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  1. #1

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    Tri-X anomaly in photographing nukes in the 1950's

    I have been working on a project for a few years now in researching atomic testing photography from the 1950s and 1960s. There is a certain type of photography done on a camera called the Rapatronic which was developed by EG&G (Doc Edgerton's company). The Rapatronic took single shots. Two type of rapatronic cameras were developed. The original camera which has a basic exposure of 4µsec photographs the image onto a 3x4 glass plate. The newer Rapatronic (developed in 1956-1957) had a basic exposure of 5µsec and was imaged on 3x4 sheet film.

    On all of the sheet film negatives, there are additional images of what looks like what is called a "corona discharge" or similar to krilian photography around the blast. I believe this is in the UV range and if photographed in color, would be bluish purple. However, this additional imagery shows up only on the sheet film at 5µsec exposure whereas the same image, shot with the same focal length lens, same film type (Tri-X) on glass and NO FILTRATION on either, does not show this anomaly at all. Not even a hint of it.

    Is it possible that the Tri-X sheet film and Tri-X glass plate react to images and spectrum differently, especially in the UV range that would explain why anomaly shows up on one but not the other. Is the difference between a 4µsec and 5µsec exposure that great? Maybe 1/3 of a stop difference? Any thoughts?

  2. #2

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    Is there some wavelength at which the plastic film base might fluoresce but glass doesn't? I can't think of many reasons why plate vs film would behave differently with the same emulsion.

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    That is why my photo of Elvis did not come out right. His Star Power causing a corona discharge. I feel better now.
    I wonder if Tri-X on glass is exactly the same chemistry as on film.

  4. #4
    ic-racer's Avatar
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    Can you post links to the example images? Doc Edgerton did not notice this or comment on it?

  5. #5
    jp498's Avatar
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    Let's see a photo of this kirlian effect on the tri-x sheet film. Lacking that, it could be the film holders picking up some EMP and fogging film if the sheet film used a different film holder material than the plate film?

  6. #6

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    I read that glass optics absorb UV light below about 300 nm whereas the shortest wavelength that can be recorded in a conventional photographic emulsion is about 250 nanometers because the gelatin in the emulsion absorbs any ultraviolet radiation. I also read that a thinner emulsion is more sensitive to UV then a thicker emulsion coating.

  7. #7
    Thomas Bertilsson's Avatar
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    Quote Originally Posted by snapguy View Post
    I wonder if Tri-X on glass is exactly the same chemistry as on film.
    With my limited knowledge that is about all I could possible contribute as well.

    Sounds like an interesting research project.
    "Often moments come looking for us". - Robert Frank

    "Make good art!" - Neil Gaiman

    "...the heart and mind are the true lens of the camera". - Yousuf Karsh

  8. #8
    Mustafa Umut Sarac's Avatar
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    I read last night about a german satellite detector lens. It uses liquid hydrogen and when hit by a tiny intense light , boils and emits image on film. I think fluorescense can be an answer which used at detecting living gems on living tissues with better visibility.
    And I dont think glass plate was tri x ! No reason to hassle at kodak to coat glass with tri x ! I think you can get still coated glass plates today and they are better resolution ones than plastic film. It would have lots of advantage to use old emulsions , check our forums to learn more.
    Can you please ask easier questions ? One Apug members request .

  9. #9

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    Is it possible that at some wavelengths the anti-halation layer is reflective?
    Much glass is opaque to UV, so it is possible that the UV is filtered by the glass, but reflected back to the emulsion by the sheet film?

  10. #10
    NedL's Avatar
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    maybe not uv? How about gamma rays causing cascades of particles within the plastic?

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