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Thread: BTZS Metering Question

  1. #11

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    Re: BTZS Metering Question

    Sorry Ian, I missed that you asked about development times with respect to SBR, not the Zone System.

    Below is a chart for the same film/developer combination. Note that for SBR 7 - which corresponds to a scene of normal contrast - the recommended development time is the same as previously given for N development.


  2. #12

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    Re: BTZS Metering Question

    Here is another graph which shows how effective film speed changes as we modify development time. This chart uses Zone System notation.

    Again, this chart is only for HP5+ in D-23 1:1 at 70 degrees F, but the principles are fairly universal.



    Note that film speed is around 250+ for N development, goes down 200+ for N-1 development, etc.

    Each film/developer combination will have its own characteristics, but this is nothing new: back in the 1970's Minor White suggested that we modify film speed by 10-15% with each level of expansion and contraction. He wasn't the first to discover it either. Note that since one f/stop equates to 50%, 10 or 15% amounts to a fairly modest adjustment in film speed: a fraction of an f/stop.

    With a scanning workflow, contrast can be increased ad infinitum. This eliminates the need for over-development which increases grain. If in addition we avoid scenes which require dramatic contraction, life becomes much easier. In photojournalism we have to bring back the photo whatever it takes. With Fine Art photography we can pre-select scenes which match the tonal scale of our medium.

    If we shoot this film at ISO 200 and rely on the scanner's wide dynamic range which gives us an automatic N-1 contraction, we can easily accommodate scenes of 1 more f/stop than usual. If we use an Infra Red viewing device and develop by inspection, each negative gets its own treatment, correcting any mistakes made in the field, which do happen, in spite of all this BTZS and Zone System... stuff.
    Last edited by Ken Lee; 29-Dec-2016 at 07:35.

  3. #13

    Re: BTZS Metering Question

    Develop by inspection? No problem, we'll fix it on the scan?

    I guess we just pour powder chemistry into the water "until it looks good more or less."

    Yikes.

    Sent from my 0PJA2 using Tapatalk

  4. #14

    Re: BTZS Metering Question

    You're consulting charts on exposure versus development but you have no idea of the development time until after the exposure.

    Sounds more like Before The Zone System.

    Sent from my 0PJA2 using Tapatalk

  5. #15

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    Re: BTZS Metering Question

    Quote Originally Posted by Ken Lee View Post
    Here is another graph which shows how effective film speed changes as we modify development time. This chart uses Zone System notation.

    Again, this chart is only for HP5+ in D-23 1:1 at 70 degrees F, but the principles are fairly universal.

    Note that film speed is around 250+ for N development, goes down 200+ for N-1 development, etc.

    Each film/developer combination will have its own characteristics, but this is nothing new: back in the 1970's Minor White suggested that we modify film speed by 10-15% with each level of expansion and contraction. He wasn't the first to discover it either. Note that since one f/stop equates to 50%, 10 or 15% amounts to a fairly modest adjustment in film speed: a fraction of an f/stop.

    With a scanning workflow, contrast can be increased ad infinitum. This eliminates the need for over-development which increases grain. If in addition we avoid scenes which require dramatic contraction, life becomes much easier. In photojournalism we have to bring back the photo whatever it takes. With Fine Art photography we can pre-select scenes which match the tonal scale of our medium.

    If we shoot this film at ISO 200 and rely on the scanner's wide dynamic range which gives us an automatic N-1 contraction, we can easily accommodate scenes of 1 more f/stop than usual. If we use an Infra Red viewing device and develop by inspection, each negative gets its own treatment, correcting any mistakes made in the field, which do happen, in spite of all this BTZS and Zone System... stuff.

    I find this explanation containing a lot of knowledge. Of course, a too contrasty illumination can be an unnecessary complication to generate an art we visualize. Anyway I feel attracted by the challenge from very contrasty scenes like night photography. Then the N+/- comes short, as you point, using compensating development techniques to get sound results is another war

  6. #16
    Kirk Gittings's Avatar
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    Re: BTZS Metering Question

    Quote Originally Posted by Ken Lee View Post
    Below is a graph generated for me by Fred Newman of the View Camera store, using the BTZS Plotter software. It shows recommended development times for different treatments according to the Zone System. (N is the development we would give for subjects of normal contrast range.)

    The graph is specifically for Ilford HP5+, tray-developed by me in my darkroom in D-23 1:1 at 70 deg F.



    You can see that the recommended time for N development is around 9 minutes and 20 seconds. For N-1, it's just over 7 minutes... etc.

    This graph was made by Fred exposing sheets of film under an enlarger with a step-wedge, then me doing the development, then Fred measuring the results with a densitometer. Thus, it is independent of any camera, shutter or lens. Because I developed the film, it was custom tailored to my method of agitation, my water, my thermometer, etc.

    I shared the Zone System graph here since you know that system, but the Plotter software delivers many graphs, such as how effective film speed changes with changes in development time, contrast, SBR, etc.

    BTZS generates a lot of charts with great precision, but the results are not essentially different from what we get by following widely published time/temperature charts. If the differences were substantial, we'd have to wonder why.
    Did you pre-soak for this test?
    Thanks,
    Kirk

    at age 70:
    "The woods are lovely, dark and deep,
    But I have promises to keep,
    And miles to go before I sleep,
    And miles to go before I sleep"

  7. #17

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    Re: BTZS Metering Question

    Quote Originally Posted by Kirk Gittings View Post
    Did you pre-soak for this test?
    Hi Kirk -

    Yes, as I remove the sheets from their holders, I place them into a water bath and pre-soak for 3-5 minutes.

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