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Message |
    
Ronnies
Tinkerer
Username: Ronnies
Post Number: 15
Registered: 09-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, August 23, 2010 - 02:32 pm: | 
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Hi,
I've recently acquired one of the Zebra style CZJ Sonnar 135 f/3.5 lenses with an aperture mechanism that's stuck wide open. I know the mechanism works and is just 'gummed up' since I can open and close it using the long rod mechanism if I take the mount off. Trouble is I can't seem to work out the way to fully disassemble the lens to get at the aperture mechanism to clean it. I've seen links for dismantling the later MC version but not the Zebra one.
Does anyone know how to help me please?
Thanks !
Ronnie |
Prasanna
Tinkerer
Username: Prasanna
Post Number: 59
Registered: 10-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, August 25, 2010 - 07:21 pm: |
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Praktica User's web site has the cross section diagram for this lens. I have one in Exakta mount that had a similar problem with the aperture as well as fungus in the rear group. In my sample I found that the rear group was easy to remove as it was mounted on a sealed cylinder. Removing it it exposed the aperture from the rear. Thus I could reach and clean both the lens and the aperture. I think the front group is also, similarly, mounted in one cylinder. I hope this helps. |
Ronnies
Tinkerer
Username: Ronnies
Post Number: 16
Registered: 09-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, August 28, 2010 - 08:11 am: |
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Prasanna,
Thanks for the response. I did manage to find a service manual for CZJ lenses on Rick Oleson's site and it includes a great mechanical cross section of the model I have. You are right, the rear element just unscrews inside its tube once you get the rear internal lens hood off. With the rear element out I was able to use cotton buds to swab clean the aperture and it now seems to work fine. This was a very simple job to do with no real tricky disassembly or reassembly.
Thanks again !
Ronnie |
Zuikopath
Tinkerer
Username: Zuikopath
Post Number: 9
Registered: 05-2010
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, June 17, 2011 - 09:59 am: |
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I'm having a problem with this lens getting the front element out - I have loosened the front ring with the two notches in it and it has unscrewed about 1.5mm but now it has stopped and turning it doesn't bring it any further out...?
Any top tips on this procedure...?
Many thanks |
Barnum
Tinkerer
Username: Barnum
Post Number: 204
Registered: 10-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, June 17, 2011 - 11:57 am: |
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I do not have actual experience of this particular lens, but others with a similar problem have been slightly distorted by a blow at some time. It does not take much of one to cause this problem |
