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  1. #11
    AgX
    AgX is offline

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    Rafal and Ralph, thank you both for your references!

  2. #12
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    i got a replythat this seems not to be a valid email address, anyone more success?
    Regards

    Ralph W. Lambrecht
    www.darkroomagic.comrorrlambrec@ymail.com[/URL]
    www.waybeyondmonochrome.com

  3. #13

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    Very interesting. Thanks for posting that summary, Rafal.

    Michael

  4. #14
    Bill Burk's Avatar
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    Quote Originally Posted by Mr Bill View Post
    Curiously, the modern speed systems have settled back on a single fixed density point being used, albeit with a specified (sort of) development contrast. If you've read Steven Benskins posts, he seems to be a fan of the "fractional-gradient speed method," which is more complicated. Stephen doesn't get much support for his viewpoint either. Just an interesting parallel.
    Even in Todd-Zakia, the 0.1 density point is explained as easier to find than the 0.3 gradient... Stephen Benskin just points out that it's the 0.3 gradient that fits the Loyd Jones print quality studies. And he shows us how to find it with the Delta-X Criterion. 0.1 density correlates to 0.3 gradient when the specified conditions are met anyway... so you really ARE using 0.3 gradient when you develop to ASA.

  5. #15
    Bill Burk's Avatar
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    Somewhere along the way, I wrote to Ron M Callender, FRPS for a copy of his booklet "Mr Driffield and Dr Hurter, Their lives & times in pictures"...

    It is a great booklet.

  6. #16
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    Quote Originally Posted by Bill Burk View Post
    Thanks Rafal!

    Must have been an interesting time. Wet Collodion was better than any dry plates, but inconvenient. Amateurs demanded the more convenient dry plates even if it meant they were slower than what the pros used. And there were general quality and consistency issues that had to be resolved too...

    (Your post led me to a preview online of .. Encyclopedia of 19th Century Photography By John Hannavy pg. 438 which briefly mentions H&D emulsion speed in a chapter on dry plate gelatin negatives)
    Not quite right. Even the first dry plates were faster than wet plates and it didn't take long for them to become much faster. The reason dry plate manufacturers resisted accurate testing was because it might interfere with the outlandish speed claims each was making to best the others. Which is faster: Extra High Speed or Ultra High Speed?"
    www.thelightfarm.com
    Dedicated to Handmade Silver Gelatin Paper, Film, and Dry Plates.

  7. #17
    Bill Burk's Avatar
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    Quote Originally Posted by dwross View Post
    Not quite right. Even the first dry plates were faster than wet plates and it didn't take long for them to become much faster. The reason dry plate manufacturers resisted accurate testing was because it might interfere with the outlandish speed claims each was making to best the others. Which is faster: Extra High Speed or Ultra High Speed?"
    Thanks for the clarification dwross,

    If anyone knows it would be you!

    Thankfully Hurter and Driffield eradicated the superlatives...

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