Switch to English Language Passer en langue française Omschakelen naar Nederlandse Taal Wechseln Sie zu deutschen Sprache Passa alla lingua italiana
Members: 70,710   Posts: 1,548,634   Online: 1115
      
Results 1 to 3 of 3

Thread: film speed

  1. #1

    Join Date
    Apr 2006
    Shooter
    4x5 Format
    Posts
    213

    film speed

    hi
    i just finnished my new film speed test using a slosh tray from PF for 6 4X5 sheets in PMK pyro. using my old system of yankee tank insert dunked in a 3qt container my fielm speed was iso 200 w hp5+. it now showes a iso of 800 is this strange.? most people have lower film speeds not higher.
    thanks
    mitch

  2. #2
    gainer's Avatar
    Join Date
    Sep 2002
    Posts
    3,726
    Images
    2
    Are you sure this is ISO? ISO determination requires a particular procedure. It will depend on contrast, which will depend on agitation and other factors.
    Gadget Gainer

  3. #3

    Join Date
    Jul 2006
    Location
    Durham, NC
    Shooter
    Multi Format
    Posts
    306
    Images
    26
    This is probably too high for hp5. My speeds in PMK and Pyrocat are at 400. I'm not sure what process you are using to determine film speed. I shoot a grey card and expose at different speeds. Then process normally and read the exposures on a densitometer. The density that is about .1 above base+ fog determines film speed for the film/developer combination. You can then tweek development times to produce a ZV exposure (18% grey card) at about .65 + B+F density.
    This was the original approach AA used when establishing the Zone system. There are several variations, but the original method has always worked well for me.
    Don Sigl
    www.drs-fineartphoto.com



 

APUG PARTNERS EQUALLY FUNDING OUR COMMUNITY:



Contact Us  |  Support Us!  |  Advertise  |  Site Terms  |  Archive  —   Search  |  Mobile Device Access  |  RSS  |  Facebook  |  Linkedin