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Thread: Zone I SET

  1. #21

    Join Date
    Jul 2007
    Location
    near Seattle, WA
    Posts
    956

    Re: Zone I SET

    Quote Originally Posted by Doremus Scudder View Post
    ...changing development time changes the film-base+fog density...
    Doremus, I’ve found something interesting in this regard. When I tested HP5+ sheet in HC-110B with step tablet in camera, measuring fb+fog at the rebate, the results agreed with your comment. Testing from 4min to 14min, the rebate showed fb+fog increasing from .16 to .22.

    Then I read an article by Howard Bond which I copied to a pdf file (attached) in which he said on p.4 (see my red font) that he measured fb+fog under a piece of electrical tape that had a small piece of aluminum foil under the tape to make sure the measured area under the tape received no exposure. So, later when I tested FP4+ in HC-110B, I followed his method for fb+fog. Testing from 5min to 9min, fb+fog was consistently .12 +/- .01. I’ve not yet redone the HP5+ tests. I suspect this is the rabbit hole you mentioned.

  2. #22

    Join Date
    Sep 1998
    Location
    Oregon now (formerly Austria)
    Posts
    3,397

    Re: Zone I SET

    Jerry,

    The real (and easier) test would be to develop strips of unexposed film for various times. I suspect that fb+fog will increase with increasing development time, though.

    Best,

    Doremus

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