Thursday, January 26, 2012

Tip #43: Add Light to White

Shades of White
Canon 5D MarkII + Canon 17-40mm f4.0L @ 17mm

It’s been a long and cold day. Frozen to the core you wait for the light, the mist rising above an icy river, or a fleeting moment that crosses your path. You bury yourself in the snow to create a natural hide or lie prone on the ice to frame a dramatic composition. Regardless of how you contort your body, wrestle with the tripod or endure the cold, your suffering is for naught if you can’t nail the exposure. 
White subjects on a bright background will appear to confuse the meter and confound the photographer. Knowing how your camera “perceives” the light is the key to making your white subjects white. 
Ice Falls
Canon 7D + Canon 300mm f2.8L IS
Our eyes see reflected light - radiant energy redirected from a subject onto the retina. This reflected light is the same light that strikes the camera meter. Unfortunately your camera lacks the brain you have, and cannot distinguish bright from dark, or highlight from shadow. In the place of a brain, the meter is calibrated to a standard.  The standard, middle gray (often incorrectly described as 18% gray), allows the photographer to predict the way light will be translated into the final image. What follows are three key concepts about reflected light striking the meter:
  • The meter averages the reflected light and suggests an exposure that makes your subject neutral (middle gray).
  • Because white is lighter than middle gray, your meter will suggest that you underexpose a white subject. If you underexpose white, the subject appears to be middle gray.
  • Because black is darker than middle gray, your meter will suggest that you overexpose a black subject. If you overexpose black, the subject appears to be middle gray.
Trumpeter Swan (Cygnus buccinator)
Canon 1D MarkII + Canon 300mm f2.8L IS
To make white subjects appear white, you must first realize that the meter suggests how to make them middle gray. This is the the moment of liberation, as once this is accepted as fact, your brain can define the correct exposure. When photographing white subjects, do the following:
  • Switch the camera to manual.
  • Fill your frame with the white subject or use your built-in spot meter to meter white. 
  • Choose the aperture and shutter speed that balances your exposure.
  • Now follow Tip #43 and Add Light to White... To do this, compensate for the middle gray calibration by adding 1 and 2/3 to 2 stops of light to whatever your meter suggests. 
  • For example... if the meter suggests that the “correct exposure” is a shutter speed of 1/500 second and aperture of f/5.6, you should change your shutter to 1/125 (that’s plus two stops...) at f/5.6. Alternatively, you can keep the shutter speed fixed at 1/500 second and change your aperture to f/2.8 (plus two stops). Either exposure adds two stops of light, and you will have added light to white.
©2000-2012 / Bruce & Tamy Leventhal. All rights reserved. No image on this site may be used without permission.

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