Odd question but hey im curious... regarding d65

Discussion in 'Archived Threads 2001-2004' started by John-Miles, Nov 19, 2002.

  1. John-Miles

    John-Miles Screenwriter

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    When people refer to d65 I assume they mean the color temperature of 6500 Kelvin. now my question is this, id that 6500k refering to the Planck Distribution for energy density of radiation per unit volume per unit wavelength at specific temperatures?
    If it is then that leads me to another question, why is 6500 the standard? as far as i know illumination form the sun which i would assume to be ideal if only at about 5800 kelvin.
    anyway i know this is kinda technical but if anyone knows id love to hear what you have to say [​IMG]
     
  2. John-Miles

    John-Miles Screenwriter

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    no insight from the Guru's of the forum?
     
  3. Scott Barnhart

    Scott Barnhart Stunt Coordinator

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    Well, I am by no means a guru, and everything I know about this I learned from Google in the last 20 minutes! [​IMG]
    In any case, you seem to be correct on your first question re: "Is 6500K referring to Planck Distribution?"
    A quick search of google for "planck 6500 ntsc" brought up several hits including this article which gave some good insight and taught me a lot.
    Then a search of "black body radiation 6500" brought up this article. Search down to the section "Colour Temperature" where you read this paragraph:
     
  4. John-Miles

    John-Miles Screenwriter

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    Ah ic ic ic, i never considered the refraction and ambient conditions...... yes now it makes perfect sense.
    reviewing the graphs from those links you provided scott shows something else interesting 6500k would emphasize greens more than anythign else, maybe thats why most dont find green push to be objectionable, its actually a natural phenomen.
    thanks for the infor Scott.... I should ahve taken that initative myself... [​IMG]
    you know its amazing the stuff you can learn while sitting in a classroom... thats where this question came form [​IMG]
     
  5. Gregg Loewen

    Gregg Loewen Video Standards Instructor, THX Ltd.
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    6500K D was chosen as the NTSC standard back in 1953.
    There are some bodies (mainly Japanese) that are now lpushing for a new standard of 9500 K. They think that a picture with more blue looks better.

    Regardless, you want to have color temperature match what ever standard the master was telecined at.

    Regards
     
  6. John-Miles

    John-Miles Screenwriter

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    hmmmm ah yes there is that as well you do have to match the master recording dont you?

    you know its funny but its these threads that i enjoy the most sometimes around here.

    I assume the standard for HDTV is also 6500 kelvin?
     

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