Exposure / snow

Discussion in '35mm Cameras' started by Alan Browne, Oct 7, 2003.

  1. Alan Browne

    Alan Browne Guest

    When shooting snow scenes in bright sunlight, shaddows on the snow are
    usually blue in color. I assume that is the sky color.

    I also assume that underexposed white areas will appear grey, not blue.

    Is this correct? Other comments?

    Thanks,
    Alan.
     
    Alan Browne, Oct 7, 2003
    #1
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  2. I know that most camera meters get fooled by bright snow lighting. Hence
    they tend to underexpose the scene, which "I think" gives the snow a blue
    cast.

    That's why it's recommended to overexpose snow scenes by couple of stops.

    Elie
     
    Elie A Shammas, Oct 7, 2003
    #2
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  3. It is.
    Only blue areas can appear blue when underexposed. So yes.
    On the other hand, overexposed blue areas can indeed appear white.
     
    Q.G. de Bakker, Oct 7, 2003
    #3
  4. I would assume that the shadows are blue because all the light in them is
    scattered, and none of it is direct, and atmosphericly scattered light has a
    lot of blue in it. (I'm not sure why)
     
    William Graham, Oct 8, 2003
    #4
  5. That's correct. The clear blue sky has a color temperature of about 10000 Kelvin.
     
    Michael Scarpitti, Oct 8, 2003
    #5
  6. Alan Browne

    brougham3 Guest

    Yes. But not because it's reflecting the sky. Light that is scattered
    tends to lose the red part of the spectrum. So when we look up and see
    scattered light, we see more blue. When we look at the shadowed area, we
    see more blue.

    Really look hard and pay attention to what the actual colors you see are.
    You can learn to see what color the light is. Our brains "know" that snow
    is white, so in the morning, when the dawn's light casts a pink hue on the
    snow, we see it as more white than pink. In shadows at midday, we "know"
    the snow is white, so we tend to overlook the blue hues. But if you look
    carefully, you can see these color casts.
     
    brougham3, Oct 8, 2003
    #6
  7. Alan Browne

    Alan Browne Guest

    Thanks, I'm very aware of how bad humans are at color perception, myself
    included. I am more concerned with the appearance of blue v. grey in
    slides due to underexposure.

    Alan.
     
    Alan Browne, Oct 8, 2003
    #7
  8. Alan Browne

    Peter Chant Guest

    Is the trickier issue, if the shadow areas really are so blue why don't
    we notice it with our eyes?
     
    Peter Chant, Oct 8, 2003
    #8
  9. Alan Browne

    Alan Browne Guest

    You do when you "look", on the other hand on a really bright day the
    contrast is very, very high and your eyes can easilly be dazzled by the
    light... Shaddows look like, well, shaddows... we don't assign a color
    to them we assign the label "shaddow".
     
    Alan Browne, Oct 9, 2003
    #9
  10. Alan Browne

    brougham3 Guest

    When you underexpose blue, you get darker blue up to a point where it
    becomes indistinguishable from a shade of gray.
     
    brougham3, Oct 9, 2003
    #10
  11. Yes.....Also, our eyes are good at relative colors, but not too good at
    measuring color balance without having anything to compare it with.....For
    this you need special light meters that they use in television that are
    capable of reading the percentage of the three primary colors in any light
    source.
     
    William Graham, Oct 9, 2003
    #11
  12. Alan Browne

    Deathwalker Guest

    Lets see. meter thinks its very bright (which it is) and stops down. take
    a spot meter reading from dark shadow areas in picture may help. Or carry
    one of those grey cards and place in front of you and spot meter off that.

    Under exposed trannies are dark (dense.) over exposed are thin and details
    lost. Scanning and printing i would favour under exposure for trannies.
     
    Deathwalker, Oct 11, 2003
    #12
  13. Alan Browne

    Dave Scott Guest

    I have found that using a UV filter helps with preventing the blue. Also
    using a polarizing filter would help do the same.
     
    Dave Scott, Oct 13, 2003
    #13
  14. Alan Browne

    Alan Browne Guest


    ...if blue is the natural color of the shaddow area, then I would prefer
    to capture it as blue...
     
    Alan Browne, Oct 13, 2003
    #14
  15. But your eyes don't 'see' it as blue. Also the film records it as
    bluer than it should, so some SOME reduction is in order.
     
    Michael Scarpitti, Oct 13, 2003
    #15
  16. Some reduction then should be partial, only in the shadows. Hard to do using
    filters.
     
    Q.G. de Bakker, Oct 13, 2003
    #16
  17. The effect of the filter on sunlit part won't be as noticable because
    of its greater luminosity. The 'skylight' filter is often all one
    needs, though some people use a stronger one, such as an 81 B or C.
     
    Michael Scarpitti, Oct 14, 2003
    #17
  18. Also, our eyes are more responsive to some colours than others. Maximum
    response is to orange wavelengths (roughly the same as UK streetlights
    give out) and minimum is to blues (which makes you wonder why that
    colour was chosen for UK emergency service vehicle lights).
     
    Andrew Eremin, Oct 15, 2003
    #18
  19. Alan Browne

    Peter Chant Guest

    Because blue is a colour that men understand. Flashing peach or
    aquamarine lights would just be far to difficult to understand.
     
    Peter Chant, Oct 15, 2003
    #19
  20. Alan Browne

    Rudy Garcia Guest

    It is because the light is preferentially scattered by the molecules in
    the air.

    Your eyes are coupled to a wonderful processor, called a brain, which
    makes you "see" what you expect to see. It knows that snow is supposed
    to be white so it performs an on-the-fly white balancing to make the
    snow look white to you.

     
    Rudy Garcia, Oct 16, 2003
    #20
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