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  1. #21
    Stephen Benskin's Avatar
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    I wrote an article that addressed the seemingly incompatibility between the ZS definition for paper LER and Tone Reproductions. It was supposed to be a companion piece to the flare and film contrast article. PT felt one paper on the subject of flare was enough tech for them. It wasn't published. Now, I can't even find it on my computer. I hope it's archived some where.

    Basically, factoring in flare seems to solve the discrepancy. I had graphs and everything. I've actually found flare to be the cause of most of the misunderstandings and / or confusion with tone reproduction.

  2. #22
    Stephen Benskin's Avatar
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    Allen,

    I'd like to make just a few comments. Donald isn't all that off about is conclusion with the neg DR suggested by Adams. No it wasn't arbitrary, but it might as well be based on what Adams wrote in The Print. He rejected using "numbers" with printing. I found this strange. Without having a at least the relationship between the negative and the print, the negative density values will exist in a vacuum where they might as well be arbitrary.

    Based on many misconceptions and inaccuracies in Adams writings I have to conclude he really didn't have a full grasp of sensitometry or more precisely tone reproduction. What I do find interesting is while his conclusions or interpretations of the conditions are wrong, the results tend to work. Consider the aim 1.25 density range as Normal. When you plug it into the gradient formula along with the 7 stop zones, you get 1.25/2.1 = 0.595 which is damn close to Kodak's normal of 0.58. Now, it you consider that the statistically average scene is 7 1/3 stops, the gradient becomes 0.57. So, even though his idea of a LER 1.25 doesn't correspond to tone reproductions 1.05, it still works. Why? 2.1 or 2.2 are the scene averages for a normal scene, but tone reproduction factors in flare which reduces the SLR from 2.2 down to approx. 1.86 or with the revised flare value, down to 1.80. So 1.05 / 2.2 -.40 equals 1.05 / 1.80 = 0.58. Both get you to the same point, but only one actually explains it correctly.

    The idea that Adams was correct at the time and it's the papers that have changed misses the fact that tone reproduction existed at that time. The basic aim values of subject luminance range, flare, and paper LER have remained rather constant. Sandy's interesting exchange about old AZO papers in another post, I think, supports the idea of the consistency of paper contrast over the years.

  3. #23

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    Quote Originally Posted by Stephen Benskin
    Now, I can't even find it on my computer. I hope it's archived some where.
    Steve - did you send me a copy of that one? If so, I'm sure I've got it in my email. Do you remember the title?

    Kirk

  4. #24
    Stephen Benskin's Avatar
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    Hey Kirk,

    It was something like "Print Contrast: Flare, Zone System, and Sensitometry."

    Steve

  5. #25

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    I'll try to look for it tonight or tomorrow.

    Later

    Kirk

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