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Dennisdietz
Tinkerer
Username: Dennisdietz
Post Number: 6
Registered: 08-2008
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, November 19, 2008 - 04:55 pm: | 
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Anyone ever disassemble one of these? I'd appreciate any experience with this. The aperture lever that connects to the ring seems jammed about halfway there (beyond f/22). I can't seem to get anything apart regardless of how many screws I remove.
Thanks,
Dennis |
Dennisdietz
Tinkerer
Username: Dennisdietz
Post Number: 7
Registered: 08-2008
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, November 19, 2008 - 06:03 pm: |
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OK, so I am able to get the front lens assembly off, the collar that acts a stop, camera end, for the hood has reverse threads to the lens assemble. You must remove that first then finish unthreading the front element.
The distance scale has three set screws that remove to expose 6 phillips screws. I can see the ends of these screws going through into the back section of the lens with the rear element. I believe removing those screws (they currently seemed to be glued) would remove whole back assembly. This would expose the screws for the stops that keep the lens traveling straight during focus.
What I don't know:
How to get to the outside of the blade assembly. My problem lies in the lever that sets the aperture stop using the ring on the lens. 180 degrees from that assembly is where the camera aperture lever connects. This mechanism works fine. There seems to be something jammed or bent one the aperture ring mechanism, below where I currently have access or can see.
Any thoughts as to further disassembly to access the outside of the blade mechanism? Any chance it just slides out the way a Nikon 28/35/50 does?
Also, warning, the aperture clicks uses a tiny detent and ball bearing. Don't loose this if you disassemble the lens.
Thanks |
Dennisdietz
Tinkerer
Username: Dennisdietz
Post Number: 8
Registered: 08-2008
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, November 24, 2008 - 11:33 am: |
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For the life of me I cannot figure out why the lens is doing this. It worked fine when I got it but there was a little dust in one of the inner elements that I felt may be causing lack of contrast and sharpness. Thinking it may be on the inside of the rear element (the rear elements move for focus) I removed the mount and lifted straight off. After inspection it seemed I would be better off to go in from the front so I re-attached the mount to work on it again another day. In doing so, the mount seemed to seat fine but as I started to tighten the screws, I noticed a little tension like the screws were pulling the mount down. I stopped and took it back of, realizing the aperture ring had lifted a little and the ball was not seated properly. Fixed that and reassembled. At that point I realized the aperture ring was would not turn past f/8 (it had worked before I mucked with it). Pulled aperture ring off again and realized the linkage to the blades from the ring was very stiff. Gently moved it hoping to re-seat or loosen the problem and now the aperture ring lever mechanism is really stuck. The blades still work fine using the camera aperture lever but not the lens ring lever.
It is possible I did not have something seated properly when I replaced the mount the first time, thus forcing the ring mechanism forward, bending or jamming something. The blades are obviously fine it seems since the camera linkage lever works the blades fine.
Any thoughts as to how to access the outside of the aperture/blade mechanism on this lens? |
Dennisdietz
Tinkerer
Username: Dennisdietz
Post Number: 9
Registered: 08-2008
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, November 28, 2008 - 10:21 am: |
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Fixed: A follow up.
So, I finally figured out how to access the aperture mechanism. If the front element is removed, three screws are visible on the end of the inner "baffles"- don't know what else to call them. If you remove these three screws, the aperture mechanism/blade assembly and one inner lens element will lift straight out. Indexing of this is not critical.
In my case, the problem was that I somehow moved the aperture ring linkage to far and the stops and that part of the blade mechanism then bound with the post from the camera aperture linkage. With the assembly free, all I had to do was move the camera linkage lever to open the blades fully, then work the other lever stop past the obstruction. Very simple fix actually adn I might have been able to do it with out disassembly, but did not know until I saw how everything fit together.
Good news is that removing the aperture mechanism allowed me to clean the haze and dust from the inside of the rear most element, now the lens seems a little more sharp and the contrast is improved.
I did not take photos but hopefully my descriptions are sufficient if one is in the process of disassembling the lens.
Best,
Dennis |
Msiegel
Tinkerer
Username: Msiegel
Post Number: 69
Registered: 03-2008
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, November 28, 2008 - 11:47 am: |
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Hi Dennis,
I always like to read the end of a story. I am sure your description will helpful to others (not to me as I don't have the lens).
Anyway thanks for sharing your "adventure" here.
Martin |
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