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  1. #31
    Ian Grant's Avatar
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    Back to the original post, I thought long and hard about this, late 19th C films and paper combinations were able to reproduce far longer tonal scales, but why.

    I've just been asked to write about home emulsion manufacture and have been going through my old research notes earlier. As I lay in bed I suddenly realised what we've all been missing: They are all contact printed on silver gelatin POP, or possibly silver chloride gelatin emulsion (pre AZO) they arent enlargements.

    So hence the long deep tonal ranges.

    We all missed the obvious :-)

    Ian

  2. #32

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    Isn't long tonal range just the same thing as low contrast? I get a nice long range on grade 1 paper. I don't think that these old papers had any better reflection density range.

  3. #33

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    Quote Originally Posted by ChuckP
    Isn't long tonal range just the same thing as low contrast? I get a nice long range on grade 1 paper. I don't think that these old papers had any better reflection density range.

    No, it isn't the same. The gradient of the straight line is not the same. So one can have a long scale material with a flatter gradient which is evidenced as lower local contrast. For example, when comparing grade 0 or grade 1 of one paper to another longer scaled grade two material, one may very well find that while the length of scale may be the same the gradient can be markedly different.

    In the example above, while the grade 0 or grade 1 may hold both ends of the negative density range, it will lack life because local contrast and reflection densities will be markedly different.

  4. #34
    Ian Grant's Avatar
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    As my post about POP or Silver Chloride paper was made as I jumped out of bed and stumbled to the computer 3 floors below perhaps I should elaborate.

    Actually Jorge suggested Albumen prints, I suggested POP. Neither would produce the deep greys and rich blacks shown in the images in question.

    I said perhaps Silver Chloride/Gelatin prints and thinking about it during the day that is what they are.

    So whats the differance between POP and a Silver Chloride paper, not a lot the differance is the Silver Chloride emulsion is washed while still in a jelly form to remove the by-products of combining Silver Nitrate with a gelatin solution containing Sodium Chloride. This removes the excess Sodium Chloride and the Sodium Nitrate, leaving only the newly formed silver chloride in the emulsion.

    The result is a slow contact printing paper (similar to Azo) that needs development - amplfication - to generate a print. That development generates the long grey scale and amazing depth in the blacks.

    In a PM Jorge mentions the inconsistence of paper base colour, it may be due to aging or possibly papers sourced from different manufactures, or deliberatly coated on different paper bases we'll never know.

    Ian

  5. #35

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    Quote Originally Posted by Donald Miller
    No, it isn't the same. The gradient of the straight line is not the same. So one can have a long scale material with a flatter gradient which is evidenced as lower local contrast. For example, when comparing grade 0 or grade 1 of one paper to another longer scaled grade two material, one may very well find that while the length of scale may be the same the gradient can be markedly different.

    In the example above, while the grade 0 or grade 1 may hold both ends of the negative density range, it will lack life because local contrast and reflection densities will be markedly different.

    Seems like you will need to have low contrast someplace on the curve. If the midtones are steep then the shadows or highlights will need to be lower. I thought that a steeper gradient in a straight line curve would result in the need for a negative with less density range to fit the paper scale. If the paper scales are the same and the negative densities to fit are the same, how can one paper curve be steeper throughout the entire range and still fit the negative.

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