• DonaldBpanorama_fish_eye
    2365 posts
    2 years ago

    it was just a good article about luminance. and does contradict many members writings here.

  • IliahBorgpanorama_fish_eye
    976 posts
    2 years ago

    But you need to understand it.

    As I said, you misunderstood the article.
    Feel free to ask questions.

  • IliahBorgpanorama_fish_eye
    976 posts
    2 years ago

    Which article?
    Which histogram?
    What is exposure level?

  • JimKassonpanorama_fish_eye
    1738 posts
    2 years ago

    Not sure what you're talking about. Be explicit about the contradictions that you see. List them.

  • DeletedRemoved user
    2 years ago
  • DonaldBpanorama_fish_eye
    2365 posts
    2 years ago
  • DonaldBpanorama_fish_eye
    2365 posts
    2 years ago
  • TimoKpanorama_fish_eye
    300 posts
    2 years ago
  • DeletedRemoved user
    2 years ago
  • DonaldBpanorama_fish_eye
    2365 posts
    2 years ago
  • DonaldBpanorama_fish_eye
    2365 posts
    2 years ago

    I like the wording.

    Identical exposure settings shutter+apeture+iso

    Screenshot (6).png

    Screenshot (5).png

    Screenshot (6).png

    PNG, 1.9 MB, uploaded by DonaldB 2 years ago.

    Screenshot (5).png

    PNG, 2.0 MB, uploaded by DonaldB 2 years ago.

  • IanSForsythpanorama_fish_eye
    216 posts
    2 years ago

    what does these histogram tell you about the exposure
    photos.smugmug.com/Temp/Temp/i-snFsM5B/0/b8153607/O/exp3.jpg
    Notice how the patches show differently in the 2 histogram even when they represent the same lab values.
    How those values are shown in a histogram vary depending on what that distribution of data represents in a color space.
    (both are of jpg images and not raw)

  • DanHasLeftForumhelp_outline
    4254 posts
    2 years ago

    So what? I don't see the point you are trying to make.

    When using flash you have 2 exposures* to deal with - the ambient exposure* and the flash exposure*

    The flash exposure* can be set automatically by the camera using ETTL or manually.

    Even though the aperture, shutter speed and ISO are the same in both shots the total exposure* for Screenshot(5) was larger because more light from the scene hit the sensor due to the additional light added to the scene by the flash.

    The 2 luminosity histograms are about what I would have expected for those shots.

    * exposure - amount of light that struck the sensor per unit area while the shutter was open

  • TimoKpanorama_fish_eye
    300 posts
    2 years ago

    Both articles are misleading. Capturetheatlas more because he determines the exposure using LR histogram, not the RAW one.
    Artschoolportals article is better but I don't like the way they use PS Levels as example of exposure.

  • IanSForsythpanorama_fish_eye
    216 posts
    2 years ago

    They are not here is a hint for part of the scene you introduced more light thus altering the exposure

  • DanHasLeftForumhelp_outline
    4254 posts
    2 years ago

    The exif for the shots shows the aperture, shutter speed and ISO are identical for both shots but the exposure* is not the same as described earlier.

    * exposure - amount of light that struck the sensor per unit area while the shutter was open

  • DanHasLeftForumhelp_outline
    4254 posts
    2 years ago

    You are misunderstanding what is explained in those articles.

    Consider this image with pure red (255,0,0), green (0,255,0) and blue (0,0,255) pixels on a pure white (255,255,255) background.

    rgbDemo.jpg

    This is the RGB histogram for the image.

    rgbDemo_histogram.jpg

    This is the luminosity histogram for the same image.

    rgbDemo_lumHistogram.jpg

    A histogram of any kind - RGB, Luminosity, whatever - is just a frequency count of some values - RGB, luminosity, the number of various coloured cars crossing an intersection etc etc etc - and nothing more.

    What Is Happening Under The Histogram Hood

    rgbDemo_lumHistogram.jpg

    JPG, 24.4 KB, uploaded by DannoLeftForums 2 years ago.

    rgbDemo_histogram.jpg

    JPG, 59.6 KB, uploaded by DannoLeftForums 2 years ago.

    rgbDemo.jpg

    JPG, 22.7 KB, uploaded by DannoLeftForums 2 years ago.

  • DonaldBpanorama_fish_eye
    2365 posts
    2 years ago

    im not disputing that. have you a better way to show scene luminance ?