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Steve Roberts
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, April 26, 2006 - 07:13 am: | 
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Hi All,
I have an f2 55mm Auto Takumar that I need to dis-assemble to cure sluggish aperture blades. The only two screws I can find are on the rear flange that butts up against the camera body. These only move a fraction of a turn and cause the focussing to become stiff. I can see no other way of getting the lens apart. Any ideas, please? Just to clarify, this is the Auto Takumar that needs the aperture to be opened manually prior to exposure via a lug on its side.
Best wishes,
Steve |
George Welcher
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, April 27, 2006 - 09:07 am: |
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Sadly, you can't get to the aperature blades from the back. You have to go in from the front. Lens construction varies, and my experience has been with a couple of screw mount Pentacon lenses. Is this a screw mount lens, by any chance?
At any rate, here is a generalized procedure. First, you will need to unscrew the bezel around the front element, using some sort of friction tool, like a large rubber stopper. Set the lens to infinity first. Document everything you do (digital camera with macro setting is useful here), and take measurements, especially lens base to filter ring at infinity. A set of calipers is best for taking measurements. You should see some screws holding the focus ring to the focus helix. Remove the focus ring. Record the distance from lens base to front edge of the lens element assembly. The lens assembly itself should unscrew from the helix giving you access to the aperature and linkage. You may need to rotate the focusing helix to clear an alingment groove. Record how many turns (using index marks helps). There should be no need to remove any lens elements from the lens assembly.
Be sure to clean the linkage to the pin or blade protruding from the mount, as this is often the source of sticky aperatures.
Reassemble being sure to reset lens edge to base distances as recorded, otherwise your lens may not focus to infinity, and your distance scale will be off.
Good luck! |
Steve Roberts
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, April 28, 2006 - 02:23 am: |
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Hi George,
It is indeed a screw mount lens - 42 x 1mm, presumably the same as your Pentacon lens. I'll go in from the front as you suggest and see how I get on. I've encountered the issues with helixes and multi-start threads in the past, so I won't be surprised if I don't get it right first time on reassembly!
Thanks very much for your advice,
Steve |
Steve Roberts
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, May 31, 2006 - 02:40 am: |
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Here's an update - I found that there's actually no need to get involved with the focussing helix. I removed the front and rear lens assemblies, followed by a deeply recessed threaded retaining ring. Removing this allowed the aperture assembly housing to come out through the front and I could then set about dismantling and cleaning it (I use carbon tetrachloride). Reassembling the blades was a test of my dexterity and patience, but using the thin metal ring/shim to hold the blades in position on the front slotted piece was a big help. I then offered up the front piece and assembled blades to the body with the fixed holes that the blade dowels locate in. Attention must be paid to the correct location of the two holes that are threaded to take the aperture blade lever that runs the length of the lens.
Hope this may help others with the same lens.
Steve |
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