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  1. #51

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    Quote Originally Posted by Photo Engineer View Post
    Keep that Sands dye alive guys.

    Here is the big secret! It is the red sensitizer for KODACHROME! It is one of the few dyes that can survive development and still be active. So, someday, if there is a researcher who wants to recreate Kodachrome, this is the dye to use.

    PE
    H

    Yeh, what was it,27 layers? I am glad that I have ZERO interest in color film, homemade or commercial. Gimme color separation any day. I have been that way ever since I first read about how Technicolor worked. STILL the best process ever.

  2. #52
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    Not that many, and it sure was sharp!

    PE

  3. #53

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    People will be harvesting the Kodak patents for a thousand years. I have always thought the Kodachrome structure was a robust design, saving a lot of work which would be required for built-in couplers and the manufacture of chemicals which would be stable in the field. Its principal innovation was to solve the registration problem which was an issue with Technicolor DT. Kodachrome will still be with us in one way or another. Now that PE has revealed the red light sensitizing dye, Kodachrome is yet another step closer to becoming an amateur-built process.

    I share the admiration for what was traditionally called the Technicolor 3-strip process. The camera was essentially a "one-shot" design and the separation negs which it produced tended to have higher contrast high-light to low-light than the separations produced in chromogenic films. Technicolor DT prints therefore often had a fully saturated portion of the frame. This can be very satisfying to color lovers as well as producing a very deep gamma black--darker than most chromogenic blacks. Also the process allowed considerable latitude to produce the final "look" of the film. Technicians could work in daylight balancing contrast and gamma. More importantly they could use a wide variety of dyes and dye mixtures to produce the hues, all of which could be found on the commercial market. Chromogenic films could only use dyes which were produced by coupling-development. This limited the dyes available so that hues and saturation could suffer. But Technicolor could mix up a separate soup of dyes for each new film it produced. In addition, two or more dyes could form the complementary colors. The process made the human face look beautiful and allowed for very pure tones in the low-lights. This made for rich sunsets and clear views of dark interiors. I doubt if "The Godfather" would have looked as good if it had not been printed in Technicolor DT.

    Finally there is the stability of the dyes--for years the best in the industry. About six months ago I saw a Technicolor DT print of a short of the World's Fair in Flushing Meadows which was printed up in 1964. The film looked like it had been produced yesterday. DT prints are some of the most satisfying images in analogue photography.

  4. #54

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    I have 3 of those one-shot cameras. In various stages of restoration. Man! if anyone thinks that view cameras are "complicated", get a one-shot 5x7. Alignment of focal planes is a bitch. But God made black and white film. The existence of color film was one of mankind's mistakes. Lie bird feeders. Eeck.

  5. #55

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    Good lord, I have a whole gallery of color photographs of bird feeders! Now I realize that I have made a ghastly mistake! They should have been photographed in black and white.

  6. #56

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    That's OK falotico. Many people have regrets about their lives. Wasting ones life on color film is a hard fact to accept. Kind of like realizing that you rejected your Soul Mate because you were too shy.

  7. #57

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    Quote Originally Posted by Photo Engineer View Post
    Bill;

    In practice, you must determine the best level of dye by trial and error. I always do a concentration series.

    And, the amount varies from emulsion to emulsion and of course if you want J aggregation it takes 2x the amount, however if aggregation is going to take place it will and may only cover 1/2 of the emulsion. Therefore it is best in this case to optimize for the aggregate to form rather than some sort of mix.

    PE
    PE,
    Since SD3057 without J aggregation is a green sensitive dye, Would it not be possible to create an RGB sensitive emulsion by aggregation of only some of the Ag halide-dye?.
    I have never attempted to produce panchromatic emulsion with only one dye. But care with both concentration and mixing of the dye might make this possible.
    Or, is my neighbor smoking something that is drifting over here? THAT is a real possibility. It ain't my fault. This is San Bernardino. Drugs are all over and used by people you would never suspect.
    Even Retired Kodak engineers,PE.

  8. #58
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    Bill, it is indeed possible to make a pan sensitive emulsion with this dye, but you must remember that it re-equillibrates in the melted emulsion and in the coating as it keeps (although this is very slow). So, what you get is a changing emulsion.

    Remember that J aggregation depends on Iodide content and thus it is possible to get red and green by using an Ag/Br/I and Ag/Br mix provided that you can get them up to comparable speeds and curve shapes kinda match.

    PE

  9. #59

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    Thanks PE,
    This shall be my next emulsion. Hopefully not the next and the next and the next.--------------------------------------------------------------------
    Bill

  10. #60

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    PE,
    Some years back, you indicated that for a panchro emulsion, it is best to mix a each dye into a separate section of emulsion, then mix the 3 portions. Then, just a few months ago, you said that a blue sensitive portion, with no dye was not required. I have found the latter to be true I think that my next emulsion will contain only SDA3057. Half will contain only Br,or Br plus a small amount of I. The other half will contain Br plus a greater dose I.
    Comments?
    It has occurred to me that, because my work involves in camera color separation, I do not need a panchro emulsion. I could just use 3 differently sensitized emulsions.



 

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