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  1. #1
    PeterB's Avatar
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    Camera+Film+FilmDeveloper Process Control idea for Zone System followers

    Hi folks,

    As a Zone System practitioner I would like a relatively quick way to ensure that the process variables for my camera, film and film developer are "in control". I would like to propose a method to do this and would appreciate your feedback on its pros and cons.

    BTW I don't (yet?) own a sensitometer nor have I purchased any KODAK Black-and-White Film Process Control Strips (CAT 180 2990). They would only test out that my film development process was in control, so instead with the following suggestion you can widen the net and include your own film plus camera system too.

    Aim:
    To expose a roll of film with 3 frames, each frame being a shot of the same grey surface (not necessarily 18% grey) exposed to Zones III, V and VII by only varying the camera's aperture. Process the film for N development, then measure the density of each frame to see if it matches your previously determined density targets for those zones at N development. You of course will need to have previously determined these densities using your favourite ZS methodology, and thus be in possession of a densitometer.

    Method:
    1. Find any mid grey surface to mostly fill the frame of your favourite format.
    2. Expose frame 1 for Zone III using your light meter. Choose a shutter speed on your camera that you have measured to be within 10% of its nominal value. Use either f22 or f16.
    3. Expose frame 2 for Zone V using the same shutter speed as step 2 and opening up the aperture to either f11 or f8.
    4. Expose frame 3 for Zone VII using the same shutter speed as step 2 and opening up the aperture to either f5.6 or f4.
    5. Ensure the light level hasn't changed between steps 2 and 4.
    6. Process film for N development.
    7. Measure the transmission density of each frame and ensure it matches your expectations to within your acceptable margin of tolerance (say +/- half a zone). You should understand the Zone system to know where those densities should fall.

    A possible variation is to take 3 frames of each zone to check for variability of your shutter timing.


    The advantage of this method is that:
    • It is less sensitive to flare you would get by having say a test surface/card with the three different Zones on it at once.
    • You also don't have to create or maintain such a 3 zoned surface which takes more time and relies on the accuracy of your light meter in high flare conditions to ensure the surface was calibrated.
    Last edited by PeterB; 04-12-2013 at 12:26 AM. Click to view previous post history. Reason: typo for aperture direction and values

  2. #2
    dpurdy's Avatar
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    For my quick tests I generally only worry about Z1 and Z7... film speed and development time.
    I do have a densitometer but am often too lazy to warm it up. I have a sheet of film that I know reads 1.2 that I keep on my light table for quick visual comparisons to my test Z7 and I have pretty good memory recognition of Z1.
    As you are using the Zone system I assume you have a spot meter. You can use your spot meter as a quick rough density checker if you have a good size piece of film at a known density you can put on a light table. Make a snoot for your spot meter to block flare light from the light table.
    Dennis

  3. #3
    PeterB's Avatar
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    Thanks Dennis. I have both a spot meter and a densitometer. The test I propose gives a relatively quick check of ALL process variables in the system up to the processed negative.

    rgds
    Peter

  4. #4
    cliveh's Avatar
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    Quote Originally Posted by PeterB View Post
    Hi folks,

    As a Zone System practitioner I would like a relatively quick way to ensure that the process variables for my camera, film and film developer are "in control". I would like to propose a method to do this and would appreciate your feedback on its pros and cons.

    BTW I don't (yet?) own a sensitometer nor have I purchased any KODAK Black-and-White Film Process Control Strips (CAT 180 2990). They would only test out that my film development process was in control, so instead with the following suggestion you can widen the net and include your own film plus camera system too.

    Aim:
    To expose a roll of film with 3 frames, each frame being a shot of the same grey surface (not necessarily 18% grey) exposed to Zones III, V and VII by only varying the camera's aperture. Process the film for N development, then measure the density of each frame to see if it matches your previously determined density targets for those zones at N development. You of course will need to have previously determined these densities using your favourite ZS methodology, and thus be in possession of a densitometer.

    Method:
    1. Find any mid grey surface to mostly fill the frame of your favourite format.
    2. Expose frame 1 for Zone III using your light meter. Choose a shutter speed on your camera that you have measured to be within 10% of its nominal value. Use either f22 or f16.
    3. Expose frame 2 for Zone V using the same shutter speed as step 2 and opening up the aperture to either f11 or f8.
    4. Expose frame 3 for Zone VII using the same shutter speed as step 2 and opening up the aperture to either f5.6 or f4.
    5. Ensure the light level hasn't changed between steps 2 and 4.
    6. Process film for N development.
    7. Measure the transmission density of each frame and ensure it matches your expectations to within your acceptable margin of tolerance (say +/- half a zone). You should understand the Zone system to know where those densities should fall.

    A possible variation is to take 3 frames of each zone to check for variability of your shutter timing.


    The advantage of this method is that:
    • It is less sensitive to flare you would get by having say a test surface/card with the three different Zones on it at once.
    • You also don't have to create or maintain such a 3 zoned surface which takes more time and relies on the accuracy of your light meter in high flare conditions to ensure the surface was calibrated.
    What do you do if the light changes between exposures?

    “The contemplation of things as they are, without error or confusion, without substitution or imposture, is in itself a nobler thing than a whole harvest of invention”

    Francis Bacon

  5. #5
    PeterB's Avatar
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    Quote Originally Posted by cliveh View Post
    What do you do if the light changes between exposures?
    Well if you are taking it inside that shouldn't happen. If you are taking it outside you should check to see that no passing clouds will cause the local light level to change in the 2 minutes it will take you to take the 3 frames and stop open the aperture (which isn't too hard).

  6. #6

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    Some thoughts:

    I shoot sheet film and practice the Zone System. I test for many different development schemes (N, N+s and N-s). However, for roll film, when you will be shooting subjects of different contrast on the same roll, it is most important to simply find an N that gives you good shadow detail and manageable highlights. Since you use a spot meter, all you would then have to do is place an important shadow. I would deal with the different contrast situations by changing paper grade. And I would tailor my N to grade 2.5 or 3 to give a bit more latitude for high-contrast subjects.

    Your test could (and I think should) be done without a densitometer, but rather by making proper proofs of your negatives on the paper and grade you will mostly use. This takes your enlarging system into account as well.

    Furthermore, I think you should set up your targets in a situation where you would have "normal" flare. I set up a target card in a scene and like to have it take up no more than about a third of the entire scene. I use darker cards for the shadow values. That way I take an "average" amount of flare into account when making the test. Otherwise, you can test out everything and then get significantly higher shadow values in practice due to flare.

    I find keying Zone VIII as just below paper-base white to be my most important highlight benchmark, not Zone VII.

    I also like having the prints of my tests to remind me of just what I'm going to get when I place a certain value in a Zone. Densitometer readings don't help me to visualize. I used to make Zone Rulers (prints of Zone 0 through the highest Zone for a particular development scheme) to help me learn to visualize tones. I no longer need them, but they were indispensable at the beginning. One also finds that Zones for a particular scheme don't always follow the classic ZS descriptions. When Zone III and Zone VIII are perfect, Zone V is often far from 18% grey. It's more important to know what you'll get when you expose than to try to match some arbitrary standard.

    The amount of variables in a photographic system is huge and little errors add up fast. Getting to within one Zone of my desired placement/development is way close enough for me. Printing controls are more than adequate for that. Realize that even your tests can be significantly "off," and make future adjustments based on field notes and experience.

    Best,

    Doremus


    www.DoremusScudder.com

  7. #7
    PeterB's Avatar
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    Quote Originally Posted by Doremus Scudder View Post
    Some thoughts:

    I shoot sheet film and practice the Zone System. I test for many different development schemes (N, N+s and N-s). However, for roll film, when you will be shooting subjects of different contrast on the same roll, it is most important to simply find an N that gives you good shadow detail and manageable highlights. Since you use a spot meter, all you would then have to do is place an important shadow. I would deal with the different contrast situations by changing paper grade. And I would tailor my N to grade 2.5 or 3 to give a bit more latitude for high-contrast subjects.
    Thanks Doremus. I shoot the entire roll to the same scheme (N, N+s and N-s).

    Quote Originally Posted by Doremus Scudder View Post
    Your test could (and I think should) be done without a densitometer, but rather by making proper proofs of your negatives on the paper and grade you will mostly use. This takes your enlarging system into account as well.
    Wouldn't I then just be using a reflection densitometer to measure the paper densities anyway ?


    Quote Originally Posted by Doremus Scudder View Post
    Furthermore, I think you should set up your targets in a situation where you would have "normal" flare. I set up a target card in a scene and like to have it take up no more than about a third of the entire scene. I use darker cards for the shadow values. That way I take an "average" amount of flare into account when making the test. Otherwise, you can test out everything and then get significantly higher shadow values in practice due to flare.
    I considered your suggestion, and this is certainly one way to account for real life flare. The way I prefer to do it is to slightly increase the negative density range (by about 0.1 units) for a given SBR. i.e. increase CI/gamma. I suspect this is no more or less better at compensating for flare than you method, just a different way.

    Quote Originally Posted by Doremus Scudder View Post
    I also like having the prints of my tests to remind me of just what I'm going to get when I place a certain value in a Zone. Densitometer readings don't help me to visualize.
    That sounds a good idea.

    I used to make Zone Rulers (prints of Zone 0 through the highest Zone for a particular development scheme) to help me learn to visualize tones. I no longer need them, but they were indispensable at the beginning. One also finds that Zones for a particular scheme don't always follow the classic ZS descriptions.

    Quote Originally Posted by Doremus Scudder View Post
    When Zone III and Zone VIII are perfect, Zone V is often far from 18% grey.
    I've always wondered about the non linear nature of intermediate zones. I also experience that.

    You also mentioned using Zone VIII instead of VII. That is easy to do with my proposed method if you have a large enough aperture range. I initially wanted to ensure most aperture ranges could be catered for.

    regards
    Peter

  8. #8
    Jim Noel's Avatar
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    The north side of a building works well for this. If it has texture,such as stucco, so much the better. Develop together.
    [FONT=Comic Sans MS]Films NOT Dead - Just getting fixed![/FONT]

  9. #9
    Bill Burk's Avatar
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    I'm a big fan of sensitometer/test strips from step wedges contacted on film. I would go that route if flare-free testing was my aim. Though you are right, the suggested test of a single-tone target would be relatively flare-free.

    There is no definition correlating density to a particular Zone, but this doesn't mean you can't use three arbitrary exposures to base a custom "test strip" upon. You can pick any two, three or more steps. Heck, you could do an impromptu test anywhere you go on the first roll of the day... Meter at f/5.6... Open to 2, shoot, stop down a stop, shoot, and quickly fire off 5 or more frames a stop apart.

    Then when back from the day, develop that roll and see whether it's good for that camera/lighting conditions/day. If so, develop the rest of the rolls, if not tweak up or down a minute or two according to your preferences...

  10. #10

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    Quote Originally Posted by PeterB View Post
    Thanks Doremus. I shoot the entire roll to the same scheme (N, N+s and N-s).
    Well then, of course you would want different development schemes. Whenever I shoot roll film (and that's a rarity these days) I usually have different contrast situations on one roll.


    Quote Originally Posted by PeterB View Post
    Wouldn't I then just be using a reflection densitometer to measure the paper densities anyway ?
    No, you'd use your eyes to tell you if you got the desired print values. As you can see, I prefer a visual approach to testing that takes the final print into consideration. I never measure the densities of prints I make in order to decide what value it should be; I use my eyes. Same for testing.


    Quote Originally Posted by PeterB View Post
    I considered your suggestion, and this is certainly one way to account for real life flare. The way I prefer to do it is to slightly increase the negative density range (by about 0.1 units) for a given SBR. i.e. increase CI/gamma. I suspect this is no more or less better at compensating for flare than you method, just a different way.
    Again, I don't want to test for just one variable, nor do I really want to collect data; I just want to know how what I meter will end up in the print, visually. Therefore the test of the entire system as a "black box," not the individual aspects.

    Quote Originally Posted by PeterB View Post
    I've always wondered about the non linear nature of intermediate zones. I also experience that.
    I think that for ZS practitioners, realizing this is an important step in getting to know your materials and the process, not to mention helping you to better know what you'll get when you place something in a particular Zone.

    Quote Originally Posted by PeterB View Post
    You also mentioned using Zone VIII instead of VII. That is easy to do with my proposed method if you have a large enough aperture range. I initially wanted to ensure most aperture ranges could be catered for.
    I find that finding my Zone VIII, which I define as the first noticeable grey with a hint of texture (i.e., a non-specular white) is a better and easier to pinpoint benchmark than a "fully-textured off white/concrete color" Zone VII. That and the Zone III (first black with real texture) give me the endpoints of my system. Then I test to see where the other Zones will end up. I often make a Zone ruler to be able to visualize this more easily for, as already mentioned, the intermediate Zones are not always linear.

    Best and good luck testing.

    Doremus

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