What is this?

Discussion in 'B&W: Film, Paper, Chemistry' started by NER, Dec 18, 2004.

  1. NER

    NER Member

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    The first image is a reflective scan of an unprocessed 8x10 negative cropped to remove the notch code and altered in PS (using the "equalize" adjustment) to reveal the mysterious pattern as clearly as I can manage using that bizarre and unfamiliar tool.

    The second image is the same as the first, except that it is presented in "grayscale" mode.

    The third image is the same as the second, except that it is further injured by another affliction of the "equalize" tool.

    I suspect this is the emulsion itself. The pattern is clearly visible on inspection of the film, although it seems impossible to discern any difference in the thickness of the emulsion by visual examination alone. The pattern reveals itself without variance in the processed negative as well. I do not think this phenomenon can be attributed to the processing agents or steps used, precisely because the pattern appears in the UNPROCESSED negatives, and the materials and methods that were used work satisfactorily with all the other emulsions I have ever tried. I discount for now the possibility that this can be the anti-halation coat because the pattern remains after processing which normally removes that coat. The film was refrigerated.

    I have written to the manufacturer about this. While I wait for a reply, I wonder if any reader of this note has encountered anything similar before or has a different theory about the nature or cause of this strange (and for me unprecedented) finding? Thanks.
     

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  2. rbarker

    rbarker Member

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    I'm unclear on the purpose of doing the scans, Norman, particularly in reflective mode. Are you having trouble with similar patterns showing up as variations of transmission density in processed negatives with this emulsion batch?
     
  3. NER

    NER Member

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    The reflective mode scan was made because the pattern shows best when the unprocessed film is scanned in that manner. For a processed negative, the pattern shows (although less distinctly) with a regular transparency scan. The answer to your second question is "yes." More importantly, the variations show in the prints from affected negatives. This is by no means an anomaly due to the scanner I have. To illustrate, the first scan below is an unmanipulated scan of a negative of the emulsion in question. The second image is the first scan adjusted using the PS equalize tool.
     

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    Last edited by a moderator: Dec 18, 2004
  4. rbarker

    rbarker Member

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    Ouch! Obviously (to me at least), a "manufacturing defect", but I'm not sure what would cause the anomoly. It looks like something (improperly mixed, or contaminated emulsion components, perhaps?) being pushed along by the rollers in the coating process, but in a chattering sort of way. I'm curious to hear what the manufacturer has to say.
     
  5. Neal

    Neal Subscriber

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    Dear Norman,

    Please post when you receive an answer from the manufacturer.

    Neal Wydra
     
  6. KenM

    KenM Member

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    They almost look like drip marks....as if the emulsion was still wet, and the sheet was tipped up, causing the emulsion to 'run'...

    Very odd.
     
  7. Maine-iac

    Maine-iac Member

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    The film hasn't been through multiple airport security scanners, has it?
     
  8. wfwhitaker

    wfwhitaker Member

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    I can definitely see the Virgin Mary in your film defect! What a wondrous miracle! You should immediately put it on Ebay to show your appreciation to the Almighty!

    Then go have a cheese sandwich....

    Cheers
     
  9. NER

    NER Member

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    Yes, they look exactly like drip marks. These marks appear only on the emulsion side of the film. In the processed negative, the densities across areas of uniform value vary with the pattern, suggesting that the emulsion is alternately thick and thin. As far as I know, the film has not been subjected to any treatment that might reasonably account for the pattern. It is not due to the processing (the pattern appears in the UNPROCESSED negative, and shows up in negatives whether processed by tray or tube). It occurs only with this particular run of film, i.e., emulsion number, and does not occur with other films - different films - processed identically. It is not a problem with the scanner. The only plausible explanation I can think of is a manufacturing defect. I will report the manufacturer's response. Thanks for your interest and opinions.
     
  10. NER

    NER Member

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    Hi Will. That's an interesting idea ...
     
  11. djklmnop

    djklmnop Member

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    The only time I've seen anything like that is if there is an overconcentration of Photo-Flo. But I doubt this has anything to do with it.
     
  12. NER

    NER Member

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    No, that is not the culprit here. The pattern is evident in the unprocessed film right out of the box.
     
  13. Ian Grant

    Ian Grant Subscriber

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    Looks remarkably like faulty anti-halation coating on the rear of the negative.

    Some manufacturers have used a strong green coating. Efke 5"x4" PL50 which I've just started using has a layer of coating on the back of the film that actually dissolves during processing.

    If you can tell us the manufacturer then that might help pin point the problem, also how old is the film and how has it been stored.
     
  14. NER

    NER Member

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    The film is not old - its expiration date is in 2007. I do not think the anti-halation coat can be at fault here because the pattern remains in the processed negative. I'm not sure what the cause is. It may be something in my processing, although I don't think so because the pattern is seen on the unprocessed film, I haven't seen this or any similar pattern on any other unprocessed film I have ever inspected, and because the materials and procedures I used on these occasions are the same that I've used for years with other films and I never seen this problem occur with those other films after processing. Nevertheless, I hold open that possibility for now. I do not want to name the film or manufacturer at this time because doing so might unfairly discredit one or both. I have written to them and I have received some preliminary responses, but the holidays now intervene, so I do not expect a final answer from them until January.