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Cleaning a Sigma Zoom K-2 70-210 f/4.5

Discussion in 'Adapted Lenses' started by izzikiorage, Nov 1, 2014.

  1. izzikiorage

    izzikiorage TalkEmount Veteran

    323
    Jul 30, 2013
    Hi Everyone

    I bought a pretty nifty MD mount sigma zoom k-II 70-210 f/4.5 off ebay some time back. It's a pretty awesome lens with great bokeh and decently sharp images.

    7boQ35d.

    Now comes the problem, the glass element at the very front (facing the subject) seems to have a circular spot (oil mark type thing) in the very center. It appears purplish in color and sort of looks like the mark the lens gets if you touch the glass with oily fingers. My hunch is that it's due to this stain that I've been getting low contrast images, that lose some of their sharpness, infact the mark shows up in on the bokeh like shown below

    15466358028_ff503e38c1_c. Reigniting that fire by Amlan Mathur, on Flickr

    So the question is how can I get rid of this? Can I open up the lens without ruining it (the screws are on the side the cam mounts), what would be the easiest way to do so. Is there any alternate, like some people suggested that I keep it in sunlight or with some silica gel packs.
     

    Attached Files:

  2. xXx1

    xXx1 TalkEmount All-Pro

    Jan 15, 2013
    The front lens is typically easy to clean. It is usually held in place by screw in bezel. Find a suitable rubber stopper or something similar and press and rotate bezel away. The cleaning may be more difficult, water, isopropyl alcohol, ammonia (pure and diluted with distilled water), acetone or lighter fluid usually do the trick. Generally speaking lighter fluid has worked best for me. For cleaning cotton swabs work great, get ones with wooden handles.
     
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  3. izzikiorage

    izzikiorage TalkEmount Veteran

    323
    Jul 30, 2013
    Will give that a shot. i just tried to get the bezel to unscrew with my bare hands. Couldn't do it. Could you tell me how to use the stopper or rubber band to open this?
     
  4. xXx1

    xXx1 TalkEmount All-Pro

    Jan 15, 2013
    I don't know that particular lens but this usually works:

    Find a suitable rubber stopper (homebrew stores are great place for these), the solid kind. Its diameter should be such that it barely fits the lens. Place lens on a table and push and rotate the stopper at the same time. Most bezels come out easily.

    For smaller lenses kitchen sink plugs work great.
     
  5. izzikiorage

    izzikiorage TalkEmount Veteran

    323
    Jul 30, 2013
    Will need to find the stopper. Did try to turn the ring with my hands and a couple of other implements. I'm assuming its the ring type thing that fits over the glass and under the screw threads for attaching the filter. No luck so far.

    Will post some images to confirm whether this can actually open.
     
  6. tkoctkoc

    tkoctkoc New to TalkEmount

    9
    Nov 18, 2012
    Ontario Canada
    rubber stopper (homebrew stores are great place for these

    Please post picture of the rubber stopper? Door stopper ? Wedge type door stopper?
    Thanks
     
  7. izzikiorage

    izzikiorage TalkEmount Veteran

    323
    Jul 30, 2013

    Attached Files:

  8. izzikiorage

    izzikiorage TalkEmount Veteran

    323
    Jul 30, 2013

    Attached Files:

  9. izzikiorage

    izzikiorage TalkEmount Veteran

    323
    Jul 30, 2013
    OK, got it open. The ring was stuck or had adhesive on it. Damaged it a little getting it out. But finally opened it up and cleaned it up well. Will give it shot tomorrow when I have better light to use the lens and let you know whether I just blew it or got it right.
     
  10. xXx1

    xXx1 TalkEmount All-Pro

    Jan 15, 2013
    It is probably ok.

    Rubber stoppers are things that are used to close a bottle or jar. Like these:
    http://www.hometrainingtools.com/stoppers/c/126/

    Laboratory supplies are more expensive than other sources and lots of people use big glass bottles to brew beer or wine and so those homebrew stores are great places get 45mm-70mm stoppers.
     
  11. izzikiorage

    izzikiorage TalkEmount Veteran

    323
    Jul 30, 2013
  12. xXx1

    xXx1 TalkEmount All-Pro

    Jan 15, 2013
    These tools aren't very expensive either. I have lens spanner (about 15 USD), bezel removers are about 50 USD per set (Chinese) but stoppers work ok so I use them. I really miss that suction cup, haven't been able to find cheap ones. Really tricky tool to find is JIS screwdrivers.
     
  13. izzikiorage

    izzikiorage TalkEmount Veteran

    323
    Jul 30, 2013
    Considering that the lens cost me USD 43 I didn't want to spend all that much on tools. Did get it cleaned and working again,

    the front bezel is a little bent out of shape so does not fit as well. Any way to rectify that?
     
  14. izzikiorage

    izzikiorage TalkEmount Veteran

    323
    Jul 30, 2013
    Finally got a chance to test out the lens properly today. Seems like all is good. The front bezel is a little bent out of shape so won't fit as well as before and since it protrudes a little I can't seem to fit a filter or a lens cap anymore (would love help with this) But the quality has improved by leaps and bounds

    Sharing an image that I took today

    [​IMG]
     
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