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  1. #1
    df cardwell's Avatar
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    Shaping the tone curve of a Rodinal Negative

    You can shape your film's tone curve by balancing exposure and development time with agitation.

    Agitation is used to control the highlights of a negative.
    More agitation raises the highlight density, less agitation lowers highlight density.

    In this system, development time places your shadows. Exposure places your midtones.

    It is effective to visualize comparative curves pivoting at Zone V rather than rising out of film base fog as is conventional in various systems. Introducing agitation as the third variable allows us to define any density as a 'speed point'.

    This system of exposure and development was common in the early 20th century, and was often referred to as 'standing', or 'minimal', or 'tank ' development. The principle has often been called 'compensation', although I observe that compensation is due less to special properties of developers and due almost entirely to certain films like Tri-X and TMY2 which are designed to hold information when given a great deal of extra exposure.

    NB. Standing agitation is a misnomer. Few old timers ever witheld agitation completely over long periods of time, as is often attempted today. The necessity of agitation was well documented and understood. The use in this test of 5 minute resting cycles is safe, in my experience with Rodinal, for 35mm and 120 negatives and steel reels. Some experts limit their cycles to 3 minutes. Little is gained, I have found, by using longer resting cycles while the risk of negative defects are increased.

    In the illustration are two curves which demonstrate the effect of using agitation, time, and exposure to shape a tone curve. Rodinal was diluted 1+50, and used at 68˚. The blue curve shows TMY2 developed for 11 minutes, and receiving 10 seconds of agitation every minute. The red curve shows TMY2 developed for 16', agitated for 10 seconds at the beginning, 10 seconds at the 5th minute, and 10th minute.

    The curves have been adjusted left to right to represent matching mid tones by varying exposure. I am a portraitist, and mid tones are essential to me. You may match curves however you wish.

    The red curve shows greater shadow detail, and slightly higher highlights, although in practice, the highlights print identically by adjusting the print developer or filtration with variable contrast paper. The extra shadow density is the object of the exercise.

    Rodinal is an excellent developer with this technique. You may use many other developers with this method. Pyrocat, FX2 and dilute XTOL are some of many good choices.

    *** I forgot to mention that I needed to move away from contrasty developers like Dektol to print these slightly higher density negatives.

    LPD works perfectly, and the red curve will print on Ilford FB MG just right. Ansco 130 (minus HQ), D52/Selectol, a blend of Detktol and Selectol Soft (David Vestal's Delectol !) all work well.


    I have withheld the speed rating of the test film. The intent of this short article is simply to illustrate the principle while not introducing yet another 'magic bullet'. It is better to do this work without a densitometer, and judge the results by making contact prints. After all, if you see a difference, there IS a difference. If you are interested in this method, try it out ...find your own way! You are, after all, your own magic.

    For the technically minded, the curves were created by projecting a Stouffer step wedge into a 35mm camera,
    then reading the developed strips with a graphic arts baseboard densitometer. I used a Durst L1200 enlarger, an Apo EL Nikkor lens, and a Nikon F4 camera. The film was exposed at 1/125, several negatives were read, averaged, and plotted.
    It is a remarkably flare-free system.
    Last edited by df cardwell; 12-17-2009 at 12:31 PM. Click to view previous post history.
    "One of the painful things about our time is that those who feel certainty are stupid,
    and those with any imagination and understanding are filled with doubt and indecision"

    -Bertrand Russell

  2. #41
    Thomas Bertilsson's Avatar
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    Willie Jan, I make every effort to make the negatives perfect, but it's not always perfectly perfect. And that's fine. Some tweaking is to be expected in printing, I think.

    But to me, the more effort I put into understanding my materials, the more I get out of them, and the printing and post production gets so much easier! Do I get a better print? Yes. I can make a print that's almost as good from a less pristine negative, but it will take longer, and I will use more paper to get there. To me that is a struggle and I feel like I am wasting paper because I didn't get the negative right.

    So, to me it's worth the effort, but I don't have to put in a whole lot of effort either. All I do is adjust the agitation, and subsequently the development time, to get a nice negative. I don't do anything else to it. It's actually a pretty simple system based on fairly approximate metering and development adjustments.
    "Often moments come looking for us". - Robert Frank

    "Make good art!" - Neil Gaiman

    "...the heart and mind are the true lens of the camera". - Yousuf Karsh

  3. #42
    Willie Jan's Avatar
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    Quote Originally Posted by Thomas Bertilsson View Post
    Willie Jan, I make every effort to make the negatives perfect, but it's not always perfectly perfect. And that's fine. Some tweaking is to be expected in printing, I think.

    But to me, the more effort I put into understanding my materials, the more I get out of them, and the printing and post production gets so much easier! Do I get a better print? Yes. I can make a print that's almost as good from a less pristine negative, but it will take longer, and I will use more paper to get there. To me that is a struggle and I feel like I am wasting paper because I didn't get the negative right.

    So, to me it's worth the effort, but I don't have to put in a whole lot of effort either. All I do is adjust the agitation, and subsequently the development time, to get a nice negative. I don't do anything else to it. It's actually a pretty simple system based on fairly approximate metering and development adjustments.
    If I look at my pictures i printed 3 years ago, I almost fall onto the ground from laughing. I also spent half a year getting into the material. I see it as improving 5% here, 5% there... eventually getting an much more improved print.

  4. #43
    Thomas Bertilsson's Avatar
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    Same here, Willie Jan. Same here. It would be terrible if we didn't constantly be seeking improvements. We would become stagnant.

    I find that we agree on many things, and we want the same thing - beautiful prints. The road to the goal might be different, but in a way that's what makes it interesting!
    "Often moments come looking for us". - Robert Frank

    "Make good art!" - Neil Gaiman

    "...the heart and mind are the true lens of the camera". - Yousuf Karsh

  5. #44

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    DF,

    In the graph at the top of this thread the red line data is roughly the same as that of the blue line data
    between zones 4 and 6 but graphs higher than the blue for all other areas.

    What other possbilities have you been able to acheive using your methods?

    Can you independently control both ends at will?

    What are the practical limits of your control methods?

    Ray
    Be free of all deception, Be safe from bodily harm
    Love without exception, Be a saint in any form
    (Patti Smith)

  6. #45
    baachitraka's Avatar
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    http://www.apug.org/forums/forum37/9...ment-panf.html

    The thread is some how related to this how-to, can anybody have a data to share.
    OM-1n: Do I need to own a Leica?
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    Holga 120GFN: Amazingly simple yet it produces outstanding negatives to print.

  7. #46
    Jerevan's Avatar
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    I just wanted to dig up the corpse... I mean this thread and say that I have done some tests with the procedure described. And it works well.

    It was also interesting to clearly see how my preferred EI would change between different lighting conditions. Easy enough to do the test and get a lot of information in return for the work done.
    Last edited by Jerevan; 03-10-2012 at 03:56 AM. Click to view previous post history.
    “Do your work, then step back. The only path to serenity.” - Lao Tzu

  8. #47
    pierods's Avatar
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    So, when going to this method of extended time and reduced agitation with a new film, how does one find the time necessary for the film to reach the zone 5 density? (or 6, I don't understand which is the center of the pivot)

  9. #48

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    Don't forget about chromium intensifier and selenium toning. Both add more density to the highlights than the shadows. If one underdevelops a bit and utilizes one of these techniques their negs will have straighter/longer H&D curves. I preferred selenium.

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