Page 11 of 17 FirstFirst ... 910111213 ... LastLast
Results 101 to 110 of 167

Thread: Film test results

  1. #101

    Join Date
    Dec 2009
    Location
    Pacifica, CA
    Posts
    1,710

    Re: Film test results

    The biggest difference between the Zone System and the standards that give us ASA speeds and time and temperature recommendations...

    Is the difference between specifics and averages.

    The Zone System is based on metering specific light values that actually exist in a specific photograph and developing as needed for that specific photograph.

    While the standards system is based on statistical study of average subjects and developing as needed to satisfy viewers of the best prints that can be made from the average negatives.

    The different systems came about approximately the same time, but from ideas of different foundations.

    In fact, Leigh is right about there not being 7 Zones. The fact that common practice may deal with 7 Zones is an attempt to reconcile the two different systems. Minor White called N development as the baseline which includes Zones 0 and VIII which you might call 8 or 9 steps or zones depending how you count. The fact it worked is that Minor White had you work from pitch black to pure white on the print.

    The idea of working with Zones II to VIII came later and probably part of reconciliation to make Zone System more practical as it evolved.

  2. #102
    8x10, 5x7, 4x5, et al Leigh's Avatar
    Join Date
    Dec 2010
    Location
    Maryland, USA
    Posts
    5,454

    Re: Film test results

    I find comments to the effect that a step tablet is not a "real world" subject to be amusing.

    Suppose you're shooting step tablets for Stouffer for its ads for step tablets.

    There is no such thing as a "phony" subject. Whatever sits in front of the lens is "valid".

    - Leigh
    If you believe you can, or you believe you can't... you're right.

  3. #103

    Join Date
    Dec 2009
    Location
    Pacifica, CA
    Posts
    1,710

    Re: Film test results

    Leigh,

    Once again, you are right! The difference is not that important. Even if the difference accounted for 2/3 stop, it's consistent. Plus 2/3 stop is not enough to worry about when there are so many other things that are bigger influences on exposure errors. I think it might make a good thread to talk about those.

    The issues that may arise from a step tablet are whether they are shot as a photograph from a window-pane, in which case there is flare that keeps toe from properly reaching zero... Or whether it's contacted, in which case the true characteristics of the film are being revealed (with the caveat that the light source had to be a compromise because the necessary science to re-create sunlight in the lab is rather hard to control - I for instance settle for an electronic flash tube, others may prefer a tungsten bulb with an 80B blue filter).

  4. #104
    8x10, 5x7, 4x5, et al Leigh's Avatar
    Join Date
    Dec 2010
    Location
    Maryland, USA
    Posts
    5,454

    Re: Film test results

    Hi Bill,

    I get around the "artificial sunlight" problem by shooting only b&w.

    Of course, I do use panchromatic (sort of) film.

    - Leigh
    If you believe you can, or you believe you can't... you're right.

  5. #105

    Join Date
    Jul 2008
    Location
    Los Angeles
    Posts
    212

    Re: Film test results

    A change in the suggested color temperature of the light source in sensitometers changed the b&w film speed equation from 1.0 / Hm to 0.80 / Hm or a 1/3 if a stop compensation. I believe the change was from Sunlight to Daylight balance.

  6. #106
    Drew Wiley
    Join Date
    Sep 2008
    Location
    SF Bay area, CA
    Posts
    18,338

    Re: Film test results

    Not all panchromatic films are in fact identical in spectral sensitivity. And spectral sensitivity can even shift at long exposures versus short exp. There are tons of potential variables neither ordinary speed ratings nor the ZS take into account. And one can factor in as many "Zones" to a shot as one damn well pleases. These aren't the laws of physics, just tools meant to be adapted to personal requirements. And you can make any of this either as complicated or a simple as you need. ...

  7. #107

    Join Date
    Sep 2009
    Location
    San Francisco, CA
    Posts
    503

    Oooookay, let's get back to the point

    I know that in the age of the internet, posts become part of the public domain. In other words, one no longer owns the post one started. However, I'm going to take some ownership and continue my discussion.

    So I moved on to N time testing. After giving it some thought, I decided that my findings (EI 160) for Delta+DDX were correct and proceeded from there.

    I shot a real life scene with zones V, III, and VIII in them. I shot this three times (the exact same thing, checking before the exposure to make sure the lighting had not changed: it hadn't). I processed each exposure with an EI of 160 for 12 minutes. I kept all temperatures consistent at 20 C (a degree or two + or -, no more than that). I developed each sheet of film at different times, 100% of the time, 85% of the time, and 115% of the time. However, I did not process a blank sheet of film with each exposure. I simply forgot, so I don't have a reading for fb+fog for each time. Well, except 100%, which, taking my results from my EI testing, is 0.17. Other than that, I don't have any results for 85% or 115%.

    Here are my results:

    Ilford Delta 100 (EI 160) 4x5 and DDX (1:4)
    20 C, 12 minutes, intermittent agitation
    Zone V (an actual grey card): f/5.6, 1/8; Zone III (a black backpack): f/2.8, 1/8; Zone VIII (a white wall): f/16, 1/8
    I shot all three scenes at f/5.6 for 1/8 of a second (exposing for the gray card).
    100% = 12 minutes; 85% = 10 minutes, 12 seconds; 115% = 13 minutes, 48 seconds.

    85% 100% 115%
    V 0.89 1.05 1.08
    III 0.41 0.46 0.46
    VIII 1.69 1.96 2.07

    Those readings were made using a sensitometer. Oh, and those readings are of the negatives. Of the areas representing zones V, III, and VIII. I remember when I did this testing in a class I took, we read the negatives for the densities, however, now, in the handouts from that class, I can't find what the densities are supposed to be. All I can find are what the densities are supposed to be on a print/enlargement. I also checked The Negative and AA only gives the densities for the print--not the negatives.

    I hope I can still use these results even without fb+fog readings.

    Thanks.
    --Mario

  8. #108

    Join Date
    Oct 2012
    Location
    Boulder, co
    Posts
    627

    Re: Film test results

    Certainly perception will change how people see a scene. but I think that is irrelevant when discussing the principles of the systems, especially since many exposure is based largely on what the meter reads and the meter is most definitely color blind.

    the question remains
    Why are the calibration goals of the two systems different?

    Leigh, are you suggesting adams' perception was predisposed towards a broader NDR printed on grade 2 paper? if so then it is important to bring that out and lay out a calibration system that does not duplicate that decision, but rather allows individuals to find the 'look' that suits them.


    a thought came to me that shooting for a larger NDR gives one more control at the printing stage, and that going to thin results in compressed tonality that can't be easily 'rescued' in the print in some way. I'm not sure I said that very clearly....
    I said that maybe adam's liked a broad NDR (1.25) printed on a grade 2 (LER 1.05). perhaps he could see into the shadows, or perhaps he liked to separate shadows more so that he could then dodge and reveal the important ones. I'm wondering if zone system is as it is, not because it seeks to predetermine contrast, but rather because it seeks to have a little extra information spread over the negative. Make sense?

    So while kodak wants to get technically good prints by imposing a set dev and print scheme after exposure, the Zone systems continues to play with the image, and final execution and look is determined at printing, where certain details are either sacrificed or skilfully revealed.

    I think it could be an answer to the question, but I am sure Stephen has another one in mind.
    ~nicholas
    lifeofstawa
    stawastawa at gmail

  9. #109
    8x10, 5x7, 4x5, et al Leigh's Avatar
    Join Date
    Dec 2010
    Location
    Maryland, USA
    Posts
    5,454

    Re: Film test results

    Quote Originally Posted by stawastawa View Post
    Certainly perception will change how people see a scene. but I think that is irrelevant when discussing the principles of the systems, especially since many exposure is based largely on what the meter reads and the meter is most definitely color blind.
    Individual perception is absolutely critical to application of the ZS to negative exposure.
    It's up to the shooter to place a particular scene feature on a particular zone.
    That determination depends on personal factors unrelated to the meters.

    The meters and the film emulsion definitely ARE NOT uniformly sensitive over the entire visible spectrum.

    Quote Originally Posted by stawastawa View Post
    Why are the calibration goals of the two systems different?
    Why should any two systems agree? If they did, they would merge and there would be only one system.

    Quote Originally Posted by stawastawa View Post
    Leigh, are you suggesting adams' perception was predisposed towards a broader NDR printed on grade 2 paper? if so then it is important to bring that out and lay out a calibration system that does not duplicate that decision, but rather allows individuals to find the 'look' that suits them.
    The calibration steps built into the ZS are the factors that "personalize" the system for each individual shooter.
    Those steps also eliminate personal errors in use of spot meters, and errors in the meters themselves, which can be rather large. Also, as I've mentioned before, these can compensate somewhat for color blindness of the shooter.

    The ZS does not lock anybody into any particular set of values, unless one chooses to be so constrained.
    There is sufficient variability built into the system to allow any shooter to tailor it as needed to produce the desired results.

    - Leigh
    If you believe you can, or you believe you can't... you're right.

  10. #110

    Join Date
    Oct 2012
    Location
    Boulder, co
    Posts
    627

    Re: Film test results

    Quote Originally Posted by Leigh View Post
    Why should any two systems agree? If they did, they would merge and there would be only one system.
    - Leigh
    I'm not saying they should agree, but it is curious that both systems seek to print on a grade 2 paper and yet choose different NDRs. The reason for why that NDR is recommended should be identifiable.
    ~nicholas
    lifeofstawa
    stawastawa at gmail

Similar Threads

  1. Aardenburg archival test results....?
    By Kirk Gittings in forum Digital Hardware
    Replies: 10
    Last Post: 26-Sep-2010, 10:27
  2. Film Test Results
    By Tony Flora in forum Darkroom: Film, Processing & Printing
    Replies: 22
    Last Post: 6-Oct-2008, 11:24
  3. Some lightfastness test results
    By paulr in forum Darkroom: Film, Processing & Printing
    Replies: 5
    Last Post: 29-Aug-2006, 09:48
  4. Rollei infrared film test results
    By Jonathan Brewer in forum Lenses & Lens Accessories
    Replies: 2
    Last Post: 27-Jul-2006, 22:35

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •