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Thread: latensification

  1. #11

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    Perborate Vs light latensification

    Sodium erborate is much easier to use. Pretty fool proff adds about a stop to most films. Load your M6 or M7 put on your prettiest black Summilux. Go out and shoot a roll using two frames per subject...one at your normal speed and one at twice your normal speed and run it thru the prebath. Are the negatives that received half as much exposure, properly exposed? Is the shadow detail in the film that was normally exposed richer than normal. It works with any range of exposure and it is pretty fool proof...it either works or does not.

    Low level light intensification takes greater testing to find the proper amount and duration of light. It requires a really darkroom not a semi darkroom. Patience to wait until the 15 plus minutes have passed is required. It does not work well with exposures of say 45 seconds. Probably work work well with exposures of 1/100.000th of a second either. Where it is usable it can add as much as two stops of sensitivity. Once tested and set up it is easier than dropping a Hassleblad...lot less expensive too.

    I am too deaf to much care about Kareoka, and I am a recovering alcoholic but Helen, dear lady, tell me more about the popcorn at that tavern...is the atmosphere free pf pickled pigsfeet?...Love your photos dear.

  2. #12
    Helen B's Avatar
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    'Go out and shoot a roll...' thanks to you for the inspiration, I was going to shoot a few rolls. Anything that would need a real dark darkroom would be out of the question for me, so perborate is the thing. I might even find another use for all that peroxide. Can one be a perborate blonde? I need a new 'do' for the NYC Night of a Thousand Gowns in a couple of months. Which reminds me, I should try to get last year's snaps to them before this year's event. A year is such a tight deadline to meet.

    'Once tested and set up it is easier than dropping a Hassleblad...'
    Have you determined that by a repeatable experiment, or is it just supposition?

    ...is the atmosphere free of pickled pigsfeet?'
    Not when I'm there. I wonder if that is just a coincidence or should I change my perfume? Or my socks?

    Thanks very much for the kind comment on my snaps. I'd love to see some of yours.

    Best,
    Helen

  3. #13
    Cheryl Jacobs's Avatar
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    I hate being ADD. I can't get past the first five sentences of the first post..... I just glaze over......

  4. #14

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    once was enough

    I did not have to do the experiment with a Hasselblad a second time. I was convinced without having to do it 24 more times to achieve a high statistical probability...my apologies to Deming and Taguchi. Helen I am willing to bet that perborate, if you wished, could make you the fastest blond in either NYC or Lonum town but I conjecture that you could never be overexposed. My faith in you is so complete that should I be able to borrow $.25 from my spouse I would bet it all on you. Alas, I have insufficient collateral to establish a line of credit exceeding a nickle with anyone that knows me.

    Cherly do worry about it just keep using that Bronica so well.

  5. #15

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    Quote Originally Posted by Claire Senft
    It will also add a bit to film base fog.
    Fb+f, somewhere around 0.10 or a little more in density? I seem
    to recall having read of a post-exposure technique applied to an
    entire roll of film; very similar to what you describe. I recall
    nothing about such long exposures.

    Off hand I'd think the result would be the same, pre or post
    exposure; pre-expose then shoot or shoot then post-expose.

  6. #16
    Helen B's Avatar
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    I wonder if the difference is something like this (in a very simplistic manner):

    The post exposure occurs at such a low intensity that it would be unable to cause much fog: the rate of creation of silver atoms is too low for them to be stable unless there is a latent sub-image centre (with two atoms, so more stable than a single atom, but probably undevelopable) to join onto and thus become stable. Therefore post exposure low intensity light is able to add atoms to fairly stable sub-image centres and turn them into developable image centres.

    Now that's probably not the real truth. I think that it is way more complicated than that so just look on it as a diagram, as an architect might say.

    Pre exposure flashing, at least the version that I'm aware of, works in a different way, at a higher intensity.

    How does that sound? It might all be nonsense - it's late and I'm weary.

    Best,
    Helen

  7. #17
    fhovie's Avatar
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    I will try the perborate! - I don't understand the difference in results between the latensification listed above and simply preflashing.

    I really love apug .... where else would you learn all this stuff!!!

  8. #18
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    Um...excuse me Claire, Helen & Cheryl...got a kick out of your banter back and forth!

    I think I'm following you regarding the "awakenings" of silver crystals that had received just below the number of photons needed to become "viable", and therefore unable to be developed into usable shadow texture. If I'm wrapping my head around this properly, wouldn't this work in any development situation ( -1, -2, +1, etc)? Wouldn't it only ever effect the lowest tones?

    As an alternative couldn't you instead give -1 SLIMT (David Kachel's method) and +1 development & get the same effect without being subjected to complete darkness for 15 minutes? (Although this might only work for Normal development?)

    Interesting for sure!

    Murray

  9. #19

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    ANY n LEVEL

    Once you have established a suitable normal condition of time and intensity for a film at an elevated speed due to latensification with light you can work out N+ and N- conditions. However, since you are increasing film base fog very extended development will also raise fog levels here as extended development does without latensification. In other words additional testing of the latensification and subsequent modification may be in order so that you do not get grossly inflated fog levels. N- should not be as much of a concern.

    With the perborate I would not worry about using it effectively with N+ and N- times. If a film that you have used will give you the following without perborate are for example n-2= 40, n=64, n+2=100 and you find for a normal ...N... condition with perborate you get 125 film speed then your N-2 should be 80 and you N+2 should be 200. Should work very nicely. Not all films are going to give you exactly 1 stop increase. I do not use a wide variety of films. I buy Tech Pan...at least until now and 100TMax in 100 foot rolls. Although I have a nice 6x7 camera with 4 lenses I work almost exclusely in 35mm.

    This is a suggesstion for those that use 35mm and want to work with the zone system or BTZS techniques in 35mm...it is what I do. Buy your film in bulk. A 100 foot roll is the equivalent of 18 36exposure rolls. I but 100TMax from B&H...the imported version.. for about $27.00 including freight to Milwaukee. I load 6 exposure rolls..enough for 6 exp+leader. I set up my tripod and make 4 identical exposures with ..or without a particular filter and then 1 exposure with a filter that seems to have possibilities and 1 exposure that seem not likely to be useful. If the first 4 exposures were with a filter then 1 of these last 2 will be without a filter. By taking for indentical exposures I have protected myself from negative damage. And I have developed real life experience in finding proper filter factors for my film and conditions I use it under. Having done the foregoing I develop my film for the subject brightness range that existed at the scene I do not know if I am a meticulous person. I am more likely tedious. As a child I was always instructed "If a thing is worth doing, it is worth doing well". I fear that I have corrupted this into "If you are going to do something, be sure you make a big production out of it."

  10. #20
    Ole
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    Quote Originally Posted by Claire Senft
    For high contrast situations that have light sources in them a developer that uses pyrocatchin is very likely to be unbeatable making the bright areas more printable. Ansel Adams has a good illustration of this in his book "The Negative".
    Off topic here, but that developer was Windish' Compensating Pyrocatechin. There is an even better illustration in "Die neue Foto-Schule" - by Hans Windisch. I have tried it on negatives from a solar eclipse, and it really does deliver details both in the shadows and highlights - even when the highlight details were sunspots!
    -- Ole Tjugen, Luddite Elitist
    Norway

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