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  1. #1
    MattKing's Avatar
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    Comparing Spectral Sensitivities

    As a result of a fairly spirited discussion yesterday I've been thinking about spectral sensitivity.

    In particular, I've been thinking about how the spectral sensitivities compare between human vision, black and white film and various types (Selenium, CDs, Silicon, Gallium etc.) of exposure meters.

    Can someone here provide a reference that would include some comparisons (ideally in graphical form) that would show the similarities and differences?

    I'd like to be able to take better account of the differences when I am using exposure meters - particularly considering the fact that I have and use a variety of different exposure meters.
    Matt

    “Photography is a complex and fluid medium, and its many factors are not applied in simple sequence. Rather, the process may be likened to the art of the juggler in keeping many balls in the air at one time!”

    Ansel Adams, from the introduction to The Negative - The New Ansel Adams Photography Series / Book 2

  2. #2
    MattKing's Avatar
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    Anyone?
    Matt

    “Photography is a complex and fluid medium, and its many factors are not applied in simple sequence. Rather, the process may be likened to the art of the juggler in keeping many balls in the air at one time!”

    Ansel Adams, from the introduction to The Negative - The New Ansel Adams Photography Series / Book 2

  3. #3
    benjiboy's Avatar
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    I don't know how you would compensate when using different exposure meters Matt, or indeed what practical use this would be when shooting monochrome film, but here you are http://photo.net/learn/optics/edscott/pss00020.htm


    best wishes
    Ben.
    Last edited by benjiboy; 08-26-2012 at 01:41 PM. Click to view previous post history.
    Ben

  4. #4
    Photo Engineer's Avatar
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    Try this for the eye: http://en.wikipedia.org/wiki/Color_vision

    Film sensitivities are attached.

    PE
    Attached Thumbnails Attached Thumbnails dye types.jpg  

  5. #5
    Bill Burk's Avatar
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    Hi Matt,

    I consider all this out-of-date. They don't include the latest cells. They don't include the lastest films.

    But Todd-Zakia show all that you ask...







    I am intrigued by this too, but worry that it will drive me insane to try to correlate all this in the field.

    For example, I was surprised that shots from a few weeks ago on TMY-2 gave me realistic skies without a yellow filter. I didn't even see the clouds the film picked up. Thought for sure the skies would be blown out. So my eyes don't match the film.

    I know from a test of an hour-long exposure to near-infrared that TMY-2 is fairly blind to deep red. I also know that my light meter responds to the same near-infrared so I already know the meter doesn't match my film's response.

  6. #6
    MattKing's Avatar
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    Thank you all.

    This helps me deal with the situations at the relevant ends of the spectrum - at least as far as choosing which meter to use in which (relatively extreme) situation.

    Any further thoughts about where I could enquire about spectral sensitivity of a silicon blue cell ("SBC") photo diode?
    Last edited by MattKing; 08-26-2012 at 02:54 PM. Click to view previous post history.
    Matt

    “Photography is a complex and fluid medium, and its many factors are not applied in simple sequence. Rather, the process may be likened to the art of the juggler in keeping many balls in the air at one time!”

    Ansel Adams, from the introduction to The Negative - The New Ansel Adams Photography Series / Book 2

  7. #7
    benjiboy's Avatar
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    Quote Originally Posted by MattKing View Post
    Thank you all.

    This helps me deal with the situations at the relevant ends of the spectrum - at least as far as choosing which meter to use in which (relatively extreme) situation.

    Any further thoughts about where I could enquire about spectral senitivity of a silicon blue cell ("SBC") photo diode?
    Selenium cells have the widest spectral sensitivity that is closest to that of film, but I suggest you contact Gossen about S.B.C cells.
    Last edited by benjiboy; 08-26-2012 at 02:47 PM. Click to view previous post history.
    Ben

  8. #8
    Leigh B's Avatar
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    Quote Originally Posted by MattKing View Post
    I've been thinking about how the spectral sensitivities compare between human vision, black and white film and various types (Selenium, CDs, Silicon, Gallium etc.) of exposure meters.
    The only comparisons that are meaningful are between the film sensitivity curves and those of various exposure meters.

    While the meter sensor technology has a major impact on its spectral sensitivity, it does not define same.
    Meter manufacturers incorporate filters to modify the sensor response, in an attempt to duplicate that of film.

    For a meaningful analysis you need to obtain the sensitivity curves for the actual meters (make and model) of interest,
    and compare those with the curves for the actual films.

    - Leigh
    “Wise men talk because they have something to say; fools, because they have to say something.” - Plato

  9. #9

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    You're right Leigh! The problem is that while I can obtain spectral response charts of most film online but not so with meters. Almost no meter manufacturer published spectral response of their meters.

  10. #10
    Leigh B's Avatar
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    I cannot dispute your statement. I know I have seen spectral response curves for meters in the past,
    but I don't know how commonly they are available or from which manufacturer(s).

    Good luck in your quest.

    - Leigh
    “Wise men talk because they have something to say; fools, because they have to say something.” - Plato

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