Jupiter-3 Lube Job

[Brian]

Jupiter-3's are about the best buy in fast fifties for the Leica mount. The best are from the early 1950s, and this lens is no exception.

But like any 50+ year old lens, lubricants dry-up and the action is anything but smooth. This one was very uneven.

This is an easy job, you need some solvent such as Ronsonol, jeweler screwdrivers, and Lithium grease from the local hardware store.

[Brian]

The optics module simply unscrews from the focus mount.

[Brian]

Three small, easy to lose set screws hold the focus ring on. Remove them, and put them carefully in something like an ice-cube tray. "usually" all three set screws are the same size. On this lens, and a few others I've worked on, they are different sizes. Keep them in order. Use the "M" as the start position if you need to keep the screws in separate bins for re-assembly. I did not, and discovered after-the-fact that they were different.



Under the focus ring you will find one set screw holding the focus mechanism into the mount, or three set screws on later (~1957 and newer). Three is better!

Remove the set screws. The focus mechanism will unscrew from the solid-piece mount.

[Brian]

Move the focus to the Infinity Position, RF cam fully extended. SCRIBE the two pieces of the helical, as shown.




Remove the screws, one on each side, that ride in the guide rail. These screws hold the two-part helical together.

[Brian]

Unscrew the inner helical.



Clean the helicals with Ronsonol, Isopropyl Alchohol, or other solvent that you are confortable with.

You also need to flood-clean the outer helical mechanism that controls the near/far focus.



The focus ring rides on that black rim. You want that ring to turn smoohtly. This one was horrible.

[Brian]

I clean with Ronsonol, and also use an ultrasonic cleaner for the inner helical.



Apply the grease, a little dab will do it on a Good J-3. I've seen a couple that require more than others. This amount proved to be too much, and I swab the excess off after screwing the helicals back together. I back them off, and use a Q-Tip to wipe the excess.



The inner helical has multiple starting points, and only one of them is correct. That's why we scribed the marks before disassembling. Sometimes the marks will be there already from initial assembly.

[Brian]

At this point, put all the screws back in order. Screws for the guide rails first; screw the focus mechanism back into the one-piece mount. Put the Set Screw(s) back to hold in the helical. Put the focus ring back on. In the end, all should line up as before: Distance reference point, Distance Scale on the Focus Ring, and Reference Dot for the aperture.

Screw the optics module back in and the reassembly is complete.



See my other threads on adjusting focus for the Jupiter-3.