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  1. #1
    Jeff Bannow's Avatar
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    Help with process for determining development times

    So, in the process of setting up my new darkroom I am moving from stainless steel inversion tanks to a Jobo CPP2 with lift. I have used a Jobo before and am familiar with its operation, though this particular Jobo is new to me.

    I have some Pyrocat HD that I would like to test for development time. For various reasons, I would prefer to shoot at box speed and adjust development to match. I am however a little confused on how to do this. My plan was to shoot a normal scene say 4 times, then process each one for a different amount of time and go with the one that looks good.

    I don't have a densitometer or sensitometer. I'm not exposing using the zone system. I see that Richard Ritter offers a service - Film testing - but I'm not sure if this would help me or how I would use it.

    I guess what I need is a beginner's tutorial on determining development speed.
    - Jeff (& sometimes Eva, too) - http://www.jeffbannow.com

  2. #2

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    What film will you be using and what printing process? What metering technique?

  3. #3
    Jeff Bannow's Avatar
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    Film - mostly Acros 100 and FP4+. Printing - Silver gelatin via condenser head. Metering - incident metering.

    Thanks.
    - Jeff (& sometimes Eva, too) - http://www.jeffbannow.com

  4. #4

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    Jeff,

    If you are comfortable using BTZS metering techniques, you could start with the silver times that Clay Harmon has posted here. That will put you very close to the right times for FP4 and all you would have to do is shoot and see how it goes and adjust a bit here and there.

    -Paul

  5. #5
    Jeff Bannow's Avatar
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    Never used BTZS metering, but I found some starting times that look good. I figured I could just look at the test negs on my light table, but I'm not sure if I need something more scientific.
    - Jeff (& sometimes Eva, too) - http://www.jeffbannow.com

  6. #6

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    BTZS metering is easy. Take a reading in the shadows and a reading in the bright area, subtract the low EV from the high EV and add that to 5. Thus, if your bright area is an EV 15 and the shadow area an EV 13, you have a SBR of 7 (which is "normal" in zone system terms). Then look at the times recommended for that SBR and develop accordingly. You could also look at Phil Davis's book.

  7. #7
    Jeff Bannow's Avatar
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    That doesn't sound too hard at all. My meter has a spot meter on it, I just never delved into using it.
    - Jeff (& sometimes Eva, too) - http://www.jeffbannow.com

  8. #8
    Jim Noel's Avatar
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    Your idea of shooting at box speed and altering development will likely work with the films you mention. However, many films will be underexposed by 2/3 of a stop or more if used at box speed. Since correct exposure is based on shadow values, and development primarily alters highlight values it is necessary to determine your correct EI prior to determining correct development time.
    [FONT=Comic Sans MS]Films NOT Dead - Just getting fixed![/FONT]

  9. #9
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    Clip tests.
    "Only dead fish follow the stream"

    [APUG Portfolio] [APUG Blog] [Website]

  10. #10

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    If you use BTZS to determine exposure you should use an incident meter, not a spot meter.

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