Switch to English Language Passer en langue française Omschakelen naar Nederlandse Taal Wechseln Sie zu deutschen Sprache Passa alla lingua italiana
Members: 71,836   Posts: 1,582,437   Online: 704
      
Page 2 of 3 FirstFirst 123 LastLast
Results 11 to 20 of 22
  1. #11
    Ole
    Ole is offline
    Ole's Avatar
    Join Date
    Sep 2002
    Location
    Bergen, Norway
    Shooter
    Large Format
    Posts
    9,282
    Blog Entries
    1
    Images
    31
    Ed,
    The flash from the tape isn't static electricity. It's triboluminescence - an entirely different phenomenon. And it doesn't hurt, except when you try to spell it.

    I've seen "lightning tracks" on film used in very dry weather - in Africa, not Norway. The marks on Robert's film could well be that. The start/stop with irregular spacing is about what I would expect...
    -- Ole Tjugen, Luddite Elitist
    Norway

  2. #12

    Join Date
    Sep 2002
    Location
    Just north of the Inferno
    Shooter
    Medium Format
    Posts
    750
    Images
    27
    It can't be stress marks. The negs are intact looking (no dents, dings, etc.) and the problem occurs with two seperate cameras. O.k. Both are Nikons but they are almost 30 years apart in age. So it can't be that.

    Although the point about visible discharge is worth noting here. We are talking about film rated at 6400. The same shots with 400 or 100 speed would be pitch black. This could be a regular occurance, but only a problem when I am running such funky film through the cameras.
    Official Photo.net Villain
    ----------------------
    [FONT=Comic Sans MS]DaVinci never wrote an artist's statement...[/FONT]

  3. #13
    Les McLean's Avatar
    Join Date
    Oct 2002
    Location
    Northern England on the Scottish border
    Shooter
    Multi Format
    Posts
    1,610
    Have you considered processing marks? I've seen some strange marks on films after they have been processed in deep tanks in labs. I've shot Delta 3200 at speeds from 800 to 25000 ISO and have never had any strange effects such these. I have good contacts in Ilford UK so I'll send your original post with the attachment to the technical department to see what they make of it. I'll keep you posted.

  4. #14

    Join Date
    Sep 2002
    Location
    Just north of the Inferno
    Shooter
    Medium Format
    Posts
    750
    Images
    27
    Thanks Les.

    It could be processing marks I guess, but the rolls were shot over a period of time and developed at different times.

    Then again who knows.

    I am sure though that static caused by dry-air is not much of a problem up where you are at.

    Official Photo.net Villain
    ----------------------
    [FONT=Comic Sans MS]DaVinci never wrote an artist's statement...[/FONT]

  5. #15

    Join Date
    Feb 2003
    Posts
    4
    What way does your shutter open? Horizontally or Vertically? This might be light leaking through shutter blades at odd times or with exposure to bright light sources. Just a small amount going through, enough to expose the high speed film and not enough to expose the slower film.

  6. #16

    Join Date
    Sep 2002
    Shooter
    Large Format
    Posts
    4,530
    Aha...I finally rememebered where I have seen this, those look like emulsion scratches caused by the felt on the cartridge. Usually a piece of dirt gets caught in the felt and when you rewind, specially at high speed the dirt scratches the emulsion.
    You can tell because it is intermitent but it is on a straight line. Of course, this happens right down the middle of the roll, if it was at the edge then it would not be the curse of the photo Gods....:P

  7. #17
    Ed Sukach's Avatar
    Join Date
    Nov 2002
    Location
    Ipswich, Massachusetts, USA
    Shooter
    Medium Format
    Posts
    4,520
    Images
    26
    Quote Originally Posted by OleTj
    Ed,
    The flash from the tape isn't static electricity. It's triboluminescence - an entirely different phenomenon. And it doesn't hurt, except when you try to spell it.
    ...
    Oh. First time I've heard of triboluminescence. In what way does it differ from a static electricity discharge? - In three words or less ...
    Carpe erratum!!

    Ed Sukach, FFP.

  8. #18

    Join Date
    Sep 2002
    Shooter
    Large Format
    Posts
    4,530
    tribo...what?..what the heck is that??? never heard of this, please explain!

  9. #19

    Join Date
    Sep 2002
    Location
    Just north of the Inferno
    Shooter
    Medium Format
    Posts
    750
    Images
    27
    Is Triboluminescence what you get when you rub two trilobites together?
    Official Photo.net Villain
    ----------------------
    [FONT=Comic Sans MS]DaVinci never wrote an artist's statement...[/FONT]

  10. #20
    Ole
    Ole is offline
    Ole's Avatar
    Join Date
    Sep 2002
    Location
    Bergen, Norway
    Shooter
    Large Format
    Posts
    9,282
    Blog Entries
    1
    Images
    31
    Triboluminescence isn't electric, it's chemical (well - physical really, but not electrical). It refers to a substance giving off light when subjected to mechanical stress. It's a lot more common than you'd think, but the light is so weak it's rarely noticed. As far as I know, all types of sticky tape do this to some extent. But we tend to notice those we tear in the darkroom.

    I had a feeling I would be asked to explain this...
    -- Ole Tjugen, Luddite Elitist
    Norway

Page 2 of 3 FirstFirst 123 LastLast


 

APUG PARTNERS EQUALLY FUNDING OUR COMMUNITY:



Contact Us  |  Support Us!  |  Advertise  |  Site Terms  |  Archive  —   Search  |  Mobile Device Access  |  RSS  |  Facebook  |  Linkedin