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Problem(s) with my 25mm CCTV lens

Discussion in 'Adapted Lenses' started by albert_ang, Jul 17, 2012.

Top Rated
  1. albert_ang

    albert_ang Mu-43 Regular

    26
    Jun 5, 2012
    Melbourne, Australia
    Hi,

    I just bought the 25mm f1.4 C-mount lens for my Olympus OMD.
    The problems I have are:
    1. The focusing ring is very stiff. When I turned it clockwise, instead of the rotating focusing ring, it unscrewed the lens. Does anyone else have this issue?

    2. The lens failed to focus something any object closer than 2-3m. But it has no problem focusing at infinity. Is my lens defective?

    Thank you!

    Regards,
    Albert
     
    albert_ang, Jul 17, 2012
    #1
  2. DeeJayK

    DeeJayK Mu-43 Hall of Famer

    3,355
    Feb 8, 2011
    Pacific Northwest, USA
    Keith
    I don't have a 25mm c-mount (yet), but I've experienced this with my 35mm lens to some degree. Is it something that happens every time you turn the ring, or is it just an occasional thing? For me, it's the latter and I chalk it up to a minor inconvenience.

    2-3 meter close focusing distance definitely seems abnormal. That would make the lens all but unusable to me. Of course these c-mount lenses are often designed to be used in security cameras and the like, so maybe it's not necessary to design it with a short close focusing distance in mind. This makes it difficult to tell if this is an issue with the design of the lens or the construction of your particular example.

    I think if it were me I'd look into returning the lens if possible.
     
    DeeJayK, Jul 18, 2012
    #2
    • Like Like x 1
  3. madmaxmedia

    madmaxmedia Mu-43 Veteran

    346
    Feb 20, 2010
    Seems defective or at least suboptimally assembled. Which specific 25mm lens is it?
     
    madmaxmedia, Jul 18, 2012
    #3
  4. Hyubie

    Hyubie Unique like everyone else

    1,393
    Oct 15, 2010
    Massachusetts
    Herbert
    I assume this is similar to those 35mm eBay copies, of which I have one. Any chance that the sort of extension tube is attached? Try removing that, if it is indeed attached.
     
    Hyubie, Jul 18, 2012
    #4
  5. albert_ang

    albert_ang Mu-43 Regular

    26
    Jun 5, 2012
    Melbourne, Australia
    Yep, it's the cheap ebay cctv lens. I didn't put the extension ring. It's stiff at ALL times. I guess, I got the rubbish one.
     
    albert_ang, Jul 18, 2012
    #5
  6. mister_roboto

    mister_roboto Mu-43 Top Veteran

    637
    Jun 14, 2011
    Seattle, WA, USA
    Dennis
    Mine had a stiff focus ring- I took it apart and carefully lubed the parts (no grease on elements).

    I think it's the only lens I've ever fiddled with and taken apart where I didn't need any tools :wink:
     
    mister_roboto, Jul 18, 2012
    #6
    • Like Like x 1
  7. hinata76

    hinata76 Mu-43 Regular

    130
    Jun 21, 2012
    Singapore
    Strange..im using a 35mm CCTV lens..indeed..if turn to ur right it will unscrew the lens..but not that stiff..have not gotten my 25mm yet..maybe u can ask the seller for a replacement? or diy using lube?
     
    hinata76, Jul 19, 2012
    #7
    • Like Like x 1
  8. albert_ang

    albert_ang Mu-43 Regular

    26
    Jun 5, 2012
    Melbourne, Australia
    I just tried to disassemble it and re-assemble again - and now it works!! Maybe the upper and lower part was not tightly screwed previously.

    Took few shots - it has the worst purple fringing I have ever seen in all my lenses. Bokeh looks unique.
    Well, can't complain too much for quality control and image quality on $18 lens :rolleyes: 

    Thanks everyone for the response. :smile:
     
    albert_ang, Jul 19, 2012
    #8
  9. DeeJayK

    DeeJayK Mu-43 Hall of Famer

    3,355
    Feb 8, 2011
    Pacific Northwest, USA
    Keith
    Great news. Now you can add "lens technician" to your resumé. :wink:

    Indeed the cats-eye/ swirly bokeh of these little lenses is part of their charm, I guess. As for the fringing, that can be cleaned up pretty quickly if you're using the latest version of Lightroom.
     
    DeeJayK, Jul 19, 2012
    #9
    • Like Like x 1
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