DIY: fixing tight focus ring

Discussion in 'Camera Building, Repairs & Modification' started by lightfox, Feb 4, 2012.

  1. lightfox

    lightfox Member

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    The focus ring on my 50mm rokkor is uncomfortably tight in the closest 1/3 of the focusing range. The lens hasn't been used in years and probably has never been serviced. I'm guessing the lubrication has degraded over time. How difficult is it to fix at home? If not, how much can I expect to spend to have a repair shop do it?
     
  2. ParkerSmithPhoto

    ParkerSmithPhoto Member

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    Love an answer, too, for my beloved Bronica SQ 110mm macro.
     
  3. E. von Hoegh

    E. von Hoegh Member

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    It's not terribly complex, you just have to disassemble the focussing helicoid, clean out the old grease, and replace it with new grease.

    I use a light lithium grease. Disassembly will depend on the lens.
    Be sure you understand what you are doing, have (and know how to use) the correct tools, and have experience working with smallish things.
     
  4. John Koehrer

    John Koehrer Subscriber

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    Not very complex? I suppose not from a parts count but.

    There are six starting points with the helical and only one is correct. A little patience is needed but you may hit the right pair first time. Or not.
     
  5. CGW

    CGW Member

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    Frankly, for a lens that common and cheap, I'd take my chances with a "new" used one.
     
  6. ic-racer

    ic-racer Member

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    I'd practice on a junk lens first. See if you can unscrew the helicoid, clean every lens surface and put it all back so it is in focus at infinity.
    Check this page, when you can do that you are ready grasshopper.
     
  7. Sethasaurus

    Sethasaurus Member

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    Or you could NOT do it the guesswork way (above) and take note of the orientation of the lens halves when you undo them (or mark a line with a pencil before you take it apart).
    :wink:

    It's also easy to take lots of pics on a cellphone camera to help remember which bits goes where.
    (You can lie out the screws next to the lens in the pattern you took them out).

    Also, Naptha (or Ronsonol lighter fluid) is a very good grease/oil solvent.
     
  8. ParkerSmithPhoto

    ParkerSmithPhoto Member

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    Wow. Don't have time for all that. I'll send it to Koh's Camera.
     
  9. E. von Hoegh

    E. von Hoegh Member

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    This is why you mark things BEFORE you take them apart. As I said, not very complex. Just observe and think before you leap.
     
  10. John Koehrer

    John Koehrer Subscriber

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    Gee whiz, I NEVER would have marked the silly thing. That's way too easy. That, by the way was sarcasm.
    Now that the pencil and scribed lines have been covered. Why didn't you mention them with your first response to the OP?
    Did you assume something like maybe someone who had never taken a lens apart would know they should use witness marks.
     
  11. pbromaghin

    pbromaghin Subscriber

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    Good lord, this is one of the most common lenses on earth. I agree. Just buy another one. That is, unless you like messing with small, delicate parts and want to learn how to do this as an academic exercise.
     
  12. dehk

    dehk Member

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    Its not too bad. I'll do it for you two if you want PM Me.
     
    Last edited by a moderator: Feb 7, 2012
  13. E. von Hoegh

    E. von Hoegh Member

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    "Be sure you understand what you are doing". I think that covers it. What the hell is your problem?
     
  14. Nicholas Lindan

    Nicholas Lindan Advertiser Advertiser

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    I found the best grease to be 'vacuum grease' - made for laboratory glassware fittings. It won't outgas (read fog the inside lens surfaces), migrate (read gooey diaphragm) or separate into oil and sludge (read seized focusing helical and an oily diaphragm). My experience with silicon (Silglide), Lithium (Lithease) and Calcium (Lubriplate) greases is that they do all three given a little bit of time.

    You can also use 'optical damping grease' but it seems to outgas a wee bit and fog lenses when the grease is new. It is probably a good idea to bake the grease first to get the last of any solvents out of it.
     
  15. E. von Hoegh

    E. von Hoegh Member

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    There's a grease called "Krytox" that is designed to not outgass. In my Nikkor lenses, the grease is nowhere near the diaphragm, unless you apply it with a grease gun. Other 35mm lenses may or may not be arranged similarly. I've had no trouble with the lithium grease hazing the glass, but I've only been using it on helicoids for about 13-14 years. The brand I have isn't Lithease, it's an instrument type grease. Again, in my lenses, the helicoid is far enough from the glass that it may not be a problem. I think perhaps the most important thing is, not to apply too much. Some lenses I've had apart are greased up like a wheel bearing.
     
  16. Nicholas Lindan

    Nicholas Lindan Advertiser Advertiser

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    That might explain it ... wait a bit longer. OTOH, there are many different lithium greases - Lithease will start to separate in 24 hours. A lot depends on the storage conditions of the lens.
     
  17. E. von Hoegh

    E. von Hoegh Member

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    The lithium grease I have is a transparent red, it's for intrument use. A friend had a big container and gave me some in a small mustard jar which of course does not have the grease manufacturer's name on it. It doesn't separate at all in the jar, but who knows what time will do to it. The lenses are stored indoors in temperate and dry coditions, but are used in temperatures from -25f to +90f. It gives a very nice low drag but smooth feel to the focussing, which in my opinion is worth cleaning the thing every 20 years or so. :smile: