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Message |
    
Eugen__mezei
Tinkerer
Username: Eugen__mezei
Post Number: 1
Registered: 08-2008
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, August 18, 2008 - 05:01 am: | 
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Hi!
I got a Kiev 6C recently but the attached Vega 12B (90mm, 2.8) will not close the diaphragm.
Very interesting solution, the axis shutting the diaphragm is not pushing but rotating. Got so far to see this, but no further, need to acess the other end of this axis.
Anybody ever serviced this lens?
Greetings,
Eugen |
Glenn
Tinkerer
Username: Glenn
Post Number: 401
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, August 18, 2008 - 05:43 am: |
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In all the Pentacon 6 mount lenses/clones that I have come across, one can access the diaphragm actuating mechanism from the rear - well enough of it to get the linkage properly set up. I do not know the specifics for this particular lens, as I prefer the Jena products in this focal length. However in the Russian wide angles I have worked on, the mechanism is poorly engineered and items can get bent or loose very easily. |
Glenn
Tinkerer
Username: Glenn
Post Number: 402
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, August 18, 2008 - 12:11 pm: |
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Further to the above:- Remember that on these lenses, the actuating lever is pushed in to open up the diaphragm for focusing. The camera mechanism releases the pressure on the pin, to stop down the lens - done by a spring in the lens barrel moving the pin. This means that with the lens off the body and no finger pressure on the pin, rotating the aperture ring will move the diaphragm to the corresponding values.
If your lens does not function off the camera as above, is the actuating pin in the extended position or pushed in?
Apart from the diaphragm blades being damaged/stuck together, there could be a couple of simple causes for your problem. 1/ The spring that powers the 'stop down' is missing/broken or detached from the internal lever. 2/ Does this lens have a preview lever/button on the barrel? On this type of actuating mechanism - if the preview lever is operated when the lens is at maximum aperture, it can jam in the preview position, hence the lens will remain at maximum aperture. This is most likely to happen on lenses that have parts manufactured to wide tolerences - a problem with most actuating mechanisms on P6 mount Russian optics. However as I indicated, I do not know if this lens is fitted with a preview lever on the barrel. |
Reborn7
Tinkerer
Username: Reborn7
Post Number: 18
Registered: 11-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, August 22, 2008 - 06:32 am: |
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I have the same combo Kiev 6C + Vega 12b, the lens has a diaphragm actuating pin which is pushed in when the lens is mounted on the body AND the shutter cocked - this opens the diaphragm fully.
A preview lever on the camera lensmount lowers the pressure on the actuating pin (as if the lens were dismounted) and closes the diaphragm.
So, you need to find out if the lens is faulty or the camera mechanism :
check the unmounted lens - with no pressure on the actuating pin the diaphragm should open and close when you rotate the diaphragm ring, with actuating pin depressed the diaphragm opens fully.
The camera/diaphragm actuating axis is combined with the mirror mouvement mechanism, when the shutter is cocked the mirror is brought down and the diaphragm actuating rod comes forward pushing the lens pin. |
Eugen__mezei
Tinkerer
Username: Eugen__mezei
Post Number: 3
Registered: 08-2008
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, August 29, 2008 - 11:45 am: |
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Reborn, the camera works exactly as you described and is ok here. Also tested it with another lens.
It is definetly the lens that is faulty.
Eugen |
Geowelch
Tinkerer
Username: Geowelch
Post Number: 18
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, August 30, 2008 - 04:54 pm: |
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I also have a Kiev 6C/Vega 12B combo with the same problem. I took it apart and found a part of the rather crude linkage mechanism was missing. I tried McGyvering a part for it but no luck. I've basically given up and just use the lens as a preset, which seems to work fine. |
