marks on negative

Discussion in 'B&W: Film, Paper, Chemistry' started by thebanana, Oct 28, 2005.

  1. thebanana

    thebanana Member

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    I need some advice/help. I'm relatively new at processing MF film (B+W), and on several occasions I find small crescent shaped marks on my negatives when processing is complete. They appear randomly across the whole strip. Could they be caused by something I'm doing while winding the undeveloped film onto the reel? I use Nikkor SS reels and tank. Is there something else going on here? Cheers.

    John
     
  2. PeterDendrinos

    PeterDendrinos Member

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    Could they be greasy finger prints from handling the film?
     
  3. Bob F.

    Bob F. Member

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    Any chance of a scan? Is there physical damage at the crescents as in a buckle in the film? Are they light or dark (light suggests physical obstruction, dark suggests a light leak)? Do you get them with commercially processed film (if yes then it is most likely something in the camera rather than the processing).

    Cheers, Bob.
     
  4. Monophoto

    Monophoto Member

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    When loading stainless reels, it is necessary to cup the film slightly so that the width of the film fits between the inner dimensions of the reel. If you go beyond cupping and actually crimp the film, you can sometimes get crescent-shaped marks after the film has been processed.

    Have you ever tried loading a reel with the light on, using a sacrifical roll of film? This can be an educational process because you can actually see what is happening at the same time that your fingers are providing tactile feedback.
     
  5. panchromatic

    panchromatic Member

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    My guess is buckleing of the film when loading it, I myself have done this a few times when I first started loading metal reals with MF.
     
  6. rbarker

    rbarker Member

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    As stated, the little crescents are being caused by kinking the film during loading. That's usually a result of either bending the film too much, edge-to-edge, or having uneven tension between the reel and the "feed" hand, resulting in a push-pull sort of motion between the two. These problems are probably most prevalent during the early part of the roll, when the grip of the reel clip is tentative, and it is more difficult to maintain even tension.

    If you are shooting 35mm, my suggestion would be to get a couple of Hewes reels. The Hewes reels use a cross bar at the center that has little fingers that catch the sprocket holes. This design provides a more positive grip on the film, making it easier to maintain even tension. The level of tension should be slight, but consistent. Too much tension will tend to distort the edge of the film, pulling it out of the spiral track toward the center of the reel.

    The second suggestion, which works for both 35mm and 120, is to use the thumb and index finger of your "feed" hand at the edges of the film to guide the film from the "feed" hand, gently pulling the film through your fingers. Rest those fingers on the edge of the reel to get the right spacing and the minimal cross-curve needed.
     
  7. Blighty

    Blighty Subscriber

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    The crescent shaped marks are caused by the film buckling when being loaded onto the reel. If you've a problem getting the film onto the reel (MF can be a real PITA for this), try locating a piece of discarded 120 film in the groove below the take-up point. This stops the film buckling downwards into the reel. When the film has been 'engaged' on the reel, you can remove the discarded bit. Obviously I'm making a massive assumption in that you're using Paterson type reels!!
     
  8. Blighty

    Blighty Subscriber

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    Ooops! I've just re-read the original thread. Please take no notice of my previous entry.:0
     
  9. thebanana

    thebanana Member

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    I appreciate the advice. I sort of suspected that it was related to getting the film on to the reel. Practise, practise, practise, I guess! Thanks all.
     
  10. Charles Webb

    Charles Webb Member

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    These little marks have a name, they have been called "Oyster Shells" since the introduction of roll film. The same name applies to prints mishandeled during development. They are easily created when handeling larger sheets of single weight papers, like 11x14 or 16x20. Once they appear, they are there, only a new sheet of paper properly handled will not show them.

    Charlie......
     
  11. lee

    lee Member

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    I always heard those marks called "Murder Marks".

    lee\c
     
  12. Quinten

    Quinten Member

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    I've had the exact same problem with TriX (never with APX somehow) these pitch black spots. I do use Paterson reels, what reels would be better for those thanks? And are they still availeble?

    Thanks!
    Quinten