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  1. #11

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    The film base used for 135 film usually contains a dye which is part of the plastic and not soluble in water or any processing solutions. Other formats usually do not have a similar film base. In any measurement of base fog the presence of this dye must be taken into account since the density it contributes is not fog. For many years the film base used for Kodak Plus-X 135 had a very dark blue color. No amount of washing could remove this dye.
    A rock pile ceases to be a rock pile the moment a single man contemplates it, bearing within him the image of a cathedral.

    ~Antoine de Saint-Exupery

  2. #12
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    Quote Originally Posted by Gerald C Koch View Post
    The film base used for 135 film usually contains a dye which is part of the plastic and not soluble in water or any processing solutions. Other formats usually do not have a similar film base. In any measurement of base fog the presence of this dye must be taken into account since the density it contributes is not fog. For many years the film base used for Kodak Plus-X 135 had a very dark blue color. No amount of washing could remove this dye.
    I was surprised no-one mentioned this before. It's quite noticeable with some films and is why Foma's reversal film is on a clearer base thantheir other films, and theur 120 films were on a very blue base this makes no difference to printing.

    Ian

  3. #13
    AgX
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    For clarification as there arose some confusion:

    There are two kinds of AH-dyes:

    -) those in a special AH-layer (typically volatile whilst processing, though sometimes not dyes in the proper sense)

    -) those embedded in the base (fixed, but not used in all types of film)


    When speaking of AH-dyes here at Apug typically the former are referred to, Prof_Pixel obviously referred to the latter.

  4. #14

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    Quote Originally Posted by bascom49 View Post
    I developed a roll of HP5, Tmax 100 and Delta 100 in Xtol, base + fog for all 0.08 to 0.1.

    Does 35mm have a higher base + fog than 120 ?
    I should have clarified that these rolls giving me a lower base + fog densitometer reading were 120 medium format.

    While not to laboratory standards I do think that my comparative testing between the two formats is accurate.

    All films were washed for two minutes after fixing in running water, followed by two minutes in Kodak Hypo and then washed for ten minutes in running water.

    I'm fairly sure that my washing procedure is adequate. If anyone else has an opinion please share.
    The film base color is grey, not purple but very clear, not fogged.

    I found a set of negatives that I had processed and printed from 135 Tmax 100 last year of a water fall. The film base is lower than Panf, HP5 and FP4 but markedly higher than Tmax 100 in medium format.

  5. #15
    AgX
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    One could see it as a classic concept to give types 120/222 just an AH-layer on a colourless base and type 135 an AH-layer on a dyed base (plus even different base thiknesses).

    (As other concepts in converting one could challenge this.)


    If one needs a figure for base+fog, one should meter a sample from the very lot of film and processing in question.

  6. #16

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    I asked Simon at Ilford and he was gracious enough to send me a reply.
    I'll certainly continue my support of Ilford and Ilford products.
    I encourage everyone else to as well.


    Dear Charles,

    The base density on 35mm ( miniature ) film is higher than on 120 ( different substrate ), dyes in the emulsion and the film has a buffer to prevent light piping.

    Thank you for using and valuing ILFORD Photo products :

    Simon. ILFORD Photo / HARMAN technology Limited :

  7. #17

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    Quote Originally Posted by AgX View Post
    For clarification as there arose some confusion:

    There are two kinds of AH-dyes:

    -) those in a special AH-layer (typically volatile whilst processing, though sometimes not dyes in the proper sense)

    -) those embedded in the base (fixed, but not used in all types of film)


    When speaking of AH-dyes here at Apug typically the former are referred to, Prof_Pixel obviously referred to the latter.
    Yes. That's why I said "What you are seeing is the antihalation dye in the 35mm base." and NOT "on the 35mm base"

  8. #18

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    Quote Originally Posted by Prof_Pixel View Post
    Yes. That's why I said "What you are seeing is the antihalation dye in the 35mm base." and NOT "on the 35mm base"
    I took your info as fact and I appreciate your comment. I had already pm'ed Simon and just thought to share his response.

  9. #19

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    Quote Originally Posted by Ian Grant View Post
    I was surprised no-one mentioned this before. It's quite noticeable with some films and is why Foma's reversal film is on a clearer base thantheir other films, and theur 120 films were on a very blue base this makes no difference to printing.

    Ian
    I think why no one mentioned this initially (and I include myself) is that we assumed that the OP and others had made this very important correction.

    Jerry
    A rock pile ceases to be a rock pile the moment a single man contemplates it, bearing within him the image of a cathedral.

    ~Antoine de Saint-Exupery

  10. #20

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    Does 35mm have higher base + fog than 120 ?

    I have a Kodak publication which gives typical b+f densities for their films;
    T-max100 in 35=0.24 in120=0.11
    T-max400 in 35=0.27 in 120=0.11
    Sheet film for both speeds is 0.08
    The book is called Advanced Black-and-White Photography from the Kodak Workshop Series

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