Quick Question About Inter-Negative Printing

Discussion in 'Contact Printing' started by Fragomeni, Feb 4, 2011.

  1. Fragomeni

    Fragomeni Member

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    Hi all. This is fairly specific to paper as I'm working with printing from paper negatives but I think the information should be valid regardless of negative material. If have a positive (actually inter-positive), in some cases an positive enlargement from a film neg or a positive contact print from a film or paper neg), and I want to contact print an inter-negative from this positive, how do I determine the proper time and filter grade to properly render the positive information in the inter-negative so that it can properly contact printed to produce a final positive?

    What gets me is that I can't quite look at a negative image and determine if it will produce the positive the way I intend so I'm looking for a workflow that will help me know how to get the inter-negative where it needs to be to properly print the final print. Thanks for the help!
     
  2. David William White

    David William White Member

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    One way to do this is to use a step wedge (purchased, or make one yourself) and place it between two sheets of paper, based on the premise that the step wedge will replicate the density of a paper negative. More directly, you could also make yourself a step wedge on paper ie. say 21 steps from 0 to 1 in 5% steps.

    Do test strips for time and filtration until the step wedge nicely reverses and each step is discernable, then record aperture, height, time, etc. You are right -- this will need to be found for your paper, your lamp, and your chemistry.
     
  3. Fragomeni

    Fragomeni Member

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    Excellent, thats what I was thinking. I guess I had a lack of confidence in my knowledge. How does the following sound? If I print a step wedge on the inter-positive and note the last step that shows density before going to paper white, then when I print the inter-negative the step wedge should reverse and when that step (the one right before paper white on the positive) prints as the step before the blacks block up to full black then the image should be properly reversed. Does this sound like an accurate way to approach it?
     
  4. Fragomeni

    Fragomeni Member

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    I guess more simply: print a step wedge and pick a landmark on the wedge, then reverse the wedge so that the chosen landmark prints as the reciprocal value i.e. paper white prints as full black OR the last step showing density before paper white prints to the last step showing separation before full black. Right?
     
  5. David William White

    David William White Member

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    You got it. I usually start with a determination of time-to-maximum black, then divide up evenly, but same difference. Basically, you are making an artificial, ideal interpositive.

    Find time for filters from 00 to 4 (or whatever) so you have those as reference when you need them.

    I've only ever done 9 steps as that is sufficient for my temperment, but from your previous posts, you sound like a stickler...:D
     
  6. Fragomeni

    Fragomeni Member

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    Thanks David, I appreciate the help! And yea, I tend to get a little obsessive with being as precise as possible :blink:
     
  7. greybeard

    greybeard Member

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    I guess more simply: print a step wedge and pick a landmark on the wedge, then reverse the wedge so that the chosen landmark prints as the reciprocal value i.e. paper white prints as full black OR the last step showing density before paper white prints to the last step showing separation before full black. Right?

    If I understand your original question correctly, you will want to match both the dark and light ends of the scale, not just the dark one. The major difficulty in making copy prints (positive/negative/positive) is in controlling not the density but the contrast. It is very easy to get excessive contrast from printing paper, which is one reason why in-camera paper negatives are often pre-flashed.

    It seems that you would want to print a step wedge and adjust both the exposure and processing until the last step before maximum black, and the last one before paper base white, have their reciprocal values after the reversal. The steps in between may not be linearly related to the corresponding densities on the original, so there may be some tweaking required for "best" appearance, but at least you will be starting with a full-range image.
     
  8. David William White

    David William White Member

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    Good points and clarification. And making the step wedge will tell you how much preflash is required by your paper.
     
  9. Fragomeni

    Fragomeni Member

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    Dealing with contrast isn't much of an issue. Contrast is easily controlled by either paper grades or contrast filters. As to the step wedge, all you have to worry about is printing the reciprocal of one step on the wedge. The wedge, whether 21 or 31 steps, is designed to record tone in 1/2 or 1/3 stop increments. Those measures are fixed. Choosing one step on the wedge and printing its reciprocal will render all other steps printed to their reciprocals equally. The only remaining issue is contrast as you described and that can be managed through the use of filters or paper grades.
     
  10. Fragomeni

    Fragomeni Member

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    Measures like these and others that people take to combat the challenges of paper negs escape me sometimes. Paper negatives have been used successfully since the beginning of photography and it was never as complicated as people make it out to be (myself included). I've never found pre-flashing to be useful or serve any real purpose. Paper is orthochromatic, treat it as such and use the methods devised 150 years ago to efficiently capture an image on this type of material and it should work in the same ways it always has.
     
  11. David William White

    David William White Member

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    That may depend on the illumination in the scene as well as the final look. I preflash in batches after I cut my paper to size but still need to use a lens filter if I'm shooting outdoors in clear sunny light.

    Also worth mentioning if things get rough is bleaching before developing the paper negative, i.e. bleaching the latent image. I've only done it to see if it works, but it's not something I can do consistently.
     
  12. David William White

    David William White Member

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    POP paper, slower emulsions,less aggressive developers, etc. etc.

    Preflashing does reduce the contrast as well as increases the effective speed of the paper.

     
  13. Fragomeni

    Fragomeni Member

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    I'm talking about simply printing for reversal here, excluding if you do anything extra to the image after the latent image has been recorded that would cause tones to diverge in some way or another. A stop is a stop is a stop. Thats why a step tablet serves a purpose. If you could take say steps 12 and 15 on a 31-step tablet and print it in such as way that step 12 somehow reads as step 11 and step 15 somehow reads as step 19 (obviously without interfering in the exposure in some way), well then you'd be in a pickle and the step tablet would all of a sudden no longer be a constant from which we can gauge exposure. Stops are described logarithmically and we do this to accurately represent differences. There is no compressing or expanding defined differences in tone otherwise they could not be represented logarithmically.
     
  14. Fragomeni

    Fragomeni Member

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    Yea I acknowledge these things to have their own effects but overall I haven't found many to be of use (but thats just me, I am no litmus test!)