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Thread: Zone Placement

  1. #121
    Stephen Benskin's Avatar
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    Quote Originally Posted by Bill Burk View Post
    Looks like that separation in the higher tones exists in the negative, could be accommodated by developing less, to fit the paper better or altering paper grade.
    The negative density range really didn't change, the higher exposure took the shadows off the toe which increased their separation. I think the highlight gradient took a small hit was because there looks to be an ever slight downward shift in the upper portion of the film curve.

    The guideline chart appears to support that assumption. Although because of the really small sampling area used to determine the local gradient, small reading and plotting anomalies in the curve can have a rather large influence on the value. Curve smoothing might be an option.
    Attached Thumbnails Attached Thumbnails Quad 2 guideline gradient comparison.jpg  
    Last edited by Stephen Benskin; 09-14-2011 at 06:56 AM. Click to view previous post history.

  2. #122
    Bill Burk's Avatar
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    This thought occurred to me...

    As I strive to figure out the lower EI that most Zone System users settle on vs box speed...

    Loyd Jones' tests were the first excellent print, right? He sent the films off to the lab to make the best print they could of each negative. The first excellent print might have been on Grade 4 paper for all I know, the guys in the lab were doing their best.

    Zone System tests aim to fit onto Grade 2 paper. So this could be another factor why the EI is lower for Zone System users.

  3. #123
    Stephen Benskin's Avatar
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    Quote Originally Posted by Bill Burk View Post
    This thought occurred to me...

    As I strive to figure out the lower EI that most Zone System users settle on vs box speed...

    Loyd Jones' tests were the first excellent print, right? He sent the films off to the lab to make the best print they could of each negative. The first excellent print might have been on Grade 4 paper for all I know, the guys in the lab were doing their best.

    Zone System tests aim to fit onto Grade 2 paper. So this could be another factor why the EI is lower for Zone System users.
    It's been awhile since I've done a thorough reading of the paper so... What they did was make a bunch of negatives from master transparencies varying the exposure and processing. A bunch of prints were made from each of the negatives. The prints were judged for quality and then they went back to determine the sensitometric conditions that produced the best quality images. Finally, they had to come up with a way to determine a film speed that would be in agreement with the results they got in the psychophysical testing. Technically, the best method for speed determination is with psychophysical testing like the first excellent print. It's just not practical to do. What is regarded as the best method to determine film speed would be the mathematical approach that will give results as close as possible to the psychophysical test with the greatest number of different types of film. Attached. Notice the fixed density 0.10 method has the worst results?

    There's a concept that I've been thinking about having to do with considering the guidelines used for the judges. They instructed the people judging the prints to base their standards of quality on prints that they thought best produced an impression of what they believed the original scene would look like if they were there. In other words, prints that most closely looked like reality.

    What if the intention of the photographer isn't about making the finished print "look" like the original scene? Wouldn't that mean the judging conditions of the testing that determined film speed no longer applies? So the film speed value is, in a way, no longer accurate? Of course, there needs to be some kind of standard in order to have a base to work from and be able to compare apples to apples, but something to consider.

    The subjective element of photography is the saving grace of so many "systems." If the intent was to reproduce something exactly, there wouldn't be a debate.

    And no, the reason the Zone System speeds are different from the ISO speeds is because the testing methods have different parameters and assumptions. ISO the shadow is 4 1/3 stops below the metered exposure point, but the speed point is 3 1/3 stops because they factor in flare. Zone System has the shadow 4 stops below. EI has to be adjusted by 2/3 stop to bring it up to the 0.10 Fb+f speed point. Also attached is a example from an article I wrote for PHOTO Techniques. For the record, speed point isn't necessarily the point were a specific exposure is supposed to fall (eg shadow exposure), but just a knowable place to calculate film speed.

    There are reasons why people haven't caught this, and quality isn't one of them. A little extra exposure doesn't degrade quality and can be considered a good idea, even if you're not aware of it. But I think it's important to keep in mind there's a difference between film speed and preferred exposure.
    Attached Thumbnails Attached Thumbnails spread function for Delta X.jpg   Zone System testing and Exposure placement.jpg  
    Last edited by Stephen Benskin; 09-14-2011 at 10:27 PM. Click to view previous post history.

  4. #124

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    Quote Originally Posted by Bill Burk View Post
    Zone System tests aim to fit onto Grade 2 paper. So this could be another factor why the EI is lower for Zone System users.
    My feeling has always been that this occurs because a reflected light meter does not generally produce 18 percent gray unless you open up 1/2 to 2/3 stop from the reading of a gray card. It produces 12 percent gray (or slightly different, depending on the K values used by the light meter maker). Interesting how working EIs obtained via Zone System testing are quite often 1/2 to 2/3 EI slower than box speed. So, in it's own little bubble, the Zone System works great. But it is hard to compare it directly to other systems of exposure and development because it uses different criteria for calibration.

    Once I stopped using the Zone System primarily for my "static" pictures, and started calibrating to gray scales and using an incident meter, I started noticing that box speed and manufacturer's recommended development were almost always very close to being spot on.
    2F/2F

    "Truth and love are my law and worship. Form and conscience are my manifestation and guide. Nature and peace are my shelter and companions. Order is my attitude. Beauty and perfection are my attack."

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  5. #125
    Stephen Benskin's Avatar
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    Quote Originally Posted by 2F/2F View Post
    My feeling has always been that this occurs because a reflected light meter does not generally produce 18 percent gray unless you open up 1/2 to 2/3 stop from the reading of a gray card. It produces 12 percent gray (or slightly different, depending on the K values used by the light meter maker). Interesting how working EIs obtained via Zone System testing are quite often 1/2 to 2/3 EI slower than box speed.
    This might be true if speed was determined at the metered exposure point. Making the assumption that meters "see" at different values would explain the different interpretations of the results. And rating the EI at 1/2 stop less than the ISO would bring Zone V up to equal 18% reflectance but only if you are using the modern values for K and C. But speed point isn't determined at the metered exposure. (K works differently than how most people think. See here for the thread with a very detailed explanation.)

    It also doesn't explain why the general refrain is "1/2 box speed" (one stop vs the 1/2 stop 18%/12% difference), or that there isn't any evidence the mantra was heard before 1960. ASA film speeds where approximately one stop slower pior to 1960. The attachment is from a Kodak data book from the 1950s. The Zone System's fundamental testing method was the same then as today. From all indications the ZS and ASA speeds tended to conform. They wouldn't if it was about a light meter calibration discrepancy.

    The relationship between the metered exposure point to b&w speed point can be defined as the Hg/Hm where Hg is the exposure at the meter exposure point and Hm is the exposure where the film density equals 0.10 Fb+f. For a given film speed Hg = 8/ISO and Hm = 0.8/ISO. The ratio, k1, can also be found using the two constants 8/0.8 = 10, or 1.0 logs, or 3 1/3 stops.
    Attached Thumbnails Attached Thumbnails Kodak Data book - old film speeds.jpg  
    Last edited by Stephen Benskin; 09-15-2011 at 04:51 AM. Click to view previous post history.

  6. #126

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    Quote Originally Posted by Stephen Benskin View Post
    This might be true if speed was determined at the metered exposure point. Assuming meters "see" at different values would explain the different interpretations of the results. (Sorry, I dislike using percentages because meters read luminances not percentages.) And yes, rating the EI at 1/2 stop less than the ISO would bring Zone V up to equal 18% reflectance but only if you are using the modern values for K and C. But speed point isn't determined at the metered calibration point.

    It also doesn't explain why the general refrain is "1/2 box speed" (one stop vs the 1/2 stop 18%/12% difference), or that there isn't any evidence the mantra was heard before 1960. ASA film speeds where approximately one stop slower pior to 1960. The attachment is from a Kodak data book from the 1950s. The Zone System's fundamental testing method was the same then as today. From all indications the ZS and ASA speeds tended to conform. They wouldn't if it was about a light meter calibration discrepancy.

    The relationship between the metered exposure point to b&w speed point can be defined as the Hg/Hm where Hg is the exposure at the meter exposure point and Hm is the exposure where the film density equals 0.10 Fb+f. For a given film speed Hg = 8/ISO and Hm = 0.8/ISO. The ratio, k1, can also be found using the two constants 8/0.8 = 10, or 1.0 logs, or 3 1/3 stops.
    Stephen,

    It sounds like you maybe misunderstood what I wrote. I am not saying the reason for lower Eis is differences in light meter calibration or K values. I am saying it is the different (flawed?) methodology of how the Zone System uses a gray card.

    Technical jargon aside, in the Zone System, the gray card is used as the tool for finding an EI. A reading is taken, and this reading is then stopped down from to what Ansel Adams thought "should" be the threshold of density. However, the way I see it, he was wrong; where he chose to stop down to really should not have been the threshold of density; it should have been 1/2 stop below the threshold of density. In short, Adams' whole darned thing was off by a half stop from the get go; he was confused as to how to use a gray card to determine a correct exposure (forgot the bit about opening up from the reading). It works in and of itself, but it sure would be nice if Zone System EIs were closer to box speed. The difference is building the adjustment into the EI, as Adams did, or adding it each time you take a shot, as I prefer to do, so I can use incident and spot meters together to find my exposure and development for a picture.

    Also, the common refrain of "rate your film at half box speed" is, IMHO, sloppy, and wrong, as are most rules of thumb when adhered to without thought. I never do that unless testing has indicated that I should...and it only has on two or three occasions, with older film. As mentioned above, I find box speed and manufacturer's recommended developing times to be scarily close to dead on for me when using an incident meter and a reflected gray scale for testing...and when used with reflected meters, if I add the 1/2 to 2/3 stop that I am supposed to (that it says to do right on the back of my gray card).

    In short: It makes sense to me that Zone System EIs are lower than box speed because of the methodology of the initial EI test. Ansel Adams was off by 1/2 a stop from the get go. The whole system is offset from box speed 1/2 stop automatically by this fact alone.
    Last edited by 2F/2F; 09-15-2011 at 05:05 AM. Click to view previous post history.
    2F/2F

    "Truth and love are my law and worship. Form and conscience are my manifestation and guide. Nature and peace are my shelter and companions. Order is my attitude. Beauty and perfection are my attack."

    - Rob Tyner (1944 - 1991)

  7. #127
    markbarendt's Avatar
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    Quote Originally Posted by 2F/2F View Post
    Once I stopped using the Zone System primarily for my "static" pictures, and started calibrating to gray scales and using an incident meter, I started noticing that box speed and manufacturer's recommended development were almost always very close to being spot on.
    This has been my experience too 2F/2F.

    Over the last year I started making the transition from zoning and 1/2 box speed to the almost exclusive use of incident metering at box and it really has made a significant improvement in the quality of my exposures.

    Part of what I find interesting in Stephen's example in post 123 is that flare has little effect up near the meter calibration point. To me that screams "middle tones are better reference points".

    Another thing that I've noticed is that for any particular shot there appears to be a point where the print looks natural, surely there s a range in which it can be printed nicely, but the farther I stray from normal exposure (incident in my case) the tougher it is to make the shot look right on paper.

    It s no stretch for me to believe the psychological testing results.

    As a side note, this has pushed me more toward finding or creating better lighting or filtering or using graduated NDs, for my shots rather than trying to burn or dodge after the fact.
    Mark Barendt, Beaverton, OR

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

  8. #128
    Stephen Benskin's Avatar
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    That doesn't explain why speeds conformed before 1960, but not after. Adams was only a little off in his assumption that the shadows fell 4 stops down, as opposed to 4 1/3. Based on the way ZS tests, this should actually make ZS EIs 1/3 stop faster than the ISO speed if this was the only factor. The real question is why is the ratio between Hg and Hm 3 1/3 stops and not 4 1/3. The answer is, this is the way flare is factored into the calculation. The attached paper is on meter calibration.

    The reason why they conformed before 1960 is because the ASA standard had an extra stop safety factor which just happened to compensate for the difference in testing methodology.
    Last edited by Stephen Benskin; 09-15-2011 at 06:50 AM. Click to view previous post history.

  9. #129
    Bill Burk's Avatar
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    Quote Originally Posted by 2F/2F View Post
    However, the way I see it, he was wrong; where he chose to stop down to really should not have been the threshold of density; it should have been 1/2 stop below the threshold of density.
    Not to detract from the rest of your post...

    The gray card will read whatever it reads, even a 33% gray target (to pick a random number) when metered and stopped down 4 stops will put the same exposure on the film as a standard gray card.

    Because the gray card is the subject when you make the exposure, it doesn't matter what percent it is.

    Normal gray card usage, where the percentage matters, you take the gray card away and shoot a pictorial subject.

  10. #130

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    Quote Originally Posted by Bill Burk View Post
    Not to detract from the rest of your post...

    The gray card will read whatever it reads, even a 33% gray target (to pick a random number) when metered and stopped down 4 stops will put the same exposure on the film as a standard gray card.

    Because the gray card is the subject when you make the exposure, it doesn't matter what percent it is.

    Normal gray card usage, where the percentage matters, you take the gray card away and shoot a pictorial subject.
    You can indeed use any even-toned surface for Zone System testing. The point about 18 percent was simply to point out that most light meters are designed to produce a darker tone of gray than a "middle gray" card, so the middle-toned card is not reproduced accurately if it is exposed at zone V (i.e. if the meter reading is used directly); if you expose directly off of a gray card and print normally, you get a tone on the print that is darker than a the gray card. Expose off of anything, and you get that slightly-darker-than-a-gray-card gray. Since print value V should look like an 18 percent gray card, and should correspond with a zone V placement and normal printing, I would personally reason that 4 stops is too much to stop down to expect to land on the threshold of density, and 3-1/2 should be where you start looking for zone I. Knowing that a reflected light meter will reproduce a tone that is actually about 1/2 stop darker than middle gray, I'd expect stopping down four stops from the reading to give me a print value "1/2," not I. It isn't about the tone of the gray card, except to say that light meters do not accurately reproduce one unless the reading is adjusted a bit, so we should not expect a zone V placement to give us a gray card gray on the print. Not saying that the Zone System is wrong. It simply builds that 1/2 stop into the working EI...thus lowering speeds below box speed. That is great if all you use is the Zone System. But try combining it with other methods, and it is a bit awkward. I use incident meters, and use spots to measure luminance range, with the occasional placement of a certain subject, or simply the measurement of one to know where it will land tonally at my decided-upon incident exposure.
    Last edited by 2F/2F; 09-15-2011 at 11:13 AM. Click to view previous post history.
    2F/2F

    "Truth and love are my law and worship. Form and conscience are my manifestation and guide. Nature and peace are my shelter and companions. Order is my attitude. Beauty and perfection are my attack."

    - Rob Tyner (1944 - 1991)



 

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