Jupiter-8 disassembly question

[Michael Fraley]

Hi,

I have two of the 'new' Jupiter-8's, the black models that rotate the aperture ring along with the focus ring. One has a stiff aperture ring, and the other has a loose aperture ring. I'd like to take them apart and either thin or thicken the lubricant to get the desired smoothness. Kim Coxon is very good at this -- he did two early silver J-8's for me and has a great website. I think the construction is different on the newer J-8's, though. He says to grasp the lens unit firmly and unscrew it from the focusing unit. I've done this on older J-8's, but on these black ones I feel like I'm forcing it, and it will break. Nothing gives. Also I read somewhere about loosening the set screws in the aperture ring and unscrewing it. Again, I am having no luck. Anyone familiar with these models and how to take them apart?

Thanks,
Michael

[Stuart Walker]

Ok, I've got one of them in front of me. It does come apart as Kim Coxon describes for the first silver finish one. Remember to grip just the very front of the lens where the filter thread is, (mine has a serrated edge to it). You may have to grip it with a rubber cloth, and hold the focus ring on the other end. It can be very tight, some Zenit Helios lenses I've disassembled have been. Make a note of how the aperure ring aligns with its index mark so that you can be sure you have tightened it together in the same place. If you remove the rings mark their position before you remove them! I seem to remember that you can reorientate the aperture ring by loosening the three screws. The points of the screws go into drilled depressions in the mating part, so you have to unscrew them enough to clear these depressions, or remove them altogether, but then they are fiddly to get back in, especially when ones eyes are getting older! I hope this helps.

[Michael Fraley]

Thanks Stuart,

It does indeed twist apart if one is determined. I didn't want to force it but removing the filter first, helped greatly.