Hello,
Here is a brief guide for partial CLA of the 2.3/35 Auto-Takumar that I put together based on the advice from forum members ‘Kozlok’and ‘niceshot’ and my own experience. Perhaps it will prove useful for others.
Step 0: Tools needed. I used a set of vacuum pads and a TD-55 JIS screwdriver set (shown in the photo), and a needle-nose soldering iron, a rocket air blower and lens cleaning supplies (not shown in the photo). Four of the screws needed repeated heat cycles with the soldering iron before I was able to unscrew them.
Step 1: Unscrew the front element (the left most part in the attached photo). This step is straightforward, and I used the largest vacuum pad.
Step 2: Remove the truncated cone front part that now looks like a large lens hood (the second part from the left in the photo). It is important to mark its position before moving it in either direction, because it can be used to fine-tune infinity focus.
Inside the cone, there is a single retaining screw (the hole for it is visible in the photo towards the bottom near the silver thread) Before attempting to unscrew the cone part , I removed the retaining screw completely to make sure that it had made an imprint (a small metallic dot) and that I could see this imprint with the cone still in place. Once I verified that the imprint was present and visible, I unscrewed the cone and removed it.
Step 3: Remove the focusing ring (bottom center part in the photo). There are three screws at the top that attach the ring to the inner part of the focusing helicoid (the brass ring at the top of assembly shown in the top center). Once these are unscrewed, the ring can be simply removed.
If the lens mount has already been removed, as shown in the original post by ‘Petrodelta’, what is left is the assembly shown at the center top in the attached photo.
This assembly is very similar to focusing mechanisms found in other manual focus lenses. There is the brass focusing ring; a limiting screw that restricts the helicoid movement between infinity and MFD; two guide rails, each held in place by two screws; and an outer barrel that attaches the helicoid to the lens mount.
Because the 3-in-1 oil had started to react with the grease in the helicoid (as I was afraid would happen), I had to take the helicoid apart to clean it completely before relubing. This step might not be necessary, though, and partially unscrewing the helicoid (just take care to not turn too far) and applying fresh grease to the exposed portions of the threads might be sufficient. However, there was no oil on the aperture blades or the inner lens elements, so I did not have to take the lens completely apart.
My lens had been serviced before, and I could rely on the existing markings while reassembling it. There are many good tutorials online (albeit for different lenses) that provide some guidance as to what should be marked before taking the helicoid apart.
I removed the two guide rails (the two screws holding one of the rails are visible in the photo under the 95 mark) to remove the outer barrel and clean the oil that had made its way there. Then I took the helicoid apart and cleaned it in lighter fluid. The barrel and the helicoid had already been marked, so I just had to keep track of the marks while taking the pieces apart.
After cleaning and relubing, I followed these steps in reverse to reassemble the lens.
Regards,
Last edited by sjp; 07-12-2020 at 07:17 AM.
Reason: Removed redundant images.