Monday, May 12, 2014

Day 68, Learning 68: Under-expose or over expose for best shot?

There's an ongoing debate about whether to under-expose or over-expose your images for best results.  The underlying philosophy of both schools is that you will correct the issue in post production editing.  Those who argue for under-exposed images take the stance that detail can be recovered from shadow but not from blown highlights.  And that's true.  Those who argue for over-exposing the images correctly state that the upper end of the exposure spectrum contains more data.  Our cameras are designed to find detail on the brighter end.  So which is the best approach?

Like most photographers, I've inadvertently done both and had to deal with the catastrophe in post.  Over-exposed images abound when shooting outdoors because they look accurate on your camera's LCD when the sunlight makes things difficult to see.  I more rarely under-expose images, but it does happen.  In studio, your computer screen tends to make under-exposed images look correct-- your computer pushes light out, whereas a printed picture only reflects lights.  So over time I've struggled with correcting both issues.  My verdict: get it right in camera. 

My reasoning is simple:  when you darken an over-exposed image the contrast and vibrance remains washed out.  Attempts to correct the issue vary in their success because many images won't saturate naturally.  When you lighten an under-exposed image it rarely works to raise the exposure uniformly.  Often you have to lighten the subject more than the background.  And when you do selective exposure adjustments you torture pixels disproportionately.  The result is varying grain and an increase in artifacts. 

Right about now you're thinking that as far as "tips" go this blog post sucks.  Just "get it right in camera" is advice that is not only easier said than done but also a clich√©.  So let me offer something more concrete: 
  • Lightroom is great if you want to adjust exposure universally; however, it quickly creates harsh artifacts when using the brush tool to adjust exposure selectively (the gradation tool works better)
  • In Photoshop, use Curves and a mask to adjust selective exposure; you'll have fewer artifacts
  • The image on your LCD screen will consistently fail to represent the exposure and dynamic range of the image you just shot; check your histogram for a more accurate picture.  Check your histogram every half hour and every time you change location in a shoot
The above image was taken for HerStory, a start-up used clothing company. Its founder, "Lucky," is an ultra cool, ultra smart woman with an eye on both the past and the future. For this shoot, she was also one of the models-- picture above. Being Black myself, I can safely write that shooting people of color has challenges and rewards.  Indoors, the richness of skin color can be a real advantage; outdoors, it can be a liability in terms of exposure. Here, the sky was overcast and bright compared to her skin tones.  Full disclosure:  I over-exposed this shot significantly and had to "massage" it back to life in post.  It was a real pain. But worth it. Surprisingly, the solution was in "global adjustment" (the whole picture needed adjust, not just her face versus the background), so I did it in Lightroom by adjusting first the Blacks/Shadows and then the Exposure/Fill Light and until I found the right balance.

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