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  1. #1

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    Speed of Bergger BPF18

    I wanna try this in an 8X10 and read somewhere to expose it at 25 or 50, does this jive? But I lack development times and dilutions, any ideas for DK72 or Pyro Cat? Thanks.

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  2. #2
    gma
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    If the 18 refers to DIN 18 film speed then that would be equal to ASA 50. If you are contact printing 8x10 you might want to increase exposure for a denser negative and use EI 25 as you suggest. I'm sure others have plenty of experience with the Pyro developer, but isn't DK72 the same as Dektol?

  3. #3

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    DK72 is an older version of Dektol (I think) and is normally what I use for Silver Gelatin. I've seen it called Grandpas Dektol and I'm not sure what the difference is if any between the two.

    Could you please explain DIN 18? Its a new term for me.

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    Ole
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    Back when everyone was different, Germany and most of Europe used DIN (Deutsche Industrie-Norm) for everything, including film speed. USA used their own standards, calles ASA (American Standards Association?). DIN doubles the speed for every 3, so a 21°DIN is half the speed (one stop slower) of a 24°DIN film. The corresponding ASA speeds would be 100 ASA and 200 ASA, so one stop faster has the double number.

    Some years ago this got internationalised to ISO, and the 21°DIN from the example above got marked as ISO 100/21°. At the same time the definition of film speed was redefined slightly, since DIN and ASA weren't quite measured the same way.

    So Bergger BPF18 is probably a 18°DIN film, or approximately ISO 64/18°.

    I still have no suggestions for development, although it wouldn't surprise me at all if the Bergger film is very similar to EFKE PL50. Or R50. Which used to be called R17, and before that was ADOX R17...
    -- Ole Tjugen, Luddite Elitist
    Norway

  5. #5

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    That answers a couple other questions I've had floating around in my head as well. Thanks.

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  6. #6
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    Not only that ... but the "ASA" (American Standards Association) doesn't exist any more - Their standards activities were taken over by "ANSI" (The American National Standards Institute); and later everything morphed into "ISO" - Internationale ... something or other.
    Carpe erratum!!

    Ed Sukach, FFP.

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    gma
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    DIN 18 is ASA 50. Three numbers higher 21 is ASA 100. DIN 24 is ASA 200, etc.

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    Quote Originally Posted by gma
    If the 18 refers to DIN 18 film speed then that would be equal to ASA 50. If you are contact printing 8x10 you might want to increase exposure for a denser negative and use EI 25 as you suggest. I'm sure others have plenty of experience with the Pyro developer, but isn't DK72 the same as Dektol?
    Kodak's DK72 is the same basic Metol/Hydroquinone (MQ) formulation as Kodak Dektol. I don't have D Log E curves for Efke 100 and Efke 25 in DK72.

    I do have D Log E curves for Efke 100 and Efke 25 developed in Ansco 130 diluted 1:20.

    I also have D Log E curves for Efke 100 and Efke 25 developed in Pyrocat-HD.

    I would recommend developing in Pyrocat-HD for contact printing. However, dilute Ansco 130 produces interesting tonalities with these films that are different from Pyrocat's.
    Tom Hoskinson
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  9. #9
    Ole
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    Quote Originally Posted by gma
    DIN 18 is ASA 50. Three numbers higher 21 is ASA 100. DIN 24 is ASA 200, etc.

    Correct, as far as it goes. there's a bit of confusion floating around as to the correct conversion from °DIN to ASA and ISO - probably stemming from that they were determined in quite different ways. It is generally considered that 18°DIN is ASA 64, while 17°DIN is ASA 50 or ISO 50/17°. BTW, the DIN number should have a "degrees" in front of it, after the number, to be entirely correct. just as on the double-barrel ISO designation

    I guess this isn't the time to bring up GOST and °Scheiner?
    -- Ole Tjugen, Luddite Elitist
    Norway



 

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