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Histogram and Exposure

Discussion in 'Lighting Forum' started by CCRoo, Aug 9, 2011.

  1. CCRoo

    CCRoo Mu-43 Regular

    86
    Mar 22, 2011
    Dear Folks:

    Scenario:

    I am photographing my keyboard on my desk. There is light from the monitor and one lamp. It is very dim. I look through the viewfinder. The histogram shows a blob clumped to the left. I add exposure compensation and the white blob is now even distributed across the histogram. I get a nicely exposed image with a healthy histogram, but it the resulting image looks much brighter than what I see with my eye.

    Question:

    Don't I want to capture a photo with an exposure that gives me something close to what I see with my eye? Under what circumstances should to prefer the "healthiest" exposure as suggested by the histogram?

    Raoul
     
  2. RevBob

    RevBob Super Moderator

    Jun 4, 2011
    NorthWestern PA
    Bob
    Many folks prefer to expose with more of the histogram to the right side - exposing for highlights, which are somewhat harder to recover than shadow info. (I say many, because there are others who like more to the left, saving shadow info). The image on the LCD of the camera can be much different than what you see depending on how bright you have the display set in the menu options. Computer monitors are inaccurate as well, tending to a bluish cast. That's why many photographers have tools to calibrate their monitors.
    A balanced histogram is fine - you can play with the overall look in post-processing and fine tune it to your preferences.
     
  3. Hikari

    Hikari Mu-43 All-Pro

    Nov 26, 2010
    First, do you want to process your images or not.

    If you want to make the final image in-camera, then you expose so it looks good on the monitor. If you are going to process your image and shift the tones to re-create the image, then you have some more creative control with exposure.

    A few things to consider. The histogram cannot tell you the "correct" exposure no matter how it is distributed. It is simply a tool to evaluate what you have. If you are going to "expose to the right," realize it will solve some issues, but also create a few as well--increase in contrast and saturation, for example, which can be unnatural.
     
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  4. Howi

    Howi Mu-43 Veteran

    208
    Feb 23, 2011
    Sheffield
    Howard
    the histogram shows the spread of light in a scene NOT the exposure.
    Just because the bulk of the histogram is over to the left or right, doesn't mean the exposure needs changing - it will depend on whether the overall scene is above or below 18% grey - think of a black dog on a dark background compared to a winter snow scene.
    I prefer to use the histogram to look for 'blips' on the right of the histogram that would indicate overexposure - you wind down the exposure to see if there are any blips, then wind up the exposure until the farthest right 'blip' just touches the right hand edge.
    Shooting raw would allow you to push the blips past the right hand edge as they should be recoverable in PP.
    Only practice allows you to estimate how far you should go.
    There are times when it is impossible to prevent blown highlights, it is a fact of life.
     
  5. WT21

    WT21 Mu-43 Hall of Famer

    Feb 19, 2010
    Boston
    that is for you to decide, but dont be enslaved to replicating the scene. Get creative. Look at b&w shots. Properly processed b&w fir dramatic impact does not replicate close to what we see with our eye.
     
  6. CCRoo

    CCRoo Mu-43 Regular

    86
    Mar 22, 2011
    I took this pic tonight as darkness was falling. Added +7 ev -- overexposing to push the histogram to the right. The pics I took without the additional exposure were pretty noisy and fell apart in post. I played with this one and there is very little noise -- u can even make out some wisps of cloud in the sky. It looks like it was taken a little later on tho, when the sky was darker. It also has a more appealing, romantic look. Does it look fake?

    Building_002.
     
  7. Mellow

    Mellow Mu-43 All-Pro

    Aug 27, 2010
    Florida or Idaho
    Tom
    Good example. I'm amazed you didn't blow out more of the light inside the building.
     
  8. Bill

    Bill Mu-43 Regular

    176
    Apr 15, 2009
    Brisbane, Australia
    Bill (really)
    There's some informed and useful advice available from Michael Reichmann of Luminous Landscape. His article on "Optimising Exposure" is at:

    Optimizing Exposure

    There's also his earlier article on "Exposing (to the) Right" at:

    Expose Right
     
  9. CCRoo

    CCRoo Mu-43 Regular

    86
    Mar 22, 2011
    Thank you Bill!

    I actually read both those articles last weekend, motivated by the responses I got here on this thread.

    I like the expose to right bit but you sure have to know what you're doing in post! I am watching tutorials and stuff online to get a sense of what that workflow should be.

    (By the way, it kinda reminds me of shooting 16mm negative film -- getting that 'light print" as a reference for color timing later on.)

    Thanks!

    R