnar working very nicely again by gently inserting a slotted screwdriver with a one millimetre tip into each slot under its lug, and opening the end of the lug out by a very small amount. This compensated for any wear in the parts. Not being around in 1936, I can't say for certain, but my lens now extends and collapses like I think it would have done when new.

It would not be hard to break one of the lugs if you are hamfisted about the process. It's essential to be gentle and use the minimum possible leverage with your driver. I'll leave it up to you as to whether you feel confident to make the adjustment. I had no issues whatsoever, but I have also done quite a lot of camera or lens repair, and am used to doing these sorts of adjustments to old German kit. YMMV.
Cheers,
Brett
 
I am grateful for the several sugestions.

I explored Peter's sugestion more carefully than I did when I first tried the lens: there is indeed a very precise position of the barrel where it locks (I have several FSU collapsible similar lenses where the locking of the barrel is much more easy/obvious). I will make a few shots trying to get used to it as it is, and see what happens; maybe this will be enough.

Brett : I always use the focusing wheel in my Kiev, no problem with that.

I will leave for a last option all procedures envolving disassembling.

Thank you all again

Joao
 
This is absolutely correct. The collapsible Zeiss lenses for the Contax RFs do not have a lens "twist" lock like the Leitz lenses for Leica. I successfully performed the tab tightening technique Sarcophilus described on a collapsible 5cm/2 Sonnar.



Sarcophilus Harrisii said:
I had problems with the collapsible 50mm f/2 Sonnar belonging to a 1936 Contax II. It was OK when focusing it with the wheel, but would unlock itself if I tried to adjust focus by rotating the lens barrel, which eventually became a little annoying. But I sorted it easily, so with some care you should be able to rectify your Tessar, it uses the same, or similar, parts.

In the other thread you referenced, the second image in your opening post shows a (out of focus) ring with three lugs, which grip the slots on the inside of the lens barrel after you extend the lens and twist it into place. I'm not sure what material the ring is made out of.

The lugs are slightly flexible because after machining to shape they were slotted in order to provide a slight amount of give. It's why a lens in good condition will rotate smoothly and then lock into place when extended, because those slots beneath the lugs allow for a very slight degree of flex, and this locks the extended lens into position.

I am unsure if the cause of any excess play is wear of the inner lens barrel, the lugs, or a bit of both. Probably more likely the barrel, I suspect. In any case, I was able to get my collapsible Sonnar working very nicely again by gently inserting a slotted screwdriver with a one millimetre tip into each slot under its lug, and opening the end of the lug out by a very small amount. This compensated for any wear in the parts. Not being around in 1936, I can't say for certain, but my lens now extends and collapses like I think it would have done when new.

It would not be hard to break one of the lugs if you are hamfisted about the process. It's essential to be gentle and use the minimum possible leverage with your driver. I'll leave it up to you as to whether you feel confident to make the adjustment. I had no issues whatsoever, but I have also done quite a lot of camera or lens repair, and am used to doing these sorts of adjustments to old German kit. YMMV.
Cheers,
Brett
Click to expand...
 
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