Increasing print contrast.

Discussion in 'The Darkroom' started by JamesD, Jun 17, 2006.

  1. JamesD

    JamesD Between darkrooms

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    I've push-processed a roll of ISO 100 film (TMX) three stops to 800 in accordance with Kodak's recommendations. I expected that with a three-stop push, the negatives would be of pretty high contrast, but as-is, printing them at grade-5 on multicontrast paper yields only about average scene contrast. The original scene was fairly contrasty, as well, and the overall effect I was going for was grain and contrast.

    I'm a little disappointed. What I want to do is make the darks darker while not really affecting the lights.

    Is there anything I can change in the print processing to increase the contrast further? I'm already using a #5 filter, and my standard printing process, 90 seconds in Dektol 1:2, 30 in indic. stop, and 3 minutes in the fix. Exposure is 30 seconds at f/8 on the enlarger.
     
  2. Hertz van Rental

    Hertz van Rental TPF Noob!

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    When you push process what you are in effect doing is under-exposing the film and then attempting to compensate by over-development.
    This gives:
    High highlight contrast.
    Low shadow contrast.
    High average density.
    High fog level density.
    The last three tend to offset the first one so while you do get some overall contrast increase it is not as much as you would think.
    If you are already printing with a 5 and Dektol 1:2 and not getting a contrasty print then there are a few things I would check.
    It is possible that you have slightly under-developed the neg so it is a little thin (this would print flat and require printing through a high contrast filter to get 'normal' results).
    The other thing is to check print dev temperature.
    If the temperature drops below about 17C then the component that produces the blacks stops working and you get grey, washed-out prints. A water bath is essential (print dev having a large surface area in the tray loses heat rapidly and can quickly drop below the optimum temperature).

    It is possible to increase the contrast and density of a neg after development - but it is not something that should be approached lightly as the chemicals used are usually very toxic and neg permanence is often compromised. In effect - the neg will not last very long (only years, not 100's).
    The simplest method is to tone the neg. Sulphide toning works the best. Paper is less sensitive to amber light so staining the silver brown has the effect of increasing contrast when it is printed.
    Sulphide tone the neg the same way you would a print.
    The other option is to use an intensifier. You basically bleach and re-develop the neg to push up contrast.
    The standard intensifiers use Chromium, Uranium and Mercury - and because of toxicity and lack of popularity are not easy to find.
    I wouldn't recommend this course of action.

    A better solution would be to get some lith film, make a positive and use that to make another neg. Using lith developer would just give you black and white (no greys). You can process it using standard developers to control the contrast.
    The final option is to get hold of some lith paper and print onto that. Again, choice of developer affects the final contrast.
     
  3. Philip Weir

    Philip Weir TPF Noob!

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    Hi, you are using the wrong film to start with, TMX 100 is a very fine grain film. Maybe start with a 400 Tri-X film, which is pretty grainy to start with, then using your original process, you should bump up the grain. I personally shoot fine grain then use a very old Mezzo screen and print with it on top of the paper. This is a bit tricky, but required effect is done by printing part exposure with screen, then removing screen for the remainder of exposure. Trial and error method. "Hertz Van Rental" posted some good advice. You could also use straight print developer, and don't be too concerned about over developing the print, within reason of course.

    www.philipweirphotography.com
     
  4. JamesD

    JamesD Between darkrooms

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    As usual, Hertz, you've clarified my thinking. Reexamining the print, I realize that you're right, the highlight contrast is good, but the shadow contrast is iffy. Also, there does seem to be a bit of fog, although I've very little experience with fog (either I'm lucky, or I've managed to avoid it so far) so I'm not entirely certain.

    The basic problem I'm having is that I want the shadows darker, but I'm already using a #5 contrast filter, and the highlights are starting to fill in by the time the shadows reach the about half the density I want. My dev temp is right around 24C, which I understand is the maximum allowable temp?

    I'm not interested in toning the negative, as I'm already pushing my luck with ordinary BW chemistry. The toxicity is unacceptable where I live. The idea of using heavy-metal intensifiers (Uranium?! I don't think so!) in this setting just isn't agreeable.

    As it happens, I do have some Arista Lith film, in 4X5 sheet size, about 25 sheets, along with a ton of developer for it. It was given to me by Ed, with the suggestion that I play with it and see what I get. He included two packets each of Part A and Part B of the developer, which is way more than I need, of course. I don't know how old the film is, and it hasn't been in cold storage, so I have no idea what sort of condition it's in. You're saying that if I persue that course of action, I should develop it in normal developer? At this point, I have on hand TMax, D-76, and Dektol developers. Also, are you suggesting that I make a contact exposure onto the lith film, or expose with the enlarger? I'm rather limited in my options when it comes to enlarging anything other than 35mm format, as my enlarger handles only 35mm negatives.

    Phillip, the grain with the 100TMX +3 stops is fine, and more or less exactly what I was looking for, but I didn't expect the iffy shadow contrast. It was more or less an experiment, but there are a couple of shots on the film that I do wish to use, so I'm looking now for a way to make it work. You suggest overdeveloping the print, do you mean with normal print exposure, or altered exposure? I suppose that extra agitation would help with the contrast, correct? What about less dilution?

    P.S., Nice work on your website. I love the stopwatches!
     
  5. Hertz van Rental

    Hertz van Rental TPF Noob!

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    The lith film will probably be OK to use.
    You can either contact print the neg onto the lith or enlarge it onto the lith.
    Taking the second course allows you to choose segments and it will also magnify the grain.
    Trim the lith down to fit the film carrier.
    Developing in lith dev will just give black and white - no greys.
    The threshold point for black to white is determined by exposure and development. Not as difficult as it sounds as lith is insensitive to red safelight so you can develop by inspection.
    The same applies to processing in normal dev. D-76 is a good one to start with.
    Exposure, development and dev concentration (and type to an extent) will effect how much tonal range you get in the neg. But in the normal course of events you won't see much difference - you'll just get some.

    Overdevelopment of the print doesn't really happen.
    Photo paper is designed to process to Dmax in the blacks, so you can't develop beyond that. And you get little or no change in the whites and greys unless you have over-exposed to begin with.
    24C seems a little high. It won't have much effect on the print other than getting the image to appear quicker, though.
     

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