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  1. #11
    markbarendt's Avatar
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    What did you print that on Athiril?

    You make a great observation about the narrowness of the range in the scene.
    Mark Barendt, Beaverton, OR

    "We do not see things the way they are. We see things the way we are." Anaïs Nin

  2. #12

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    Anthril, can you tell me what you mean by pushing to 51,200 and shooting at 6400?

  3. #13

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    Quote Originally Posted by Joe O'Brien View Post
    Anthril, can you tell me what you mean by pushing to 51,200 and shooting at 6400?
    EI 50,000 means seven stops underexposed with Tri-X. This means (assuming incident exposure, in which a middle tone is placed as a middle tone) anything not at least two steps brighter than a middle tone at the scene of exposure has no chance of even being pushed, no matter what you do; it has fallen entirely below the threshold of sensitivity of the film. The things that are two steps or more brighter than a middle tone can be pushed. Though as mentioned, the things that fell higher than others will be pushed more than those that fell lower.

    Developing for EI 6400 in one way of looking at it means that a tone that fell one step below middle gray upon exposure was pushed four stops up to the edge of high-toned detail and texture with development.

    But, since that it nearly impossible, it probably means using the same developing procedure he uses when he rates the film at EI 6400.

    Stand development adds density to the low tones, but it doesn't increase the film's sensitivity to light. How could it? Developer has nothing to do with a film's threshold of sensitivity to light. That is set by the film's design. Stand development cannot pull texture and detail out of thin air (i.e. from things that fell below the threshold of sensitivity for the film upon exposure). It can help to boost what is there in the lows, in terms of both density and local contrast. But then again, so does a simple push using standard agitation. Stand development might be used in an underexposed situation that was high in contrast, while a simple push might be used in an underexposed situation that was low in contrast.
    2F/2F

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  4. #14
    Athiril's Avatar
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    I pushed to 6400 in development, this was one particular shot on the roll that went out to 51,200, most of the roll was EI 6400, with a couple of extra underexposed shots.

    markbarendt: I didn't bother having someone print it for me.

    Extra development can pull extra detail out. Making the assumption that all developable detail is attained at box speed with N processing is a folly. Then there is the case of how many stops in reflectivity your darkest subject/surface in the scene is below the chosen exposure.


    If I take an example of the top of my head, Kodak 5201 50D, if you know it records 4 stops below the chosen exposure on a straight line before even hitting the toe at the given processing and speed rating. You could spot meter your darkest detail and underexpose that reading for the same ISO (50 in this case) by 4 stops.




    iirc, last time I tested, high pressure sodium street lamps are around ISO 1600, 1/30th-1/60th f/1.4, though citys are brighter than that. So the Rodinal 2 hour semi-stand lets you walk around the city at night hand held and develop the various speeds you'd invariably end up shooting.

    iirc, reciprocity effect at ISO 25,600 will kick in start at 1/60th for Tri-X, so for hand held situations there ended up being little point to it.

  5. #15
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    I find this all very amusing when people start talking about images they shot "at" some ridiculous E.I. It's all very silly, and meaningless. I understand massive underexposure and desperate pushing, but don't try to pretend that you can quantify the actual exposure with an E.I.
    f/22 and be there.

  6. #16
    markbarendt's Avatar
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    Quote Originally Posted by Athiril View Post
    markbarendt: I didn't bother having someone print it for me.
    So, I take it that your example is a negative scan.

    Can we assume also that you tweaked the scanned file a bit electronically to wring out that extra detail?
    Mark Barendt, Beaverton, OR

    "We do not see things the way they are. We see things the way we are." Anaïs Nin

  7. #17
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    This looks good. I have been trying to get exactly look for a few night shots under street lights.

    Did you meter a particular detail with a spot? Or average metering?

    Got a link to more like this?

    MB
    Michael Batchelor
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  8. #18
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    Jerry, I've seen and been told that about the latensification with green light, very dim and very far away. Clair Senft uses it with her Imagelink-HQ and a peroxide latensifier too.

    Nobody has ever told me why it has to be a green light, the peak of human light sensitivity. B&W film is sensitive over a wider range as you know, so why green? TIA
    Murray

    Quote Originally Posted by Gerald C Koch View Post
    There are two ways of increasing the sensitivity of film. There is hypersensitization which is done before and latensification which is done after exposure. According to Glafkides these methods can increase the film speed by 100% t0 300%. However, he goes on to say; "The various methods of intensification are usually critical operations to perform in praactice, since the results will vary not only with the type of emulsion, but also between two identical operations on the same emulsion." I think this sums up why people seldom resort to this type of intensification.

    Probably the easiest method is to hypersensitize the film by exposing it to a dark green safelight. To be effective the light must be of low intensity and long duration. The article I read many years ago described using a Kodak Brownie safelight 7.5 watts with the light output reduced by a half to a quarter at 10 feet. You would have to experiment as to the distance and the time. IIRC, the time was in the range of 10 to 20 minutes. The film must be exposed within a few hours as the effect wears off rapidly.

  9. #19
    E76
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    I wonder how much of a benefit preflashing the film would be in these extreme situations. Eliminating the toe would help with the shadow detail.

  10. #20
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    Quote Originally Posted by BetterSense View Post
    I find this all very amusing when people start talking about images they shot "at" some ridiculous E.I. It's all very silly, and meaningless. I understand massive underexposure and desperate pushing, but don't try to pretend that you can quantify the actual exposure with an E.I.
    I can, it was 7 stops under correct exposure for 400 speed. You can quantify it just like any other exposure, if you cannot quantify that you cannot quantify any exposure at all.
    Last edited by Athiril; 07-05-2011 at 01:57 AM. Click to view previous post history.

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