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  1. #1
    Mustafa Umut Sarac's Avatar
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    Secret of 140K MP Daguerrotype

    I read an article http://www.wired.com/magazine/2010/0...type_panorama/ about a newly started to be restored Daguerrotypes at GEH. They report the plates have an sensivity of 140000 Megapixel. They write if images enlarged to 50 meters , it would not lose any detail. Grain size 150 to 800 nanometers.


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    For whom who have no time to check the article , I want to add GEH could not recognize the detail count with loupe or macro lens but stereo microscope. Article puts detailed analysis.
    I want to ask ;
    • Are our films better today ? Can ULF cameras surpass that quality ?
    • What is the particle size of not exposed plate and modern film ?
    • Do we use bromide, chlorine and iodine at our emulsions today ? Who uses them together at their modern films ?

      When Petzval[1][6] lenses were introduced in 1841, with a larger effective aperture and the plate was sensitized not only with iodine but also with bromine and chlorine and forming light sensitive crystals of silver iodide, silver bromide and/or silver chloride that are more light sensitive than silver iodide .

      Exposure times were later reduced by sensitizing the plate with other silver halides: silver bromide and silver chloride, and by replacing the Chevalier lenses with much larger, faster lenses designed by Joseph Petzval.
    • What is the role of Mercury ?

      The image in a daguerreotype is often described as being formed by the amalgam, or alloy, of mercury and silver because mercury vapor from a pool of heated mercury is used to develop the plate; but using the Becquerel process (using a red filter and two-and-a-half stops extra exposure) daguerreotypes can be produced without mercury, and chemical analysis shows that there is no mercury in the final image with the Bequerel process. This leads to questioning the theory that the image is formed of amalgam with mercury development.[11]
    • How some 3D objects looks like jump out of the plate ? Is it because single element
      or petzval lens aberrations or the chemistry or...
      ?


    From wikipedia article !

    The polished silver surface of a daguerreotype gives a feeling of presence where the image appears to be floating in space.How is that ?

    http://en.wikipedia.org/wiki/Daguerreotype

    http://en.wikipedia.org/wiki/Joseph_Petzval

    Thank you,
    Umut
    Last edited by Mustafa Umut Sarac; 01-12-2013 at 01:28 AM. Click to view previous post history.

  2. #2

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    for what it's worth, they show an enlarged clock that is, on the image, 1 mm across -- I've seen much sharper and clearer detail than that on 1 mm of a Minox negative after being blown up to a 4 by 5 print and remember a minox negative is is only 9 by 12 mm, on asa 25 and even 100 film, so I'd say that resolution of the sort they're discussing is certainly possible today, but you have to have perfect conditions. Them saying those images equal 140 gigs today really doesn't mean anything -- people try to compare pixel and grain sizes, but you're talking apples and oranges. Grain is on the microscopic level while pixels are not, so the comparison is only for giggles.

    i don't understand yur last question =-- a 3D microscope will let the observer look at the same spot from two slightly different angles, you won't get real 3-d in looking at a flat image, but you will see the same spot from two slightly different angles and, thus, have a lot more information to make up the final image in your head, which will be clearer than a mere flat image.

    mercury is part of the development process -- i don't remember the chemistry, but don't try it, highly dangerous. Modern deguerrans have other options.



 

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