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  1. #11
    gainer's Avatar
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    We have two different considerations. I do not remember from what I have seen of BTZS that the problem of relating densitometer readings to paper response was addressed for pyrogallol or catechol stained negatives printed on VC paper, where the ratio, so to speak, of blue to yellow has an effect on the contrast of the paper response. I have not found, after considerable effort, a way to go from densitometer readings of stained negatives to choosing the proper VC filtration to fit the scale of the negative. I have designed and built my own projection densitometer with two adjustment dials, one for slope and another independent one for level. I should be able to set those two scales to match any filter from a set or any dial setting on a color head, but there is still the unknown of the ratio of stain image to silver image and how that ratio interrelate the color sensitivity of the densitometer with the response of the paper. Sooner or later you will have to make up some tables, and there will be at least one for each developer, each film, each filter or filter setting of the enlarger, and all this to take the place of some simple test strips, which you will either have to do for corroboration or risk a large sheet of printing paper on the basis of a densitometer reading.
    Gadget Gainer

  2. #12
    Jim Fitzgerald's Avatar
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    Pat, I see that my curiosity could get very time consuming with testing. Maybe I'm better off just wondering about this stuff and be more concerned about exposing negative and just printing them! Thanks for your help.

    jim

  3. #13
    gainer's Avatar
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    P.S.
    IIRC, the Zone system was a musician's (and a very fine one's) way of comparing the visual tone values in a scene to an octave from no sound to inaudibly high sound. Most fine musician's I have known have some innate mathematical sense. Some have been professional mathematicians as well, and others in other technical fields. Some of them would say I was one of them. The complexity of Zones in fractions other than half tones is, I think, the product of other than musical minds.
    Gadget Gainer

  4. #14
    Jim Fitzgerald's Avatar
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    Quote Originally Posted by gainer View Post
    P.S.
    IIRC, the Zone system was a musician's (and a very fine one's) way of comparing the visual tone values in a scene to an octave from no sound to inaudibly high sound. Most fine musician's I have known have some innate mathematical sense. Some have been professional mathematicians as well, and others in other technical fields. Some of them would say I was one of them. The complexity of Zones in fractions other than half tones is, I think, the product of other than musical minds.
    Pat, this is a good analogy. I can relate. Although I'm challenged with math my three sons are not. They are all three very fine pianists. They have performed with symphony orchestras as soloists. My oldest and most gifted was told by a conductor during a rehearsal for a performance of Beethoven's Emperor Piano Concerto how precise his timing was. It was just part of who he is. It is a very demanding piece for a 17 year old and thankfully I have the CD of this astounding performance. I do believe math and music go hand in hand. Must be why I turned to photography! Could not get the music thing going.

    Jim

  5. #15
    Jim Fitzgerald's Avatar
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    Quote Originally Posted by Marc . View Post
    Jim,

    Here is also a link to a Kodak workbook on sensitometry (this is the name of the thing...)
    http://www.kodak.com/US/plugins/acro...y_workbook.pdf

    Phil Davis' book covers the same subject, explaining each concept and suggesting exercises.

    The effort to read these books is well worth it !

    Best,

    Marc
    Marc, good read. I have it saved. Thanks.

    Jim

  6. #16
    Jim Fitzgerald's Avatar
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    Quote Originally Posted by Curt View Post
    I have a Macbeth densitometer and a Stouffer calibrated scale so I can make sure the densitometer is reading correctly. In the back of the book "The New Zone System Manual" White - Zakia - Lorenz, is an excellent explanation relating the paper to the film and both to the Zone System. In the Appendix, I, Calibration with Densitometer and Graphs explains step by step how to take measurements and plot the curves, very nice to know for contraction and expansion. Flair, reciprocity and other topics that come into play are also covered. It's a book well worth having.

    Stouffer site: http://www.stouffer.net/TransPage.htm

    Curt
    Curt, the book seems to be what I'm looking for . Thanks.

    Jim

  7. #17

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    hey Jim
    why not just make a print and visually appraise the result

    Ray

  8. #18
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    Quote Originally Posted by gainer View Post
    P.S.
    IIRC, the Zone system was a musician's (and a very fine one's) way of comparing the visual tone values in a scene to an octave from no sound to inaudibly high sound. Most fine musician's I have known have some innate mathematical sense. Some have been professional mathematicians as well, and others in other technical fields. Some of them would say I was one of them. The complexity of Zones in fractions other than half tones is, I think, the product of other than musical minds.
    There are two important difference here that must not be forgotten.

    1. Density is always in a visible range, not from invisible (0) to infinitely high. This is not within the reach of todays films (or digital) products. The lowest finite density is about 0.1 and the highest film value is about 3.0, both well within the visible capability of a single scene.

    2. Half tones or less than half tones are not used in film. The 21 step scale is measured in stops and half stops which are real speeds on the camera. These steps attain in any image and the only variable is the shifting of the ISO range of a given film within which something is photographed. Thinking in less than stop or half stop changes is not common, but thinking in a continuous density scale is quite within the range of common practice in analog photography, if not in digital.

    PE

  9. #19
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    I should amend the above regarding tones and half tones to exclude the dot processes of halftone images which are not within the scope of this. It is an entirely different matter than should not be misconstrued to be included in either my comments or Patricks.

    PE

  10. #20
    Jim Fitzgerald's Avatar
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    Ron, I am truly amazed by the depth of knowledge that you and Patrick and others on this forum have and are willing to share. You give me a lot to think about and ponder. Thank you so much for that.

    Jim

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