The Russian Jupiter 8 lens was manufactured by KMZ Optics for use with the Kiev rangefinder --- a copy of the more expensive Contax camera. Because of the impressive optical quality of the lens, it was subsequently mass produced and made to fit all rangefinder cameras with Leica (Leitz Camera of Germany) thread mounts. Even 50 years after its original production, the Jupiter 8 retains its reputation as an affordable alternative to the comparable Zeiss lenses. Because of its age, however, yours may require light servicing to function at peak performance.
Grip the base of the lens, near its mounting thread, and twist it counterclockwise to remove it from the camera. Set the camera body aside.
Grasp the front of the lens, directly in front of the aperture selection ring, and twist it counterclockwise to remove the front lens unit. Once loosened and removed, there will be two pieces: the front lens unit (with two shim rings threaded on) and the focus unit.
Remove the three small screws around the base edge of the focus ring with a micro screwdriver. Set them in a plastic container for safe keeping. Pull the focus ring (engraved with distance scale) away from the focus unit and set it aside. Another ring, affixed by screws, will be revealed.
Loosen and remove these three additional screws and set them in the plastic container. Remove the ring and set it next to the focus ring.
Flip the focus unit so that the mount threads face up. Remove the three screws that secure the ring surrounding the threads and set them in the plastic container. Lift off the first thin ring, then the thicker lens mount ring beneath it. Set them aside the other rings in the order you removed them.
Remove the small guide pin from the base end of the focus unit. Set it in the plastic container.
Dampen the tip of a cotton swab with lighter fluid and gently clean dried grease and dirt from the threaded areas of the focus unit. Use additional swabs, also moistened with fluid, to clean the different rings you removed from the unit. Allow them to air dry.
Apply a small dab of metal polish to a polishing cloth. Gently rub the polish onto the outer metal parts (focus unit rings and aperture ring) and let them sit for several minutes. Buff off with a dry portion of the polishing cloth.
Dip the tip of a fresh cotton bud into the silicone-based synthetic grease. Apply the grease to all threaded areas of the lens.
Moisten a lens cleaning tissue with a few drops of leans cleaning solution. Starting from the centre of the glass, gently wipe the rear element in a circular motion, moving out toward the edges. Repeat for the front element.
Reassemble the focus unit by performing the reverse of the steps described in the first section. Ensure that you replace the guide pin before replacing and securing the other rings or the lens may not focus correctly. Once the focus unit is reassembled, ensure that the two shims are threaded onto the lens unit and rethread it into the focus unit.
A jeweller's loupe may be helpful for those with poor eyesight. It may also make removal of the tiny focus unit screws easier. Make sure that your work area is well lit and free of debris, as you will be working with many small parts.
Disassembly and service of any camera lens is a very involved, detailed process. If you do not have prior experience with optics or camera lenses, you may wish to consult a professional repairperson.