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Thread: Zone Placement

  1. #31
    Stephen Benskin's Avatar
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    Quote Originally Posted by espadrew View Post
    The goal is to carry the subject luminance through to the paper.
    That is what the curve examples are about. How do the values move through the process. In this particular case, from the subject to the film illustrating a common misinterpretation of the interpretation of the illumininace range.

    I'll be posting at least one example of a four quadrant reproduction curve to place it in context.

  2. #32
    Stephen Benskin's Avatar
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    Quote Originally Posted by markbarendt View Post
    Nope, no religion.

    Math and physics are precise, art and language are not.
    Tone reproduction can be define and is a science. Making a photogaph and how it all comes together is an art. I don't think talking about how one works diminshes the other. They complement each other, and I've found I have greater control over the outcome the more I know. Why do people think there's a need to remind everyone the photography is an art form?

    in a standard contrast scene that spacing is true.
    I'm not sure what you mean by that.

  3. #33

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    Too much is often made of sensitometry "error terms". As long as we understand the lack of precision in testing, and that real world factors such as flare can affect results, there is still value to what I'd call "simple" or even "naive" testing - for example the typical film speed and development test methodology we find in Adams and some other books - ie, shoot a card, develop, measure densities, plot densities (y-axis) versus negative exposure (x-axis). It's usually good enough.

    I'd also like to add that rather than trying to determine absolute characteristics in testing, I find plotting curves (made under the same testing conditions) useful for determining relative characteristics of different films. I always try to emphasize this when I post any kind of test. Two similar films might have different curve shapes, for example. Ansel himself said characteristic curves are more revealing when they are compared, as opposed to being looked at in isolation as some sort of absolute sensitometric descriptor.

    Don't take this the wrong way Stephen I always enjoy your posts as they are interesting and well thought out.

    Michael
    Last edited by Michael R 1974; 09-08-2011 at 02:08 PM. Click to view previous post history.

  4. #34
    Stephen Benskin's Avatar
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    No offense taken. I agree with you're saying. I just like talking about theory. This usually means focusing on the finer points. For example, there's nothing wrong with the different methods of exposure determination (eg Zone System speed testing), I just like to make a distinction between them and film speed determination.

    If you distill down this thread into a practical testing procedure, then I would have to say, when doing in camera Zone System testing for contrast determination, meter Zone V and open up two stops. Find the exposure that falls 1.05 to 1.10 over 0.10 over Fb+f. Or know that if continue to use the traditional approach where you open up three stops and use 1.25, that it will still give you the correct contrast for the film, it doesn't represent the negative density range that will be produced.

  5. #35
    RPC
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    Quote Originally Posted by Stephen Benskin View Post
    It's common usage.
    Could you point me to a documented example?

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    Wait now I'm confused... but I like the distilled version (if I'm reading it right):

    So can we talk about the difference between the two approaches:

    1. Target 1.05 over .1 over fb+f, opening two stops over metered

    2. Target 1.25 over .1 over fb+f, opening three stops over metered

  7. #37
    RPC
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    Quote Originally Posted by markbarendt View Post
    If there is no difference between a zone and a stop, then there is no reason to use the word zone. If you want to talk with precision just stop using the word zone.
    A stop refers to a specific exposure change, a zone a specific exposure level. Zones are a stop apart.

  8. #38
    Stephen Benskin's Avatar
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    Quote Originally Posted by RPC View Post
    Could you point me to a documented example?
    Personally, I don't like using Zone terminology as a general rule. I kind of had to in this thread. Yuck.

    First when I said common usage, I meant something more along the lines of common vernacular. Anyway, I've attached two documents that I think is what you are asking for.

    One is a page from Photographic Materials and Processes by Strobel et al. The other is an internal CI chart from the R&D department at Kodak.

    As the CI chart is sort of connected with the concepts of this thread, I have a challenge to present. Anyone know how the CI values were produced? What were the factors involved? Bonus points for an analysis of any strengths or weaknesses of the model.
    Attached Thumbnails Attached Thumbnails Contrast Indexes - Kodak.jpg  
    Attached Files

  9. #39
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    Quote Originally Posted by Stephen Benskin View Post
    Tone reproduction can be define and is a science. Making a photogaph and how it all comes together is an art. I don't think talking about how one works diminshes the other. They complement each other, and I've found I have greater control over the outcome the more I know.
    I don't disagree, in fact I would encourage learning more.

    Quote Originally Posted by Stephen Benskin View Post
    Why do people think there's a need to remind everyone the photography is an art form?
    My point is not that photography is an art.

    My point is that "1-stop = 1-zone" is only true where there is a normal brightness range scene, where the film is exposed normally, developed normally, and zone 2 paper is used for the print. Change the contrast of the film (expand/contact) or the paper grade and the portion of the negative that gets printed changes, the 1:1 relationship is lost.
    Mark Barendt, Ignacio, CO

    "We do not see things the way they are. We see things the way we are." Anaïs Nin

  10. #40
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    Quote Originally Posted by RPC View Post
    A stop refers to a specific exposure change, a zone a specific exposure level.
    Those are very reasonable thoughts

    Quote Originally Posted by RPC View Post
    Zones are a stop apart.
    The paper defines where the zones land.

    Zones run from pure black "0" to pure white "X" on paper. That is true regardless of the paper grade, all the zones exist regardless of how hard or soft the paper may be.

    A harder paper will print a shorter contrast range, fewer stops from the negative, than a normal paper. A softer paper will print more stops from the negative.

    Minus film development allows us to fit more stops from the scene onto a normal paper, plus development helps us fit fewer stops from the scene onto the normal paper.

    Regardless of how much of the negative is printed, there are still ten zones available on the paper.

    Regardless of how many stops existed in the original scene, there are still ten zones available on the paper.
    Mark Barendt, Ignacio, CO

    "We do not see things the way they are. We see things the way we are." Anaïs Nin

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