Dev time question ...

Discussion in 'B&W: Film, Paper, Chemistry' started by karthik, Feb 16, 2011.

  1. karthik

    karthik Member

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    Suppose we have two films that are stated to be of the same speed. Assume that the
    developer, dilutions, temperature, agitation procedure, etc. used by the manufacturer
    in determining film speed are identical for the films.

    Question: What, if anything, can be inferred from the difference in the standard
    developing time suggested for the films by the manufacturer? (Of course, for the same
    developer, dilution etc.)

    Thanks --- Karthik
     
  2. Christopher Walrath

    Christopher Walrath Subscriber

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    A very vague question. Sounds like homework. But we definitely need a little more detailed info. I do, anyhow.
     
  3. karthik

    karthik Member

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    Vague - yes. Homework - no. Just curious.

    I was wondering what influences the time taken by the same developer to produce a particular density in different films, keeping factors like dilution, temp etc. the same. I am not thinking of any particular films. And I have no way of knowing that a manufacturer's testing methods are consistent across all films.

    For instance, it is conceivable that conventional grain and tabular grain differ in the speed with which the latent image sites react to the developer. Or it might depend on the proportion of different halides in a film? Or some physical characteristic of how the emulsion was coated onto the base?

    I of course realize it is not going to be determined by some single easily stated quantity/process. Nor would this knowledge make much of a difference in using either film.
     
  4. tkamiya

    tkamiya Member

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    I predict a heated argument in about page 10....
     
  5. michael_r

    michael_r Subscriber

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    Definitely argument material. I would guess there are many potential factors, including the thickness of the emulsion coating, the way the crystals were "grown", shape, size, whether or not the emulsion is "silver rich" versus dye rich, etc. Perhaps even the degree of hardening.
     
  6. MattKing

    MattKing Subscriber

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    This sounds like the sort of question one might investigate if one was trying to "reverse engineer" a film.

    It is an interesting way to approach it.

    I might hazard a guess that the question of sensitizing dyes might come up.
     
  7. karthik

    karthik Member

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    I guess it is not argument material after all. Too hypothetical, no way to support/refute any claim one could make. I was hoping someone would mention references (books/online) for this sort of thing.