wetplate and uv sensitivity

Discussion in 'Miscellaneous Equipment' started by johnielvis, Dec 20, 2012.

  1. johnielvis

    johnielvis Member

    May 21, 2010
    Medium Format
    General knowledge seems to say that wetplate/collodion is very sensitive to UV light and not to visible light.

    However, I see very sharp wetplate photographs done with very fast lenses. These lenses are apparentlhy not corrected to focus uv light at the same plane as visible light.

    My question: why are the wetplates not blurred from being out of focus due to the uv focus shift?

    The sharpness is leading me to believe that wetplate is not so sensitive to UV as it is much much more to blue and blue only.

    My experience is only in dryfilm/cogeletain, no wetplate/collodion, so please enlighten me as to what is REALLY going on here.
  2. jon koss

    jon koss Subscriber

    Sep 4, 2004
    Boston, MA
    Here is a tidy little graphic from lundphotographics.com. I can't attest to the correctness of the sensitivity info, but if it is correct then the collodion is sensitive to blue and blue/violet with diminishing sensitivity towards the infrared and ultraviolet ends of the spectrum. True UV begins around 400 +/-, so the collodion does not look fabulously sensitive to UV light. The glass of the lens itself may absorb a bunch of UV as well, which would make it even less of a factor. I am not a wetplate practitioner so don't take this as gospel.



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