Contact sheet to judge proper development?

Discussion in 'Enlarging' started by mattk, Dec 28, 2006.

  1. mattk

    mattk Subscriber

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    I think I have this right but could someone confirm...
    Last night printing a bunch of contact sheets to file some negs I noticed that some rolls of film did not produce the same level of black between the frames as others(given the exact same exposure under the enlarger). Is this an indication of improper development(or just different levels of dev)? I am trying to establish some base lines when it comes to soup time/agitation etc and would like to know if the black between the frames hold and secrets.

    Matt
     
  2. CPorter

    CPorter Member

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    If it takes longer for one film to get black through clear film, then it could indicate that you did something different that increased the fog level on the film base. Your method of development can influence the fog level in addition to age, humidity, heat of the environment the film is placed in.

    Stay consistent in your processing.

    Chuck
     
  3. CPorter

    CPorter Member

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    I meant to add that when making proofs, exposing the paper for just the amount of time to reach maximum black can tell you much about the densities of your negatives.

    CP
     
  4. jon koss

    jon koss Subscriber

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    Are they all the same type of film?
     
  5. mattk

    mattk Subscriber

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    Yes, in fact the greatest difference was noted with Ilford3200. All the other sheets are fairly close in "blackness" in the spaces between frames. The 3200 seemed more in the direction of very dark gray.
     
  6. jon koss

    jon koss Subscriber

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    I have noticed that high speed films do not print as black between frames compared to slow films, so I do not think this is abnormal. But that's just me. Can't speak for others.
     
  7. Markok765

    Markok765 Member

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    What about contrast?
     
  8. Bob F.

    Bob F. Member

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    Different films (FP4+, HP5+, Delta 100, Delta 3200, Tmax 100, etc) will have different film base + fog density between frames and will therefore need different exposure times to reach black on the contact print, though some may well be very close. You need to establish the standard printing time independently for each film to get a good black on each contact print.

    Have fun, Bob.
     
  9. jstraw

    jstraw Member

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    Any single film that consistantly fails to produce black through film base+fog indicates that you're not exposing the contact sheet long enough. If you can't get black through fB+F, then you can't get black at all. It sounds to me like you're making contact sheets designed to hide the flaws of too-thin negatives.
     
  10. Jim Jones

    Jim Jones Subscriber

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    Enlarger voltage variations can cause modest exposure inconsistancies. I use a voltage regulator with my ancient enlarger to eliminate this.
     
  11. mattk

    mattk Subscriber

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    fB+F? I can get blacks, just noticed the time required for diffrerent films since I was doing about 20 contact sheets. The film base response makes sense-should have thought of that. Each film base has its own density. I would like know what that equations is though.... fB+F

    Thank you for all the replies!
    Matt
     
  12. jstraw

    jstraw Member

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    fB+F is just a shorthand way to express "film base plus fog," which is the density of the unexposed film edge. Propper proofing time is unigue for each film/developer/light-source/paper/developer combination and even then, unique for each person. Propper proofing time is the minimum exposure required to produce maximum print density through film base plus fog.

    If your film edge is not black, there can't be any black anywhere in the frame.