First Effectiv-Film-Speed Testing; Problems

Discussion in 'B&W: Film, Paper, Chemistry' started by gmfotografie, Mar 10, 2013.

  1. gmfotografie

    gmfotografie Member

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    hello together,
    it was a heavy rainy day so i took my camera yesterday and make some photos for first testing the film speed.
    (once i get the stouffer steps i will do the tests as lambrecht/woodhouse descripes in their book)

    but for now, i did it simple.

    i mesaure a gray carton outside with the minolta spotmeter f and analyzed those negatives with a transmission densitometer:

    the results

    0 0,01
    I 0,16
    II 0,22
    III 0,35
    IV 0,53
    V 0,67 ( f11 1/30)

    zone 0 was made with a lens cap
    zone 1-5 with diffrent times whereas zone i was 1/500

    the diffrence between zone 0 to zone 1 is massiv. do i have a problem with my camera?
    how ill you interpret those results?

    best michael
     
    Last edited by a moderator: Mar 10, 2013
  2. David Allen

    David Allen Member

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    Hi Michael,

    Your mistake was using the lens cap for the Zone 0 test. All your other Zone tests will include lens flare, the true nature of your apertures and shutter speeds, etc.

    The real key to testing a film/developer combination is to use a consistent and repeatable system. For your information, here is the testing system that I have taught for many years:

    Now the key to achieving consistently good negatives is the correct placement of your shadows when exposing the film and ascertaining the correct development time for achieving good separation without losing the highlights. A simple and relatively quick way to way to pin all this down for the future is to do the following (WARNING: reading these instructions is more time consuming and a lot more laborious than actually doing it!!):

    1. Find a scene with with a good range of tones
    2. Using the box speed, meter the darkest area in which you wish to retain shadow detail
    3. Move the camera so that you are only photographing this shadow area
    4. From the meter's reading close down the aperture by 2 stops or increase the shutter speed by two stops and then expose 6 frames at: the given exposure then +1 stop, +2 stops, -1 stop, -2 stops and -3 stops less than the meter has indicated

    5. Process the film

    6. Using the frame that was exposed at -3 stops less than the meter indicated (which should be practically clear but will have received lens flair and fogging - i.e a real world maximum black rather than an exposed piece of film that has processing fog) and do a test strip to find out what is the minimum exposure to achieve maximum black - Print must be fully dry before assessing this
    7. Do another test strip with the first exposure being what you have selected for achieving maximum black minus your dry-down compensation then plus 1 second, 2 seconds, etc
    8. The time that achieves full black inclusive of compensation for dry-down is you minimum exposure to achieve maximum black for all future printing sessions - print must be fully dry before assessing
    9 You now know the minimum time to achieve full black inclusive of exposure reduction to accommodate dry-down
    10. Using this minimum exposure to achieve maximum black exposure time, expose all of the other test frames.
    11. The test print that has good shadow detail indicates which exposure will render good shadow detail and achieve maximum black and provides you with your personal EI for the tested film/developer combination

    12 If the negative exposed at the meter reading gives good shadows, your EI is (when metering shadows where you wish to retain good detail) the box speed (i.e. for 400 film you need to set your meter at 400)
    13. If the negative exposed at +1 stop more than the meter reading gives good shadows, your EI is (when metering shadows where you wish to retain good detail) 1/2 the box speed (i.e. for 400 film you need to set your meter at 200)
    14. If the negative exposed at +2 stops more than the meter reading gives good shadows, you EI is (when metering shadows where you wish to retain good detail) 1/4 box speed (i.e. for 400 film you need to set your meter at 100)
    15. If the negative exposed at -1 stop less than the meter reading gives good shadows, you EI is (when metering shadows where you wish to retain good detail) double the box speed (i.e. for 400 film you need to set your meter at 800)
    16. If the negative exposed at -2 stop less than the meter reading gives good shadows, you EI is (when metering shadows where you wish to retain good detail) 4x the box speed (i.e. for 400 film you need to set your meter at 1600)

    You have now fixed your personal EI but there is one more testing stage to go.

    1. Find a scene with with a good range of tones
    2. Using your EI, meter the brightest area in which you wish to retain highlight detail
    3. Move the camera so that you are only photographing this highlight area
    4. From the meter's reading open up the aperture by 3 stops or decrease the shutter speed by three stops
    5. Expose the whole roll at this setting
    6. In the darkroom, process one third of the film for recommended development time

    7. When dry put negative in the enlarger and make a three section test strip exposing for half the minimum black time established earlier, for the established minimum black time and for double the minimum black time.
    8. Process print and dry it.
    9. If the section of the test strip exposed for 1/2 the minimum black time gives bright highlights with a trace of detail then the film requires 20% more development
    10. If the section of the test strip exposed for the minimum black time gives bright highlights with a trace of detail then the film is correctly developed
    11. If the section of the test strip exposed for double the minimum black time gives bright highlights with a trace of detail then the film requires 20% less development
    12. You can use the rest of the exposed highlight test film to fine tune the development time.

    YES - it is VERY boring but . . .for the investment of minimal materials and a few of hours you will have pinned down so many variables that it is really worth doing.

    Back in the real world, all you need to do in future is meter the shadows that you wish to retain good detail with meter set at your EI and then stop down the aperture 2 stops or increase the shutter speed by 2 stops. In the darkroom start your first test print with the minimum exposure to achieve maximum black (inclusive of dry-down compensation) and go from there.

    Best,

    David
    www.dsallen.de
     
  3. ic-racer

    ic-racer Member

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    You zeroed the densitometer to the zone 0 (blank) image right? If so then you can rate the film a little faster and try again. Usually one tries to get the zone I image to a log d of 0.10 rather than 0.16 that you got.
     
  4. gmfotografie

    gmfotografie Member

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    @David;
    Thanks for you tipps; I will do your test run soon for comparison


    So i did it again; but without Zone 0 with a lens cap :smile:

    First Question:

    These are the results after Zone V placing f8 1/15 -> ISO 400
    (Base+Fog Measuring to zero)
    Zone 0 (1/500) 0,05
    Zone I (1/250) 0,10
    Zone II (1/125) 0,25
    Zone III (1/60) 0,45
    Zone IV (1/30) 0,58
    Zone V (1/15) 0,71
    Zone IV (1/8 ) 0,88


    I did an extra exposure with Zone I whereas i reduce and increase the aperture half a step f8 -> 9,5 and 6,7


    Zone I f9,5 (1/250) 0,06
    Zone I f6,7 (1/250) 0,15


    If I want Zone I placing at 0,15, is it right that i have to reduce the actual film speed 400 to about 320 (Minolta Spotmeter F has 1/3 increments; on my camera I´m only able to do 1/2 increments)?
    Is this a correct way of thinking?


    ------------------------------


    Question Number 2


    I also did an exposure at Zone VIII with f8 1/2 with a result of 0,85 and also with aperture f6,7 with a result of 1,01

    I´m right that after setting my lightmeter to my correct film speed ( e.g. 320); I should focusing on Zone VIII.
    Zone VIII should be about 1,25 which i can control over the development time.
    In my case I have to increase the development time for placing Zone VIII on 1,25.
    (Zone I should thus increase lightly)

    Okay ?

    Best Michael
     
  5. David Allen

    David Allen Member

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    Just wanted to point out that I am not a fan of densitometer testing of films for the Zone System. I am not a scientist or chemist and that is the reason that I promote the 'real world' testing included in my earlier posting. Afterall, we are testing to find out what our equipment / film / processing regime requires rather than the 'official' laboratory determined results the meet the ISO standard.

    Best,

    David
    www.dsallen.de
     
  6. ic-racer

    ic-racer Member

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    Yes and yes.
     
  7. gmfotografie

    gmfotografie Member

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    Last edited by a moderator: Mar 12, 2013