Film speed test. Need help in understanding my results.

Discussion in 'B&W: Film, Paper, Chemistry' started by kjsphoto, Jan 22, 2005.

  1. kjsphoto

    kjsphoto Subscriber

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    I am lost, here are my results.

    First I am using a spot meter as I do not have a densitometer and I do not have a lab in the area that I woudl use one so I am trying to figure it out with a spot.

    The FILM is ACROS 100;

    I think the film speed is 80 though but I do not really know what to do as I think the dev time is too short for zone VIII

    Light Box f11.3-4
    Blank Frame f8.07

    2/3 difference gives a density of .2 each 1/3 in fstop = .1 in density change according to the directions on this site;
    http://www.zone2tone.co.uk/testingm.htm#film_speed

    But I am just so confused.

    Here are my reading for each neg for Zone 1 & Zone VIII targets

    Frame1 f8.0.5
    Frame2 f8.0.6
    ***Frame3 f8.0.3 Zone 1 target
    Frame4 f8.0.0
    Frame5 f2.8.0
    Frame6 f2.8.3
    ***Frame7 f2.0.6-7 Zone 8 target
    Frame8 f2.0.4

    So a .1 difference from blank frame would be frame 3, 1/3 stop.

    The matching frame then would be frame 7 which is 4 stops.

    Am I good or do I need to add more time to development? Or am I doing this completely wrong??

    Thanks,

    Kev
     
  2. dancqu

    dancqu Member

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    I think you should start at the begining; some detail on how
    you exposed, the equipment, and how developed. Dan
     
  3. kjsphoto

    kjsphoto Subscriber

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  4. pelerin

    pelerin Member

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    Hey,
    What kind of spot meter are you using? When you say "blank frame = 8.07" do you mean by that, "f8.0 and 7/10's"? (or rounding, f8.0 and 2/3's) If yes then .1 over B+F = 1/3 stop change i.e., f8.0 and 1/3. (your result) It seems to me that if you can set the meter to read out in EVs it makes this task much easier as you end up with a more intuitive sequence of #'s. I might try something like this:
    1: set meter to read in EV
    2: "calibrate your densitometer" i.e., set the ISO that the meter reads the light box as EV 12 (this is arbitrary but you need enough range to cover the density range of the film)
    3: You then get something like this:

    You could of course make the equivalent chart with f stops but my (admittedly simple) mind finds the clean progression EVs provide simpler to read. It is then relatively simple to convert the the readings of the spot meter to see if the film conforms to the recommendations. Be careful to note whether a recommended density is given as gross (i.e., the actual #) or as a range (i.e., subtract film base + fog). Does this work? Yes I have used similar trials to produce workable results. The above is gleaned from some foggy memories of a class I took c. 1994 and I got usable data. A densitometer makes life much easier.
    Celac.
    ...who begs forgiveness for any typos that render the above obfuscatory.
     
  5. kjsphoto

    kjsphoto Subscriber

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    Thank you very much. I will try the EV. Makes more scense than before!

    So make light table EV 12. ok that will make lif eaiser.

    Thank you again,

    Kev