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stiff focus ring on a Jupiter-8

Discussion in 'Adapted Lenses' started by rhoydotp, Aug 29, 2012.

  1. rhoydotp

    rhoydotp Mu-43 Top Veteran

    609
    Aug 5, 2012
    Toronto, Ont
    rpamparo
    I'm guessing it needs to be cleaned or re-lubed. Anybody here have done it by themselves? Any tip will help at this point :smile:
     
  2. the.growler

    the.growler Mu-43 Regular

    The factory lubricants in FSU lenses are notorious for drying out and solidifying over time. Fortunately, the Jupiter-8 is very easy to service. Kim Coxon's site has guides to servicing both Jupiter-3s and Jupiter-8s (they are the same fundamental design) - between the two guides, you will probably find instructions for whichever version of Jupiter-8 you have.

    http://www.pentax-manuals.com/repairs/j3service.pdf

    http://www.pentax-manuals.com/repairs/j8service.pdf

    The biggest challenge is fitting the 3 parts of the focus helix back together to give the lens block enough rearward travel to reach infinity focus. Each helix has multiple possible starting points - meshing the 3 parts together means multiple permutations, only one of which is correct. Make sure you photograph every step of the dis-assembly thoroughly, be prepared for a lot of trial and error and, if you get frustrated, put the lens aside for a day rather than trying to force something to fit. Remember, these lenses were originally assembled by hand without the benefit of any automation or specialized tools - you can do the same with enough patience.

    I find that electrical contact cleaner is an excellent de-greaser, btw. It leaves no residue and dries very quickly.

    Have fun!
     
    • Like Like x 1
  3. LegacyLens

    LegacyLens Mu-43 Regular

    99
    Apr 25, 2012
    I heard it was because whale oil was used any way to confirm that or does anybody know for sure
     
  4. rhoydotp

    rhoydotp Mu-43 Top Veteran

    609
    Aug 5, 2012
    Toronto, Ont
    rpamparo
    thanks for the link! it looks easy enough, but patience is not something that comes naturally to me :rofl:

    i'll update this thread once I muster enough courage to start doing this :biggrin: