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09-13-2011, 04:23 AM   #1
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Carl Zeiss Jenna lenses

I have two of these old lenses which I used with my Pentax film camera. A 35mm/2.4 and a 135mm/3.5.

I was playing around with them on my new Kr and the 135 works well although only manual, but the 35 aperture does not close down on either A or M setting altough the litte peg sticks out in A. I guess this means it is damaged in some way and I wondered if it was worth trying to fix it. The main reason is that it focusses down to 20cm and gives excellent images at almost 1:1. I am really getting into macro and this lense would give me a good start on the learning curve at no extra cost. I hope one of you clever people out there could advise me if I am wasting my time or not. I can use the lense at max aperture but get about a micron depth of field .

09-13-2011, 04:42 AM   #2
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Is this an m42 lens or k mount? If M42 then when in auto setting, when you turn the aperture ring does the aperture close at all? In A mode try pushing the pin in and out a few times and see if you get any reaction to the diaphragm (if its stuck maybe see if you can get it to unstick). If it is the same one that is selling on ebay for 200$ plus I would think that it would be worth trying to get fixed or at least check into it.
09-14-2011, 01:30 AM   #3
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Hi Ripit,

The lens is M42 and I have tried pushing the pin in A mode but nothing happens. In M the pin retracts as normal.

This lens has not been used for probably twenty years but is in mint condition so I would like to get it working.

Thanks

Mike
09-14-2011, 05:14 AM   #4
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QuoteOriginally posted by Chicken George Quote
I have two of these old lenses which I used with my Pentax film camera. A 35mm/2.4 and a 135mm/3.5.

I was playing around with them on my new Kr and the 135 works well although only manual, but the 35 aperture does not close down on either A or M setting altough the litte peg sticks out in A. I guess this means it is damaged in some way and I wondered if it was worth trying to fix it. The main reason is that it focusses down to 20cm and gives excellent images at almost 1:1. I am really getting into macro and this lense would give me a good start on the learning curve at no extra cost. I hope one of you clever people out there could advise me if I am wasting my time or not. I can use the lense at max aperture but get about a micron depth of field .
It's the usual problem of Flektogons 35/2.4 .The lubricant on the aperture blades gets dry and that causes the blades to stuck usually wide open.
I have both lenses and you can be shure that you're not wasting your time.
Here is a link that might help you clean those blades....I guess you could throw the aperture assembly into a volatile liquid for a while and let it dry totally after the wiping before you reassembly.

Flektogon 35/2.4
lens

And here is how to repair Sonnar ... but pay attention at the cleaning part if you decide to open the Flektogon.

Servicing The CZJ 135mm f/3.5 Lens

Samples with 35/2.4 MC Flektogon and K200







Sonnar MC 135/3.5 +K200




Last edited by stgeo; 09-14-2011 at 10:14 AM. Reason: Photos
09-15-2011, 06:30 AM   #5
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Stgeo,



Thank you so much for your fantastic email. It tells meexactly what I need to know and I am going to try it.



I will donate the money it was going to cost me for anestimate to the forum.



Regards



Mike
09-15-2011, 08:06 AM   #6
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My pleasure, Mike .
09-16-2011, 07:35 AM   #7
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Gold pins on rear of lens

The older lens's I have tried with my Kr have surprised me by becoming auto focus, something they did not do on my K1000. The 35/2.4 has gold pins on the back which do not appear to do anything. The lens is described as "electric" but I don't see any sparks!! Does anyone know what they do?

Mike
09-16-2011, 07:59 AM   #8
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Actuation of iris

I have disassembled the lens. There does not appear to be any mechanical connection between the actuation lever and the iris leaves. It moves freely.

Any further suggestions?

Mike

09-17-2011, 10:04 PM   #9
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QuoteOriginally posted by Chicken George Quote
The older lens's I have tried with my Kr have surprised me by becoming auto focus, something they did not do on my K1000. The 35/2.4 has gold pins on the back which do not appear to do anything. The lens is described as "electric" but I don't see any sparks!! Does anyone know what they do?

Mike
Don't bother , about the versions (electric) of the lens ..they're all the same and the pins are useless on our dslrs.

About the blades ,I never had to open mine ,so I can't help any further.....
If the blades are free maybe a broken -missing spring or something like that causes the problem.
09-19-2011, 11:25 PM   #10
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Thanks for the info. I was looking at the wrong lever, it was the one which moves as the aperture ring is turned. When I move the spring loaded actuator which allows the blades to open, I can shut the aperture down but it does not return open by itself. I can feel a resistance. Someone suggested the spring may have aged and not be strong enough. I hesitate to dismantal the mechanism any further as another poster said he had a pile of blades and no way to put them togehter again. I will keep trying and at least clean the lens with isopropyl alcohol while it is open. Thanks again for the help.
09-20-2011, 12:36 AM   #11
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Switching to M on the Flektagon should mean your aperture will open/close with aperture ring rotation. I haven't ever stripped my 35 f2.4 as it works fine, but I would suggest you look at what the lever/ switch should activate between the M and A settings. I remember a similar problem with a Super Tak 135 where a cam had shifted its orientation so was not allowing the lever to allow aperture actuation in M setting. Depressing the pin should help you see what needs to move for the M setting to function properly. Although rare as hens teeth, there are M42 to PK adapters out there with an inner flange which will depress the aperture pin, another possible option.
09-20-2011, 10:28 AM   #12
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QuoteOriginally posted by Chicken George Quote
Thanks for the info. I was looking at the wrong lever, it was the one which moves as the aperture ring is turned. When I move the spring loaded actuator which allows the blades to open, I can shut the aperture down but it does not return open by itself. I can feel a resistance. Someone suggested the spring may have aged and not be strong enough. I hesitate to dismantal the mechanism any further as another poster said he had a pile of blades and no way to put them togehter again. I will keep trying and at least clean the lens with isopropyl alcohol while it is open. Thanks again for the help.

I think that you might succeed ...if you work the blades while they're submerged in isopropyl alcohol , till they're perfectly clean .
Also leaving the aperture assembly submerged for some period before you start working with the blades might be a good idea .
If you google this , you'll find that it's a very common problem of the Fleks....

wish you luck.
10-15-2011, 11:28 AM   #13
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Success

I obtained some iso-propyl alcohol and went through the procedure again. Eventualy the iris began to close easily and repeatably. I put it back together and it would not work. I found that the re-assembly was very critical and at each point I checked the operation of the iris before tightening the screws very carefully. This time it worked and the lens appears to be back to its original working order. I did not lubricate the iris as I wasn't sure what to use and it did not seem to need it. At least thanks to the brilliant people on this most friendly of forums I can use it and if it fails again I know what to do.

Many thanks for the help.

Mike
02-25-2012, 10:39 AM   #14
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Hi, I am using Pentax k-X
anyone please help, where can get "Carl Zeiss Jenna 135mm, f3.5 Sonnar MC"
i am eagerly searching for it....

Thanks in advance
02-26-2012, 11:52 PM   #15
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QuoteOriginally posted by siddharth Quote
Hi, I am using Pentax k-X
anyone please help, where can get "Carl Zeiss Jenna 135mm, f3.5 Sonnar MC"
i am eagerly searching for it....

Thanks in advance
Spelt 'Carl Zeiss Jena' , only one N in Jena

Anywho I guess just the usual places, charity shops, online auction sites like ebay / keh, place wanted add's in the marketplace here, or just google and keep looking.

I just had a quick look on ebay uk, and wow, the 135 3.5 MC is going for 70 plus... I got mine for 5 from a charity shop, my M42 - K adapter cost more, lucky I guess
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