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56748Magic Lantern and exposure for best dynamic range

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  • Erik Krause
    Jul 8, 2013
    • 0 Attachment
      Hello,

      Magic Lantern team has done it again: Raw histograms, raw zebras, ETTR
      hint and even Auto-ETTR are of the spin-offs of their discovery how to
      access the raw buffers.

      What's it all about? We know that a single raw image contains a
      relatively large dynamic range (11 to 14 EV). In order to make use of
      this dynamic range it is necessary to expose such, that only specular
      reflections and actual lights are clipped in raw. This is a matter of
      trial and error on most cameras, since the histogram is calculated from
      the jpeg data, which clips about 1 or 2 EV levels below the raw data.

      Recent Magic Lantern nightly builds feature raw zebras (colored areas
      where overexposure is to be expected, similar to clip warning in a raw
      converter). The histogram shows how much EV values are still available
      until highlights are clipped. This makes it easy to "expose-to-the-right".
      -> https://en.wikipedia.org/wiki/Exposing_to_the_right
      or (the inventor):
      http://www.luminous-landscape.com/tutorials/expose-right.shtml

      A loadable module even allows for auto-ETTR, which sets exposure values
      on a button press.

      All this is still experimental and works on some EOS cameras only. To
      try you need to install stable Magic Lantern v2.3 first, then get the
      most recent nightly:
      http://www.magiclantern.fm/forum/index.php?topic=3072.0
      (simply unzip and replace the files on your CF or SD card).


      --
      Erik Krause
      http://www.erik-krause.de