60mm/5.6 componon in a strange mount

Discussion in 'Darkroom Developing and Printing' started by sreenath, May 21, 2007.

  1. sreenath

    sreenath Guest

    Hi All,

    A few years ago I bought a number of enlarging lenses on eBay(where
    else?).
    One of them is a 60mm componon lens. However, it has been screwed
    tightly into a much larger metal cylinder that
    has 50mm diameter, and the 50mm cylinder is threaded on the outside.

    I tried to retrieve the "original" lens so that I can use it in my
    enlarger, but it is very tightly sitting inside the 50mm cylinder that
    I could not get it out.

    Have any of you come across a mount that can accept a 50mm threaded
    lens?
    I am curious to know what this lens was used for.

    The 50mm cylinder is quite deep(thick?), about an inch, so I suspect
    it was used for focussing.

    Any information about this lens is appreciated,

    thanks in advance,
    Sreenath
     
    sreenath, May 21, 2007
    #1
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  2. Some large enlarging lenses, 150mm Rodagons at the
    least, come in 50mm mounts. They are sometimes screwed
    into 50mm->39mm reducers so they can be mounted in
    standard 39mm holes.

    This is the first I have heard of a 39mm->50mm adapter.

    It is quite possible this lens was used for other
    purposes - scientific, industrial - and hence the
    adapter.

    If the lens mount and the adapter are both anodized
    aluminum then it is not surprising they are stuck
    together.

    Try a drop of WD-40 or Liquid Plumber around the crack
    between the lens and the adapter. Rap the adapter
    sharply with a small hammer every day or so until
    they come apart.

    To take it apart faster you can try the oil &
    rap above and then boil a pan of water, stick
    the adapter end into the hot water to heat it up
    and then rapidly pull it from the water and
    unscrew. Wear gloves. Only have a 1/2" or 1"
    of water in case you drop the lens.

    It is possible the hot water trick will work with
    hot water from the sink.

    My lens, it got de wrong hoe
    Oil, rap and boil, huh!
     
    Nicholas O. Lindan, May 21, 2007
    #2
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  3. sreenath

    pico Guest

    I think Liquid Wrench would be better.
     
    pico, May 21, 2007
    #3
  4. Uh, yes, thank you. Liquid Plumber, lye,
    would be a _very_ bad choice.

    Liquid Wrench is indeed the stuff to use.
     
    Nicholas O. Lindan, May 21, 2007
    #4
  5. sreenath

    sreenath Guest

    Hi,

    thanks for all responses.

    I forgot to mention that the "original" lens has a 25mm diameter, the
    standard used by Schneider for some of its enlarging lenses.
    So this is converting a 25mm/0.5mm thread to 50mm thread with a pitch
    of approx. 1mm.

    ---
    Sreenath



     
    sreenath, May 21, 2007
    #5
  6. Nicholas O. Lindan spake thus:
    Better yet, to avoid the possibility of oily substances migrating to
    lens surfaces, I'd use acetone/lacquer thinner instead, injected with a
    syringe. This has loosened all kinds of threaded stuff for me. The rest
    of Nick's advice (several days, rapping w/hammer) is good.


    --
    Any system of knowledge that is capable of listing films in order
    of use of the word "****" is incapable of writing a good summary
    and analysis of the Philippine-American War. And vice-versa.
    This is an inviolable rule.

    - Matthew White, referring to Wikipedia on his WikiWatch site
    (http://users.erols.com/mwhite28/wikiwoo.htm)
     
    David Nebenzahl, May 21, 2007
    #6
  7. sreenath

    gr Guest

    It might be the 60mm is a wide angle lens and the mount is to allow
    additional clearance to prevent cutoff.
    gr
     
    gr, May 22, 2007
    #7
  8. sreenath

    Glenn Booth Guest

    You could also just get a new lensboard tapped for 50mm threads.I use a
    Beseler 45MXT and I keep all my lens on separate boards for quick changes.

    Glenn Booth
     
    Glenn Booth, May 28, 2007
    #8
  9. sreenath

    Ken Hart Guest

    It's possible that the lens was used in a minilab.
    My minilab has twenty different enlarger lens in various focal lengths (and
    brands), each one mounted in a barrel that fits into the lens box. The
    distance between the negative and the paper can't change, so if I want to
    print a wallet size print from 35mm, I use one particular lens; if I want to
    print 8x10 from 6x7 negatives, I use a different lens. The location of the
    lens inside the barrel eliminates the need to focus (since you can't really
    focus a minilab).
     
    Ken Hart, May 29, 2007
    #9
  10. sreenath

    darkroommike Guest

    It could indeed be a mini-lab lens, many used Schneider
    optics. The 50mm barrel could be a focusing mount. BTW the
    operator doesn't focus a mini-lab but the lab manager or
    installer can using a piece of ground glass at the easel
    position inside the printer. Most of the time the lenses
    then get locked down so that there's no need to refocus
    whenever the operator changes "setups" to print a different
    size.
    darkroommike
     
    darkroommike, May 29, 2007
    #10
  11. sreenath

    sreenath Guest

    Thanks again for the information.
    I have found a workshop nearby that will make a lens board with a 50mm
    thread in it. I will be able to use it in my enlarger.
    It may be easier to "critical-focus" with the lens thread.

    rgds,
    Sreenath
     
    sreenath, May 31, 2007
    #11
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