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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. #31
    Thomas Bertilsson's Avatar
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    Well, it works for me is all I can say. When people view my prints, print quality is certainly not something they complain about. The actual subject matter and photograph is naturally not to everybody's liking.

    I could easily print every negative I have on Ilford MGIV matte and be happy with it. I don't find that switching to other papers help me in any way. And I have tried.
    "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. #32
    clayne's Avatar
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    Re: Shaping the tone curve of a Rodinal Negative

    Thomas, do you not have shots with certain subjects and scenes that have the majority of exposure biased towards shoulder or toe? Not everything can be middle of the road, nor is everything naturally the same contrast or could be made that way. If you had a low key subject you wouldn't necessarily choose the same paper as a high key subject, right? Anyways a lot of styles of photography do not even allow liberty of choosing a well thought out exposure for the scene - many are just "good enough." I can't target a given paper by default. I can only do things to increase my options.
    Stop worrying about grain, resolution, sharpness, and everything else that doesn't have a damn thing to do with substance.

    http://www.flickr.com/kediwah

  4. #33
    Willie Jan's Avatar
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    Quote Originally Posted by Thomas Bertilsson View Post
    So how will over-exposing help, then?
    What you did was to move the tonal scale farther up the curve, and since the windows needed burning to reveal detail, your highlights got too far up the curve, into the 'difficult to print' territory.

    Either you exposed too much, or you didn't adjust your development time enough. Or both.

    It's a good thing you exposed two sheets. You came away with a nice print that works.
    I still have a neg from this situation. So I can do a 6 min test. But going to short get's other problems...
    I mostly do my process of photographing/developing in my standard way. When the light is to bright, i come back another day. When it is to low, also. Adjusting things often make things worse. I am at a point where I am looking at the final print and don't care about the neg anymore. Because my print is what I put on the wall, not a negative. Besides that I use all kind of print papers from cyanotype to baryta and PE.

    Don't loose to much time in getting the absolute perfect neg, because probably it's not printable. A friend of my says that we think that we can create a neg that can be printed without any work, but he says printing is where it starts. Every print needs adjustment to get it even better.

  5. #34
    clayne's Avatar
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    Quote Originally Posted by Willie Jan View Post
    Don't loose to much time in getting the absolute perfect neg, because probably it's not printable. A friend of my says that we think that we can create a neg that can be printed without any work, but he says printing is where it starts. Every print needs adjustment to get it even better.
    True - but we've all had negs that just print themselves. I don't think there's a perfect negative the same as I don't think there's a perfect light or perfect print. Take what you can get sometimes.
    Stop worrying about grain, resolution, sharpness, and everything else that doesn't have a damn thing to do with substance.

    http://www.flickr.com/kediwah

  6. #35

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    Quote Originally Posted by Willie Jan View Post
    because I got 8 stops of light and my paper is capable of showing 4.5 stops
    Wait, there are 2 different things:

    1) You have a medium that records an image, the negative, which is very good at what it does.
    2) Another medium that represents the information in the negative, the paper. This one will go from white to black within 4,5 stops of exposure. That doesn't mean you will only get 4,5 stops from the negative represented on the print.

    The negative has rather low contrast, but the paper has much higher. The combination can show much more than 4,5 stops of the original scene. I've done some film testing and I can show 10 different tonal values of the original scene in a print, from absolute black, to absolute white (and a condenser enlarger). I can do this by overexposing by 1 stop and pull process accordingly. That's what I do in high contrast situations only, in cloudy days the manufacturer's recommendation is just fine. That said, it doesn't mean that the negative always prints itself, some d&b might be required to get the best result.

    Now, in that specific case, if you only had 8 stops of subject brightness range, I don't think you needed to go that far. IMHO, you tried to solve a problem that didn't really exist.

  7. #36
    Willie Jan's Avatar
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    Quote Originally Posted by Anon Ymous View Post
    Wait, there are 2 different things:

    1) You have a medium that records an image, the negative, which is very good at what it does.
    2) Another medium that represents the information in the negative, the paper. This one will go from white to black within 4,5 stops of exposure. That doesn't mean you will only get 4,5 stops from the negative represented on the print.

    The negative has rather low contrast, but the paper has much higher. The combination can show much more than 4,5 stops of the original scene. I've done some film testing and I can show 10 different tonal values of the original scene in a print, from absolute black, to absolute white (and a condenser enlarger). I can do this by overexposing by 1 stop and pull process accordingly. That's what I do in high contrast situations only, in cloudy days the manufacturer's recommendation is just fine. That said, it doesn't mean that the negative always prints itself, some d&b might be required to get the best result.

    Now, in that specific case, if you only had 8 stops of subject brightness range, I don't think you needed to go that far. IMHO, you tried to solve a problem that didn't really exist.
    You are right that 8 stops is printable, but shadows and/or highlights based on your measurements will lose details.
    My basic idea is that i want to see in the photo what i saw at the scene.
    This is only possible when i make studio stillife photos where i can set the light so that it is under 5 stops. This neg can be printed without any problems.

  8. #37
    Thomas Bertilsson's Avatar
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    Sure I do, and usually because I want them to print that way. But I find that I can print anything on Ilford MGIV to my satisfaction. Granted, like everybody else I do screw up sometimes and get negs I can't print.
    But switching to other papers hasn't helped me. It has only confused me and prevented me from eking out the maximum for the paper at hand. I do, however, get the negative right almost every time, and yes, they do print very easily to completely satisfying densities, just as I imagined them when I clicked the shutter. I'm serious. I don't need another paper. The art comes from within and the heart you put into it. I never look to my materials to improve my photography or my prints. I always look to technique and skill and how I can improve. And it works just fine for me. I am often commended for the quality of my prints.

    Quote Originally Posted by clayne View Post
    Thomas, do you not have shots with certain subjects and scenes that have the majority of exposure biased towards shoulder or toe?
    Last edited by Thomas Bertilsson; 03-26-2010 at 08:46 AM. Click to view previous post history.
    "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

  9. #38
    Thomas Bertilsson's Avatar
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    I am glad you have a solution. The finished picture is all that matters in the end. And if you are happy with it, then it's good enough.

    Quote Originally Posted by Willie Jan View Post
    I still have a neg from this situation. So I can do a 6 min test. But going to short get's other problems...
    I mostly do my process of photographing/developing in my standard way. When the light is to bright, i come back another day. When it is to low, also. Adjusting things often make things worse. I am at a point where I am looking at the final print and don't care about the neg anymore. Because my print is what I put on the wall, not a negative. Besides that I use all kind of print papers from cyanotype to baryta and PE.

    Don't loose to much time in getting the absolute perfect neg, because probably it's not printable. A friend of my says that we think that we can create a neg that can be printed without any work, but he says printing is where it starts. Every print needs adjustment to get it even better.
    "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

  10. #39
    Willie Jan's Avatar
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    If I want to use less agitation to keep the highlights from blocking, I will have to develop longer, otherwise the shadow area will be less dense than when it was developed with normal agitation.

    But if I develop longer, the highlights will get more dense also....

    I think the main problem is the combination of them. The first (less agitation) is the solution but the second (longer) ruins your highlights again.

    So eventually you will gain some, but is this worth the efford?
    How much difference is there between the good and the bad.

    Or do we add another variable, dilution. Higher dilution so that the highlight does not get enough fresh developer while the shadow is still working.
    But this can result in streaking with stand development. Maybe first develop in low dilution, andd next in high. Or develop normally and after that put water in the tank so that the developer in the neg is still working until it is used up which would result in the shadow from working longer....
    Wehave so many variables which can be changed and are interacting with each other, that it is complicated to finetune.

  11. #40

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    Quote Originally Posted by Willie Jan View Post
    You are right that 8 stops is printable, but shadows and/or highlights based on your measurements will lose details.
    My basic idea is that i want to see in the photo what i saw at the scene.
    This is only possible when i make studio stillife photos where i can set the light so that it is under 5 stops. This neg can be printed without any problems.
    Of course, not all 10 tonal values will show the same level of detail. The two extreme values (0 & 9) are absolute black or white. Values 1 to 8 show some differentiation and you can spot some detail. Values 2 to 7 definitely show detail/textures. Now that's with only a straight print, without any d&b. Modest burning can reveal some more highlight detail. Mild selenium toning (intensification) can give a better look. IMHO, if you print to get the deepest black without any toning, you'll reach the shoulder of the paper and shadows might be less than ideal. You can print your shadows just a tad lighter and intensify them later with selenium. I feel it gives clearer shadows with more detail, without sacrificing deep blacks. Anyway, the bottomline is I wouldn't expect all the negatives to print themselves automagically. You need to put some effort to get to the best result. Exposing and developing according to the lighting conditions can only get you closer, almost there, not there.

    Finally, I'd agree with Thomas that you don't need to switch from paper to paper. It's good to have some different papers that respond differently in various toners and give warmer/colder tones, but IMHO any good variable contrast paper can give fine results once you know how it behaves.

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