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  1. #11
    David Lyga's Avatar
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    Am I naive here? "X" = "TIMES". Double X was 2 times the 'standard' speed and Tri-X is three times the 'standard' speed. Plus-X is a bit faster than the 'standard' speed since 125 is a bit faster than 100. And NO, Tri-X is not 400 but really about 300. Panatomic-X I do not have an answer for. But, again, maybe none of my answers were real answers! - David Lyga

  2. #12
    MattKing's Avatar
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    Quote Originally Posted by pentaxuser View Post
    I think we need a Kodak source called PE There has to be a kind of reasoning behind the use of X doesn't there?

    pentaxuser
    I don't think PE is old enough to know.

    Happy New Year PE
    Matt

    “Photography is a complex and fluid medium, and its many factors are not applied in simple sequence. Rather, the process may be likened to the art of the juggler in keeping many balls in the air at one time!”

    Ansel Adams, from the introduction to The Negative - The New Ansel Adams Photography Series / Book 2

  3. #13
    zsas's Avatar
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    Quote Originally Posted by Bill Burk View Post
    I don't know but guess that it goes back to the glass plate speeds...

    Slow, Ordinary, Rapid, Extra Rapid, Double Extra Rapid.

    Where the X is from Extra.

    I've had a hard time finding how these speeds translate to ASA/ISO speeds. Seems any reference that knows these speeds predates ASA...
    Think you might have it (just my guess after finding the below Kodak ad from '39 announcing three new films PlusX, SuperXX, PanatomicX)....

    http://farm5.staticflickr.com/4148/5...8ccd0a74_o.jpg
    Andy

  4. #14

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    Well in Microdol-X the X represents the inclusion of the secret mercapto. Do a APUG search about Microdol-X where PE and I go back and forth about the mercapto.

  5. #15
    zsas's Avatar
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    So X is just a varriable used time to time to differentiate Y we think? Kinda like Super XX is to Plus X as mercepto leads to Microdol X
    Andy

  6. #16
    darkosaric's Avatar
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    Quote Originally Posted by David Lyga View Post
    Am I naive here? "X" = "TIMES". Double X was 2 times the 'standard' speed and Tri-X is three times the 'standard' speed. Plus-X is a bit faster than the 'standard' speed since 125 is a bit faster than 100. And NO, Tri-X is not 400 but really about 300. Panatomic-X I do not have an answer for. But, again, maybe none of my answers were real answers! - David Lyga
    This sounds very logical to me.

  7. #17

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    David's explanation sounds as if it may be right. In those far-off days we spoke about the "times tables" referring to multiplication tables and people were used to the X symbol to mean the instruction "multiple"

    pentaxuser

  8. #18
    zsas's Avatar
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    ^ But David's theory doesn't work on the Microdol-X example....thinking X is used to mean Y....whatever that Y maybe
    Andy

  9. #19
    Bill Burk's Avatar
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    I found an exposure chart and worked backwards from "Sunny 16" to find what I think might have been "equivalent" ASA speeds for the different plates.

    There wasn't as much difference between the speeds as I thought there would be... Maybe this is why they tried to run Hurter and Driffield out of town...

    Photographic News for Amateur Photographers, Volume 51


    Ordinary Plate EI appx 1.25

    Medium Plate EI appx 2

    Rapid Plate EI appx 3.75

    Extra Rapid Plate EI appx 5.00

    Ultra Rapid Plate appx EI 6.25

  10. #20

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    if you substitute "speed" for "x" in the old film ad andy posted
    super speedy speed,
    plus speed, panATOMIC speed

    its just futuristic babble
    its the 30s, post industrialism,
    art deco at its finest ...

    wasn't the bromoseltzer guy's sub atomic plane
    powered by bromo X ...

    i think the guys from MST3K might know for sure ...
    if my apug gallery looks empty you might check these places

    website
    blog
    sell-site

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