Sellective Latent Image Bleaching

Discussion in 'B&W: Film, Paper, Chemistry' started by JackRosa, Dec 10, 2004.

  1. JackRosa

    JackRosa Member

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    I just developed my first negative (after 27 years developing negatives) using selective latent image bleaching. I had tried compensating development, super-dilueted-developer development, staining developers,.... this technique is a winner!
     
  2. roy

    roy Member

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    Hello Jack. For the uninitiated, like me, can you tell my why you adopted this method and what you were trying to achieve. I gather it was successful - how ?
     
  3. Jorge

    Jorge Inactive

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    Roy, this is also known as the Sterry method. David Kachel called it Selective Latent Image Manipulation (SLIMT) and wrote an article in PT many years back. In a nutshell, while bleaching after development increases contrast, bleaching
    before development decreases contrast, and it is a useful technique to have when the contrast range is too big.

    It can be used on paper as well as negatives.

    I preferred to use this on paper when I wanted more "punch" in the print and did not want the shadows blocked up. The problem I have with using this technique with the negatives is that it is not a quantifiable technique. Small variations can make a big difference and the results are not consistent, at least from a sensitometrically point of view.

    What you do is, before you develop the negative or paper, you place it on a very dilute solution of potassium ferricyanide (0.01 to 0.03 %) and then you let it sit in the solution for a little while. What this does is selectively bleach the areas that have more exposure, in the case of negatives, the highlights, in the case of prints the shadows. you then wash it and place it on the developer and continue as normal. Of course all this has to be done in the dark.
     
  4. Bob Carnie

    Bob Carnie Subscriber

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    Jorge

    This method sounds quite interesting, my question to you would be , - Is the pre bleaching affecting the blacks.
    or are you able to hold a believable Dmax with this method???
     
  5. Jorge

    Jorge Inactive

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    Which part are you talking about? pre bleach on the print?. Yes you are able to hold a beleivable black after bleaching on the print, remember you are over exposing the black to the max, with the pre bleaching you "take away" some of that exposure to get separation.

    OTOH remember you dont need to have the maximum Dmax to make it "look" black. In pt/pd the most I have heard people get is 1.5, in my case it is usually in the 1.35 to 1.4 range, yet when you see the prints it looks black...It is all in the tonal relationships.
     
  6. Claire Senft

    Claire Senft Member

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    Use of slective latent image bleaching.

    Prints: You may have a print with the shadows being overly black. This will allow the blacks to be controlled to the depth you desire. You mave have a print that will print satisfactorily on grade 2 but that you wish to have more highlight contrast. You could print the negative on any higher contrast grade paper and thru this technique reduce to blacks to what you had previous obtained. If act you could use grade five paper and have the resulting highlight contrast that is ordinary for grade five paper and the shadows could be bleached back to less than a grade 1. It is a very useful technique for printing.

    Film: You may be taking a photo of a scene that has far more contrast than you wish. If you develop, for example to n-3 you may end up with very muddy tones. Since the bleach affects the greatest density the most you can bring the highlights way down without the muddiness. This technique is also very usable on high contrast films that you wish to use as a continous tone material.
     
  7. dancqu

    dancqu Member

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  8. Bob Carnie

    Bob Carnie Subscriber

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    Jorge

    thankyou
    I was talking about prints,
    I do agree, as long as our eye discerns it as black it works. I am going to try this technique
     
  9. KenM

    KenM Member

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    Here's a link to the article .
     
  10. JackRosa

    JackRosa Member

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    To: Ken

    Ken: Thank you for providing the ling to Ed Buffalos's article on Latent Image Bleaching. By the way, I visited your website and want to congratulate you on your work.

    I noticed <on your site> you indicate that you use HC-110 to develop some of your negatives. I used HC-110, mostly solution B, to develop my 8x10 negatives for a long time with very good results. When I tried Rodinal 1:25 with HP5+ and 1:50 with FP4+ I immediately switched. Another developer that yiedls excellent results is PMK <pyro> 1:2:100.

    Cheers.
     
  11. JackRosa

    JackRosa Member

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    To: Jorge

    Jorge: Thank You for contributing your insight. Gracias por hacer una contribucion de su experiencia.
     
  12. MurrayMinchin

    MurrayMinchin Membership Council Council

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    Here's the article from David Kachel's Front Door...his webzine of old and new magazine articles. As per his request, I'll give the link to his opening page, then hit "Articles", then hit "Zone System Contraction Part III - SLIMT'S".

    http://codemastersworkshop.com/frontdoor/index.htm

    There is some VERY interesting reading there...

    Murray
     
  13. Jorge

    Jorge Inactive

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    Thank you Murray, I often wondered what happen to him. Good to know he is still around.
     
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  15. gainer

    gainer Subscriber

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    Some years ago I tried the SLIMT on prints. It takes considerably more printing exposure and for me it was no different from a method of flashing that I was using. This was what i called "while flashing" and consisted of adding a known amount of non-image light to the projected image. I would set the exposure for the highlight with the flashing light off and then adjust the flashing light to bring the shadow to the desired threshold. This depended on my having an easel densitometer that I could set to read Zones. So, Zone VIII would be set with the enlarger and Zone III with the flashing light.

    As I said, I could not tell th difference between that and a successful application of SLIMT. The SLIMT was not always successful.

    On negatives, the bleaching is easier than latensification as described by Vestal a la Steiner. I was working on a device for latensifying a whole roll of 35 mm without having to sit for half an hour in the dark. Never finished it, though.
     
  16. KenM

    KenM Member

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    Just one more tidbit about SLIMT development: Lynn Radeka uses SLIMT instead of reduced development for all his N-1,2,3 negatives. From reading what he says about it, it's a very reliable method of reducing contrast. About 1/3 stop is lost for every contraction level. Once you've bleached the negatives (and rinsed them in a water bath), you can develop them normally with all other 'N' negatives.

    It sounds simple - I may give it a try.
     
  17. MurrayMinchin

    MurrayMinchin Membership Council Council

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    To avoid confusion, isn't it SLIMT for B&W negatives and the Sterry Method for B&W paper?

    I found SLIMT via Radeka as well. For whatever reason, I had to increase his recommended 8mls of bleach solution to 10mls for SLIMT to give me the right level of contraction. I'll never go back to dilute developer for contractions.

    Murray
     
  18. KenM

    KenM Member

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    I just ran through a few negatives at -1, -2 and -3 using SLIMT - while they're just step wedges, the lower densities look quite strong, so this could very well be a promising way to reduce negative contrast while maintaining shadow separation.

    I used Lynn's recommended dilutions, so I'll see what happens.
     
  19. dancqu

    dancqu Member

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    No more yellow to orange filter for those clouds?
    May make up for the speed hit using the
    latent image bleach. Dan
     
  20. pentaxuser

    pentaxuser Subscriber

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    Murray. Keeps coming up with page not found. No problem with Unblinkingeye article which was referred to in the other thread on dodging and burning for uneven skylines, although not under SLIMT..

    Any help appreciated

    Thanks

    pentaxuser
     
  21. MurrayMinchin

    MurrayMinchin Membership Council Council

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    It did work in 2005 when this thread started...me-thinks Kachel is hibernating, or at least not seeking public attention at this time. I don't know of any other sources for his writing on SLIMT.

    Murray
     
  22. dancqu

    dancqu Member

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    I've just tried finding his 'front door' with no success.
    Within the last year it was on line. His article goes on
    and on and on.

    The article at www.unblinkingeye.com pretty well covers
    the subject. Essentially it is a straight forward very simple
    to execute process. I referred to it as a chemical burning in
    at a previous post. The OP of that thread needed to burn in
    some areas while maintaining good middle and shadow
    area detail.

    The post exposure pre-developer soak in an extremely dilute
    potassium ferricyanide one-shot solution in effect reduces
    exposure in areas of the print which otherwise would be
    a mass of black. So the highlights are burned in at
    at exposure. No additional burning in needed.

    I know, some are thinking it is a chemical dodging because
    the dense areas most reduced. Of course that is where latent
    image bleaching depends. As Mr. Kachel states ferricyanide
    is more active at reducing the more exposed areas, film or
    paper. He goes on and on some more mentioning perhaps
    all the bleaching agents and their way of doing so.

    The use of ferricyanide requires less additional exposure
    than the chemistry used by Sterry who by the way many
    years earlier discovered the phenomena of latent image
    bleaching.

    BTW, his mention is only of graded papers. The method
    should work as well with variable contrast papers. Perhaps
    do without that yellow filter on my lens? The SLIMT also
    works well with film. Dan
     
  23. pentaxuser

    pentaxuser Subscriber

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    Murray and Dan. Thanks. Murray. I should have looked at your post date. I had only just seen this thread, having followed the thread on burning in an even skyline and assumed it was new.

    Dan I could follow the Unblinkingeye article quite well, I think. While it seems to be more targetted to using a high contrast grade to retain punch and still getting shadow detail a la the young lady on beach, my conclusion was that in the case of a featureless sky, you expose for sky detail, getting this right then use the Selective Latent Image Bleaching to restore details to the foreground which otherwise would be very dark and even almost featureless black depending on the difference in the correct exposures for the sky and foreground.

    I suppose that expert dodger/ burners will say that its quicker, less messy, and just as easy to burn/dodge, possibly with flashing as it is to use Selective Latent Image Bleaching.

    El Gringo made a pretty good job of dodge/burn in the gallery for a shot which initially had the typical halo around where rocks met sky. If he reads this thread he may try this method as well.

    I suppose its a question of trying both to see which is easier and/or produces a better print.

    Thanks again

    pentaxuser
     
  24. Bob F.

    Bob F. Member

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  25. pentaxuser

    pentaxuser Subscriber

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  26. MurrayMinchin

    MurrayMinchin Membership Council Council

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    Many thanks from me too :smile:

    That puppy is now forever bookmarked!!

    Murray