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Exposure/HDR tab questions

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  • John Riley
    Some of the recent changes to PTGui pulled a pano out of the fire for me: I had mistakenly left the camera on auto exposure (aperture priority) on a pano! It
    Message 1 of 2 , Jan 6, 2008
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      Some of the recent changes to PTGui pulled a pano out of the fire for
      me: I had mistakenly left the camera on auto exposure (aperture
      priority) on a pano! It took a while for me to actually realize that
      that was the problem. So, this was the first time I delved into the
      Exposure correction/ Vignetting correction portions of the Exposure/
      HDR tab.

      I wondered if there was any interplay between the Exposure correction
      checkbox and the Automatic exposure and color adjustment
      optimization. Maybe I am crazy, but it seemed like I got different
      results if I (1) just clicked the Exposure correction box versus (2)
      clicking "optimize now", clicking the Exposure correction box, then
      clicking the "reset" button. In other words, would the result of
      clicking the Exposure correction box be different depending on
      whether the "optimize" button had been clicked? Usually I was only
      optimizing vignetting, but I did try some fine tuning of exposure.

      John

      John Riley
      johnriley@...
      jriley@...






      [Non-text portions of this message have been removed]
    • Joost Nieuwenhuijse
      Hi John, It may become clear if you take a look at the Image Parameters tab. You ll see two fields: EV and Exposure Offset. The Exposure Offset field is user
      Message 2 of 2 , Jan 6, 2008
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        Hi John,

        It may become clear if you take a look at the Image Parameters tab.
        You'll see two fields: EV and Exposure Offset.

        The Exposure Offset field is user editable and always affects the
        brightness of the result, regardless of whether the Exposure correction
        checkbox is checked or not.

        EV is a read only field, calculated from the EXIF parameters (ISO,
        Aperture and Exposure Time). If Exposure Correction checkbox is checked,
        the images are also brightness corrected according to the EV value. If
        the checkbox is not checked, only the Exposure Offset field is used.

        If you enable Exposure Optimization in the Settings dialog, the Exposure
        Offset field is optimized. For example, if your image has a +2EV
        Exposure Value, and the optimizer finds that it actually is +2.1EV, then
        the Exposure Offset is set to 0.1. In general with digital cameras
        there's no need to optimize exposure, since the EXIF values should be
        accurate enough. It's useful mainly for scanned film.

        So in general you can leave the settings to 'only if necessary' and
        enable the Exposure Correction checkbox if you used auto exposure and
        would like to correct that.

        Joost




        John Riley wrote:
        > Some of the recent changes to PTGui pulled a pano out of the fire for
        > me: I had mistakenly left the camera on auto exposure (aperture
        > priority) on a pano! It took a while for me to actually realize that
        > that was the problem. So, this was the first time I delved into the
        > Exposure correction/ Vignetting correction portions of the Exposure/
        > HDR tab.
        >
        > I wondered if there was any interplay between the Exposure correction
        > checkbox and the Automatic exposure and color adjustment
        > optimization. Maybe I am crazy, but it seemed like I got different
        > results if I (1) just clicked the Exposure correction box versus (2)
        > clicking "optimize now", clicking the Exposure correction box, then
        > clicking the "reset" button. In other words, would the result of
        > clicking the Exposure correction box be different depending on
        > whether the "optimize" button had been clicked? Usually I was only
        > optimizing vignetting, but I did try some fine tuning of exposure.
        >
        > John
        >
        > John Riley
        > johnriley@...
        > jriley@...
        >
        >
        >
        >
        >
        >
        > [Non-text portions of this message have been removed]
        >
        >
        >
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