Cosina-Voigtlander 15mm f4.5 Super-Heliar LTM Helicoid CLA with pictures!

j-dogg · Jul 5, 2022

Let me preface this, there will be a few of these over the next couple of days as I have a couple weeks of time off to take care of my girlfriend while she recovers from a hysterectomy, now that she is up and moving around I can knock some repairs off the docket I've been hoarding for this time off. Right now, it's one of these CV 15mm f/4.5 LTM lenses that permanently stays on my Leica IIIc. Some time ago, it got soda spilled on it. That was a death sentence, it turns almost solid unless I break it free. Then after a couple minutes, it hardens again. Now it's time to do something about it.

This is a work in progress [now completed] but should have it done soon so I will update this as I work on it.

j-dogg · Jul 5, 2022

The first thing to do, is remove the front optical block. The optics on this lens are split into two blocks, a front and rear with the aperture in between. Remove the front with a lens spanner tool and grab the outer edges for the block. The inner divots are for the individual elements, which this copy did not need done. It won't take much to get it off so be gentle.

j-dogg · Jul 5, 2022

Next, you want to get the rear optical block off. Getting the optics out of the way will prevent them from being damaged or smudged from handling the lens. Start by removing the lens mount. These are 4 screws and note the top one aligned with the top of the lens that screw has a small indentation on it, pay attention to this because when you go to reassemble it that alignment has to be maintained or the lens will not mount correctly. Once you get that off, there is a set screw on the rear optical retaining ring. Loosen it but don't remove it, turn counter clockwise and it will come loose. The rear block is held into place by this and you will also notice a shim pop out if it's an M39 LTM model, this goes between the block and the lens, don't lose it. Set the blocks aside.

j-dogg · Jul 5, 2022

Now we can focus on getting to the helicoids. There are three screws holding the lens petal on, remove them. Flip the lens over and there are two alignment posts that have two screws each holding them down, remove those. Make an alignment tick mark on the back side for the aperture block, I'll explain this later. There's also a circlip on the top, remove this too and be careful to not warp it.

Make note of this tick mark and how it is aligned with the top of the lens, as well as the screw holes relative to the two alignment post holes, you will need this later

j-dogg · Jul 5, 2022

Remove the aperture pin bracket

j-dogg · Jul 5, 2022

Remove the aperture assembly. This is all one block like the optical blocks and it unscrews and drops out of the bottom of the lens. Set this aside and don't let anything get inside it like hair or FOD. Remove the second retaining circlip.

j-dogg · Jul 5, 2022

This is the tricky part, remove the aperture ring. Behind this ring is a ball bearing with nothing holding it in place but what I surmise is a magnetic plate that screws in from the side. Do not lose this thing. The ball bearing is behind the actual aperture markings. It pulls straight up, pull it slowly. Secure the ball bearing and then pull up on the focus ring. It has a key in it that lines up with this screw, wiggle it up and off.

j-dogg · Jul 5, 2022

Remove this large screw. It is the infinity focus stop for this lens. Use a small set of pliers and don't gorilla force it off but gently loosen it and use a screwdriver to do the rest. The brass helicoid drops out of the bottom too like the aperture assembly did. You are now basically completely disassembled, mechanically

j-dogg · Jul 5, 2022

Use naptha or lighter fluid to remove the old grease. This fine pitch helicoid is the focusing helicoid. It only has one key for it to go on, so you don't have to worry about screwing it on the wrong way and things being misaligned.

j-dogg · Jul 5, 2022

Run the helicoids through and check for old grease or any hitching in the focus mechanism. If all is well, apply the new helicoid grease. My weapon of choice is Japan Hobby Tool PTFE grease, I believe it's #10. I like a happy median between one-finger focusing and not going anywhere. Reassemble the helicoid and pay attention to the alignment of the dowel pin relative to the stop point. You want the pin to be as close to the center of the opening as possible, mine has a fair amount of use so there's actually a small indentation of where the metal has been hitting it, I used that to align it. Once you are satisfied with the alignment, install the limiting dowel pin.

Also note the two holes, the big one is the ball bearing and the small one is for the set screw to hold the tension plate in

j-dogg · Jul 5, 2022

Next you will install the ball bearing and the tensioning plate, this goes on the inside of the lens. Note the length of the screw, there's only one screw on the lens that short. If you use any other screw it will interfere with the aperture ring and you will be able to mount it but not rotate it so make sure the screw is not protruding on this side. Very carefully, install the ball bearing. It should stay in place on it's own but don't make any sudden movements.

j-dogg · Jul 5, 2022

Reinstall the second circlip that is uniform thickness all around. Next, install the aperture ring, for ease of install slide the aperture numbers over the area where the ball bearing is. It slides down like the focus ring did.

j-dogg · Jul 5, 2022

Your lens should look like this now

j-dogg · Jul 5, 2022

Now, you will install the aperture assembly from the bottom. It screws into place. Remember your alignment tick mark on the bottom side.

j-dogg · Jul 5, 2022

Almost there! Next, install that aperture pin bracket. Do not use screws that are too long or the aperture ring will not rotate. Then, install the first circlip and pay attention to the wider part relative to the same sized divot on the aperture ring, line them up and install the circlip

j-dogg · Jul 5, 2022

Flip the lens over and install the two alignment posts with the alignment tick marks aligned. Then, install the lens petal with three screws. Note the top of the petal has a white dot to align itself with the rest of the lens top. Install the front optical block.

j-dogg · Jul 5, 2022

Now, reinstall the lower optical block. It just drops in, don't forget to put the shim between the block and the lens, then screw in the retaining ring and tighten the set screw. Check for play in the rear element. If none, install the mounting ring, note the alignment indentation and how it lines up with the top alignment axis. You're all done now!

Cosina-Voigtlander 15mm f4.5 Super-Heliar LTM Helicoid CLA with pictures!

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