Zone Placement

Discussion in 'B&W: Film, Paper, Chemistry' started by Stephen Benskin, Sep 7, 2011.

  1. Stephen Benskin

    Stephen Benskin Member

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    This example, I hope, helps demonstrate a point of photographic theory. The attachment contains two examples of different Zone placements. Graph A produces a negative density range of 1.25 and Graph B produces a negative density range of 1.05. Both examples use the same film curve.

    Question: Which example has the correct representation? Why?
     

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  2. ic-racer

    ic-racer Member

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    Is there a correct one? That has always been one of my criticisms of various Zone systems. Are the zones on the negative? Are they on the paper? Are they in the scene?

    I'm curious to see your answer. I actually try to keep the word "Zone" out of my posts and avoid posting in threads with "Zone" in the title, because I don't think there is a definition of the term that everyone agrees with. The reason I read this one is I saw your name on it and am interested to see the response :smile:
     
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  3. DREW WILEY

    DREW WILEY Member

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    It's all relative to what expectations and parameters you set for your own workflow based upon a specific film and development regimen, and how it looks in your preferred print medium. There are no
    hard rules. The Zone System is nothing more than a kind of shorthand for labeling normal dev time verus
    expansion, versus contraction etc. Practitioners often place Zone II at the threshold of desired shadow detail in the original scene, and Zone VII at the upper limit of highlight containing texture; but that's based on average conditons. Films differ; and besides, how much of the toe and shoulder of the film
    you recover can be altered by things like split grade printing on VC papers all kinds of other tricks. I
    personally tend to visualize the film curve itself and meter placement of the values on that; but that
    takes some experience. The Zone System eases you into the concept. But its all based on personal
    testing to determine what you expect from it.
     
  4. markbarendt

    markbarendt Subscriber

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    Okay, I'll take a SWAG;

    If film curve remains constant it is because development remains the same.

    So the placement change is caused by a camera exposure variation.

    B would be correct because zone V actually lands at .6 +/- which is considered "normal" contrast.

    A might be considered overexposed.
     
  5. markbarendt

    markbarendt Subscriber

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    And,

    A will represent a larger chunk of the scene on film, specifically seeing farthur into the shadows.
     
  6. Bill Burk

    Bill Burk Subscriber

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    The one on the left marks off one stop per zone, while the one on the right marks off less change in effective film plane exposure per zone in the shadows. I'd have to guess the one on the right is compensated for flare.

    Now. Strike out IV and write II in its place on both graphs. Relabel all the zones accordingly. This would give the result of "placing your shadows on Zone IV".

    Does that make things "better"?
     
  7. ROL

    ROL Member

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    No – and that is both the usefulness and beauty of the (God forbid I say it) "System". You decide where tone placements will be according to your personal visualization and ultimate interpretation of the print.
     
  8. Bill Burk

    Bill Burk Subscriber

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    I have to admire the electronics engineers who decided the "Zones" for resistors and capacitors.

    They spaced the different values according to a set of nominal values that, given the manufacturing tolerances, statistically assures you that when you pick up the next higher part in the series, you will get a part that makes a difference.

    We should have designed the Zone System that way.
     
  9. Stephen Benskin

    Stephen Benskin Member

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    I don't want to give everything away just yet. I didn't say "correct one" but a "correct representation." The question concerns the interpretation of data, and specifically in this case, contrast. Creating a test wedge and plotting a film curve is just the beginning. The key is in the interpretation of the data, and a large part of that is having a good grasp of certain principles and asking the right questions.

    To be more specific about the aims, the paper is a grade 2 printed on a diffusion enlarger. According to The Negative, Zone VIII density should be at 1.35 for a negative density range of 1.25. ANSI defines a grade 2 paper as having an LER of between 0.95 and 1.15 for an average of 1.05.

    Mark is right in that the two curves are the same. In fact, they are drawn from the same set of data, eliminating any question about variations in development or differences in curve shape. The scene's luminance ranges are also identical in both examples, so it isn't about how different situations can be interpreted through the knowing placement of Zones.

    There isn't any direct relationship between Zones and specific negative densities except for Zone I and Zone VIII and that can really only be claimed for in camera testing. Technically with exposure, you can only place one value accurately (and that point has to be tested to be known). All other points fall accordingly depending on a number of factors. It's sometimes called place and fall and the concept is used by the Zone System. This is the concept that these two examples are about. Is the way we think the system works actually reflect how it works? Are people getting what they think they are getting from testing? How good can any testing be if the data is misinterpreted?

    Bill is zeroing in on the cause, but he needs to take it further and discuss the implications, and Dale is asking the right questions.

    We are looking at two different things in each of the examples. There's the film curve created by exposure to a contacted step tablet, and there are points of exposure from a "scene" superimposed on top of it. This is an important distinction. What does the x-axis represent?
     
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  10. DREW WILEY

    DREW WILEY Member

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    I find the comparison between the two graphs relatively meaningless without further specification.
    One represents a relatively "thin" negative, the other a relatively "thick" or dense one. Which one
    works bests depends how you are printing. We don't even know whether you are talking about a
    standard neg or a stained one, of whether you are aiming for a high-key print or a contrasty one.
    I always preferred aiming for Grade 3 paper; but that's even gone out the window now that VC papers have gotten so good. Besides, different brands of papers differ in contrast and can be affected
    by dev variables and toning. Like I said, it's all relative, unless you choose to make a religion out of
    the Zone System like Minor White did.
     
  11. Bill Burk

    Bill Burk Subscriber

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    I'm guessing the left hand is the perfectly spaced theoretical or planned Zones superimposed on actual film curve, while the right hand is the result where the predictions landed. There is compression in the shadows, which could lead to disappointment if you were counting on them being where you wanted.

    A better system might be one where Zones are "wider" in the shadows.
     
  12. Stephen Benskin

    Stephen Benskin Member

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    The two film curves are identical. The luminance ranges for each example is from Zone I to Zone VIII or seven stops. Both exposures are keyed to Zone I. Seems to me that if the film in the two examples is processed to the same contrast index, has the same exposure placement, and is shooting the same scene, the results should be the same. Since they don't seem to be, there's something else at work here.
     
  13. Kirk Keyes

    Kirk Keyes Member

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    Aren't the "zone" differnces just the result of paper choice? CI is the same, it's the paper LER that's changed.

    If the two papers are similar in curve shape and don't have big differences in toe and shoulder, the two "negs" should print very similarly.
     
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  15. markbarendt

    markbarendt Subscriber

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    But zones don't equal stops. The reason they are called zones is to differentiate them from stops.

    So how are the zones being defined?

    Hey, what about condenser versus diffuser.
     
  16. markbarendt

    markbarendt Subscriber

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    I was thinking similarly but zone V falls at different points on the two curves.

    I wonder per chance if they are different film's?
     
  17. Kirk Keyes

    Kirk Keyes Member

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    Zones don't have to equal stops - look at situations of N-plus and N-minus developments. The zones are how the tones are percieved in the print.

    And condenser vs diffuser question will have similar effect as printing with different papers.

    As long as what you call zone V prints at what you decide zone V in your print will be, then you have a match.

    If your CI stays the same, and your subject brightness range varies, then the paper LER must change to match.
     
  18. Stephen Benskin

    Stephen Benskin Member

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    You can of course adjust the paper LER to fit the negative density ranges, but that's assuming that the both the negative density ranges in the examples are realistic.

    All the conditions on the subject and film/processing side are identical. Shouldn't the values in both examples then be the same?

    Doesn't this only leave the possibility that one of the interpretations of the exposure scenarios are in error? Remember what I said earlier, "the key is in the interpretation of the data, and a large part of that is having a good grasp of certain principles and asking the right questions." What principle is missing? I also hinted to focus on what the x-axis represents. Bill has it.

    That is exactly the difference between the two, although I wouldn't use the term "perfectly spaced" as it implies an ideal. The film curve is produced by contacting a step tablet made up of equally space densities. This produces a graphic depiction of how the film will respond to specific exposure values. The problem comes when interpreting how the values from a scene will interact with the curve. Any optical system will change the relationship between the tones of the original scene and the exposure values of its optical camera image through the mechanism of flare. Flare compresses the apparent scene luminance range. For a one stop flare factor, an original scene with a luminance range of seven stops will become an illuminance range of six stops at the film plane. As flare affects the shadows more than the upper tones, the distribution of the exposure values in the reduced exposure is irregular compressing the lower values and having little affect on the higher values.

    So, which one of the examples do you think is the best representative of the actual exposure process?

    How would not factoring in the influence of flare affect the interpretation of the contrast of the negative using the method of determining the negative density range? What about the two different aim values for the negative density range? They can't possibly be both be right for the same paper grade? Can they?

    Does this example tend to strengthen or diminish the validity of the negative density range method of contrast determination?

    Let's consider a typical Zone III printing test. The idea is to expose the paper where Fb+b is paper black, then see where Zone III falls. In the test, the exposure range between the Zone I exposure and the Zone III exposure is two stops. According to Curve A example, Zone III under a zero flare condition will have a density of 0.43. There is virtually no flare when shooting single toned subjects. In the field under flare conditions, Zone III falls only one stop to the right of the Zone I exposure and according to Curve B will have a density of 0.29. What is the purpose of a test that doesn't reflect use?

    Here's a funny little saving grace. Since the Zone System doesn't factor in flare with it's speed testing, it tends to produce film speeds 1/2 to one stop below the ISO speed rating. This will shift all the exposures to the right on the curve effectively bringing the Zone III density up to or above the density used in the test. There will almost always be accent black and the change in the lower shadow placement from the lower EI setting will not be noticed.

    And why do you suppose example A represents the most prevalent approach to curve interpretation in the photographic community when the results are less than representative?

    I believe a large part of the problem is caused by the tendency to isolate the film curve away from the camera image/flare curve and the paper curve. Most of the time, we aren't see the whole picture. Add the camera image quadrant and now it's possible to see how the original image changes inside the camera and how the exposure values shift as they move from the subject through the camera to the film. Add the paper curve, and it's now possible to compare how the original tonal values are represented in the final product.

    I'm going to work on some examples to illustrate some of this and will hopefully have something to show tomorrow.
     
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  19. Bill Burk

    Bill Burk Subscriber

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    OK it's getting late, but with all the clues, I have to take one more stab... The one on the left is a subject with a majority in shadow, "low-key". The one on the right, exhibiting more flare, is a "high-key" scene with more light subject matter. Both subjects were selected to have all zones, just not equally represented.

    ... not the right answer...
     
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  20. joh

    joh Subscriber

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    I would say A is the right one for a N development,
    N has a difference from 7 Zones ( 7 f-stops) between Zone VIII and Zone I.
    One f-stop has 0,30 log.D ....0,30 * 7 = 2,10.
    The B graph has a difference from 1,78 log.H this would mean 6 f-stops
    0,30 log.D * 6 = 1,8.
    In my opinion it show's a N+1 development, not implicitly from the result
    but from the exposure.
     
  21. Stephen Benskin

    Stephen Benskin Member

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    You'd think that something that has been around for over 70 years would have been better defined by now. In sensitometry, 0.30 is always a stop. With Zones, I see it as a change from one Zone to the next with the original subject is one stop. There has to be a unit of measurement or else it's just gibberish. With the print, I've always thought there was too much of a coincidence between the 10 steps of the Zone System and the 10 steps of Munsell's scale. As the Munsell scale is psychophysically based, the spacing between the steps are visually equal, but not equal in reflection density. However, as the average subject luminance range is 2.2 logs and the RD range for glossy paper is around 2.2, there can be (excluding specular reflections) a one to one tonal relationship with the original subject. That is except then the print would appear dark to the view under normal viewing conditions.
     
  22. Stephen Benskin

    Stephen Benskin Member

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    As to the difference in spacing of Zones along in the two examples. Everyone should be familiar with the exponential scale of exposure:

    For a seven stop scene:
    1, 2, 4, 8, 16, 32, 64, 128 for a ratio of 1:128

    Add one stop (unit) of flare and it becomes:

    2, 3, 5, 9, 17, 33, 65, 129 for a ratio of 1:64 (six stops)

    Even though the original scene is 7 stops, you are only dealing with 6 on the film curve. What are the implications of this?

    Processing normal for a seven stop scene is really processing for a 6 stop scene. Without the presence of flare, development would have to be one stop less for normal.

    The log-H range on the film curve for a seven stop scene would be 1.80 for a one stop flare factor and not 2.10. That means, the place where you determine the density range of the negative would be one stop (0.30) to the left. You can see this in the two examples. While not perfect since the flare factor in the examples is slightly higher than a stop, the density range for Zone I to Zone VIII in Curve B (flare example) is the same as the density range for Zone I to Zone VII in Curve A (no flare example).

    The two examples only differ in the interpretation of the information. So, in a shooting situation, there would be no difference in the negatives as they will be subject to the exact same conditions. The question becomes, which one reflects the way it works in the real world and which one is using the same set of conditions and coming out with the wrong interpretation / answer?

    The two curves are an example of the importance of correct interpretation of the data.
     
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  23. markbarendt

    markbarendt Subscriber

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    Agreed.

    Not agreed. Well not agreed that there needs to be a global standard.

    The zone system is an artistic ruler.

    Zones were specifically designed to translate various and sundry personally defined (artistically chosen) SBRs into a single chosen target paper's range.

    We each define how much of a given scene is important. Whatever that SBR is gets hacked up into the zones. The zones may be 1-stop or 0.7 stops wide or 1.2 stops or whatever.
     
  24. Stephen Benskin

    Stephen Benskin Member

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    Sounds more like a religion to me. Sorry that was flip. I was being flip with Kirk too. Basically, if there's no precision in a language, how can ideas be properly communicated?

    According to Zone System testing, Zone I is four stops down from Zone V and Zone VIII is three stops up from Zone V. Sounds to me like the the Zones in the 7 stop range between Zone I and Zone VIII are divided into one stop steps.

    And who ever said sensitometry isn't creative? The Zone System is basically simple sensitometry (which includes Tone Reproduction Theory). Perhaps it's more accurate to say the Zone System uses Tone Reproduction Theory.
     
  25. DREW WILEY

    DREW WILEY Member

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    OK, I see the game you are playing. The graphs show up poorly on my screen. But my general position is
    the same. The Zone System is only what you want it to be, unless you think Minor White or Ansel A. were Moses and wrote the rules on stone tablets. You can think of the dynamic range of films subsisting
    between Zones II and VIII or III and VII, or 0 to XII. I just depends on the variables. If you "standardize"
    on a film with a modest straight line section, then adapt you model to one with a long straight line, you
    either change your vocabulary or break your own rules. And real world exposures rarely correspond to
    what happens with a step tablet.
     
  26. Stephen Benskin

    Stephen Benskin Member

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    And man never walked on the moon. You don't have to come up a conspiracy story. Just read some material on Tone Reproduction Theory. The specific purpose of Tone Reproduction Theory is to model how the photographic process works. Claiming that science doesn't reflect the real world is just an absurd argument.

    If you are going to accuse someone of something, bring up specifics, make an argument, so that we can discuss the issue. You're not claiming that flare doesn't exist, are you?
     
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