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  1. #21

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    Speed

    Bruce-yes I get box speed from this combo. It's 120 so yoour going to have to try the 35mm. Hey I just bought some of the High Resolution film at the conference...move over Acros....
    Best, Peter

  2. #22
    Maine-iac's Avatar
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    Quote Originally Posted by dancqu
    That little phenidone for four rolls? By my math, for the
    liter, that is a .0025 % solution of phenidone. The amount
    being .025 grams. That works out to .00625 grams/roll.
    Are you sure so little will do?

    On another tack. That less than 0.01 gram of phenidone
    in hundreds of milliliters of water will in a few minutes fully
    engulf and reduce all the necessary silver halid grains
    needed to make an image.

    And to think I've been saying I use fixer very dilute. Dan
    Yep. Works just fine. Actually, that's probably more Phenidone than I need. I got the basic ratios of that formula from some old Photo Techniques article that Pat Gainer wrote, but I believe (though I may be mistaken) that he subsequently determined that the optimum ratio of Phenidone to ascorbic acid was 1:40. But I've never bothered to change since I love the results I get now.

    Larry

  3. #23

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    Quote Originally Posted by Maine-iac
    Yep. Works just fine. Actually, that's probably more
    Phenidone than I need. ... Pat Gainer ... determined
    that the optimum ratio of Phenidone to ascorbic acid
    was 1:40. But I've never bothered to change since
    I love the results I get now. Larry
    Phenidone is certainly some Fantastic developing agent.
    Almost none is required. One formula I encountered for a
    one liter concentrate uses 1 gram of phenidone. That liter
    is to make 50 liters working strength; .02 grams per liter.
    No mention though of a liter's working strength capacity.

    IIRC, Mr. Gainer's interest was with the regenerative
    aspect of the ascorbic acid-phenidone pair. Ratios
    above 1:40 did little to further increase activity.
    That is not though the only basis for deciding
    upon a specific ratio. Dan

  4. #24
    Maine-iac's Avatar
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    One liter of my formula might even develop more than four rolls of film; I've just never tried it. Since I have a two-reel (120) tank, if I've got four rolls to run at one time, I develop the first two rolls at my usual time (6:30 for Delta 400), then load the other two rolls and run them through, increasing the time about a minute. I can't tell any visual difference between the two runs. I'm fairly certain that if I did a third run and increased the time a bit more, the capacity would be there to develop them just fine too. The Phenidone/Ascorbic acid combo is potent. And it's so simple, cheap and convenient as well--three ingredients counting the alkali, and by switching between metaborate and carbonate for different films, it's also very versatile.

  5. #25
    Steve Smith's Avatar
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    Processed two rolls of 120 Acros 100 this weekend in Ilford LC29. The data I found for this combination was 4-1/2 minutes at 1:19. As this was for ISO80 and I had exposed for ISO100, I developed for 5 minutes - negatives looked great (as do prints!).

    Steve Smith.

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