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  1. #111
    Stephen Benskin's Avatar
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    Quote Originally Posted by CPorter View Post
    With d-76 1:1, which is quite a straight-lined curve in my process, gamma can be easily determined, however, finding gamma, is not required to find development times.
    First of all Gamma refers to a specific methodology. I'm assuming you mean slope or gradient.

    Itís of no consequence whether anyone does or doesnít use contrast index to determine the contrast of their film. It is an analytical tool. Just another tool in the toolbox. It is one of many approaches. I believe that looking at a problem from only a single perspective wonít give you the whole picture. Come at anything from different directions and problems and answers that at first may not have been evident will reveal themselves.

    Using some form of gradient is also helpful in communicating. A single number offers a lot of information. Just like placing ISO in front of the film speed. It's placement communicates to everyone that all the steps in the ISO Standard were followed. That way others can understand how the testing was performed, the implications of the results, and how to do the testing themselves to confirm the results. Just like they taught us in science class.

    But donít anybody kid themselves. Contrast determination is about film gradient. It's inherent in all the methods including the Zone System. Itís basically about input and output, and you can't have an output unless there's something put in. The Zone system uses a base density of 0.10 over Fb+f. The highlight is at 1.35 over Fb+f. The filmís density range is 1.25. The exposure range between the exposure that created the shadow density and the exposure that created the highlight density is 7 stops (2.10 logs). The input is 2.10 logs. The output is 1.25.

    1.25 / 2.10 = 0.595

    Without knowing the exposure range (input), it would be impossible to gauge the degree of processing. Try and describe how to do Zone System testing to someone without explaining the part about input.

    The standard model in tone reproduction has an input of 2.20 logs minus some flare 0.30 to 0.40, and an output of 1.05 NDR.

    1.05 / 1.80 = 0.583

    The negative density range (output) of the tone reproduction model is different only because the range of the input is effectively smaller than the Zone System model. What this shows is that the film contrast is the same for both models and the different output values are only the result of using different input values.

    Another way to look at is to think of the film density range and film contrast as two separate elements. The density range is a result of a given input range at a particular film contrast. The film contrast represents the degree of development. A smaller input luminance range will result in a small density range without a change in the film contrast. The film can have a certain contrast even though there is only a single point of density.

    If you find the two points that make for a 1.25 negative density range with litho film will have under Ĺ stop of input. If itís only about density range, than the results would look the same from a pictorial test, that required 7 stops to reach a NDR of 1.25, and a litho film, that required ~1/3 stop to produce a NDR of 1.25.

    Without considering the input value as well as the output value, the picture on how the process works is incomplete. The real question should be which method has the best agreement with use over the broadest set of conditions. The first piece of evidence can be that Alan Ross has identified a problem with the a fixed density range method with greater than average luminance ranges.

  2. #112
    Stephen Benskin's Avatar
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    Quote Originally Posted by CPorter View Post
    I simply cannot subscribe to the idea of there always being a 1 or 1 1/3 stop of flare present just because I have a lens on my camera..........flare is certainly a consideration, it is never a consistent thing, but I believe it has been my experience that the image contrast and subject contrast can, not always, be quite close (with quality multi-coated lenses), but is never perfectly matched either.
    We can't rely on anecdotal evidence. Look at all the way people saw the world before the Enlightenment. That's why there's the scientific method.

    I've never asked anyone to accept anything I say based only on my word. I've included references, uploaded seminal papers, and presented facts and equations that illustrate how it all works. There is a preponderance of scientific evidence out there. You just have to take the time to look for it because it's hiding in plain sight.

    From Wikipedia: Anecdotal evidence

    In science, anecdotal evidence has been defined as:

    "information that is not based on facts or careful study"[4]
    "reports or observations of usually unscientific observers"[5]
    "casual observations or indications rather than rigorous or scientific analysis"[6]
    "information passed along by word-of-mouth but not documented scientifically"



    From Wikipedia: Scientific Method

    In the 20th century, a hypothetico-deductive model[9] for scientific method was formulated (for a more formal discussion, see below):

    1. Use your experience: Consider the problem and try to make sense of it. Look for previous explanations. If this is a new problem to you, then move to step 2.
    2. Form a conjecture: When nothing else is yet known, try to state an explanation, to someone else, or to your notebook.
    3. Deduce a prediction from that explanation: If you assume 2 is true, what consequences follow?
    4. Test: Look for the opposite of each consequence in order to disprove 2. It is a logical error to seek 3 directly as proof of 2. This error is called affirming the consequent.[10]

    A linearized, pragmatic scheme of the four points above is sometimes offered as a guideline for proceeding:[46]

    Define a question
    Gather information and resources (observe)
    Form an explanatory hypothesis
    Test the hypothesis by performing an experiment and collecting data in a reproducible manner
    Analyze the data
    Interpret the data and draw conclusions that serve as a starting point for new hypothesis
    Publish results
    Retest (frequently done by other scientists)

  3. #113
    CPorter's Avatar
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    Quote Originally Posted by Stephen Benskin View Post
    But donít anybody kid themselves. Contrast determination is about film gradient. It's inherent in all the methods including the Zone System.
    Yes, I am referring to the slope of the straight line of a curve when a straight line is actually present, that's all.

    I follow you on all that, no problem-----CI is easily determined ZS useage or not, I only am stating a fact that CI in and of itself, is of little use to me in being fluid with ZS and of making good negatives and evaluating contrast.
    Last edited by CPorter; 02-18-2012 at 06:31 PM. Click to view previous post history.

  4. #114
    CPorter's Avatar
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    Quote Originally Posted by Bill Burk View Post
    I think you read me wrong because I think we are in agreement.

    Thanks Bill, that was a clever way to get your message across better, and it worked. Did I read once that you use graded paper? I use VC paper, so Chuck probably won't be wanting to use Bill's paper!

  5. #115
    Stephen Benskin's Avatar
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    Quote Originally Posted by CPorter View Post
    I follow you on all that, no problem-----CI is easily determined ZS useage or not, I only am stating a fact that CI in and of itself, is of little use to me in being fluid with ZS and of making good negatives and evaluating contrast.
    Just because you don't personally use some form of average gradient, doesn't mean it can't be used in a discussion or that any point made using some form of average gradient isn't valid because you don't use it.

    Tell ya what. Explain to me using the example below how you go about determining your development. It's a family of curves with Fb+f zeroed out. I've even marked out a 1.20 NDR. Or upload an example of your own showing how you do it.

    Click image for larger version. 

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    Last edited by Stephen Benskin; 02-18-2012 at 08:15 PM. Click to view previous post history.

  6. #116
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    Quote Originally Posted by Stephen Benskin View Post
    Just because you don't personally use some form of average gradient, doesn't mean it can't be used in a discussion or that any point made using some form of average gradient isn't valid because you don't use it. That would just be insane.
    Oh, there's no need to be threatened by little old me.......................I'll tell you what, first, prove in my posts where I indicated that it can't be used in discussion because I pernsonnally don't use it and and that a point made regarding average gradient is not valid because I don't use it. It's not in post #101, #107 (this is where I acknowledge there is nothing wrong with CI or using it in the ZS or whatever), it's not in #108, and it's not in #113. You don't get something for nothing in this world . You do that and and admit how horribly wrong you are with these assertions and I'll provide you with an answer, gladly.

  7. #117
    Stephen Benskin's Avatar
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    That's just an attempt to avoid answering the question. Bill and I have explained how gradient is an intrinsic part of contrast determination even if the gradient value isn't determined. This should be obvious to anyone taking the discussion seriously. Yet, you have maintained a position that it's somehow possible to determine contrast without it.

    I'm simply asking you to support your statement, otherwise it's just another unsubstantiated anecdotal claim. Put your money where your mouth is, or maybe you're intentionally acting in bad faith, wasting everyone's time, and attempting to derail this thread. Don't they call that being a troll?
    Last edited by Stephen Benskin; 02-18-2012 at 09:56 PM. Click to view previous post history.

  8. #118
    Bill Burk's Avatar
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    Quote Originally Posted by CPorter View Post
    Did I read once that you use graded paper? I use VC paper, so Chuck probably won't be wanting to use Bill's paper!
    Right... Bill has two choices: Grade 2 and Grade 3. I picked a paper, Galerie, over 30 years ago that is still available. How many people can say that?

  9. #119
    CPorter's Avatar
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    Quote Originally Posted by Stephen Benskin View Post
    That's just an attempt to avoid answering the question. Bill and I have explained how gradient is an intrinsic part of contrast determination even if the gradient value isn't determined. This should be obvious to anyone taking the discussion seriously. Yet, you have maintained a position that it's somehow possible to determine contrast without it.

    I'm simply asking you to support your statement, otherwise it's just another unsubstantiated anecdotal claim. Put your money where your mouth is, or maybe you're intentionally acting in bad faith, wasting everyone's time, and attempting to derail this thread. Don't they call that being a troll?
    I see your ego and your arrogance won't let you go where I want you to go, therefore I won't go where you want me to go. I have your answer, but I don't feel compelled to prove anything to you, nobody should, as this will do nothing but feed your ego, so believe what you want to believe. If the consensus in this thread believes that I am a troll, I'll leave it, in the mean time, get on with it.

    I take the discussion seriously, nothing I've said implies a denial of the importance of gradient in determining contrast (those are your words). The only position that I've maintained is that determining CI is not integral to using the ZS, anyone who chooses can determine this for themselves. Please note where I have maintained that it's possible to determine contrast without gradient.

  10. #120
    Bill Burk's Avatar
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    Chuck, I believe you want to make a strong statement about the simplicity of the Zone System. I think a position such as that is easy to defend.

    Steve, I believe you want to generously share technical details "from the other side" and discuss things the Zone System glosses over.

    It's not wrong to say "this doesn't pertain to me," but sometimes it causes a squelching effect in a technical thread. I got the feeling that was what happened here. A friend of mine used to have a rule: If you don't like something, don't just tell me to stop it. Suggest something you like in its place.

    I like to say the Zone System is so easy to get your head around and easy to get immediate results from.

    But I am interested in delving in the details that were overlooked to see if they can be "folded into" Zone System practice, and I want to have you both involved in the discussion.



 

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