Facebook Pixel Using Exposure Bias To Improve Picture Detail

Using Exposure Bias To Improve Picture Detail

AV +- Exposure Bias can be a very handy tool on a digital camera but most people aren’t aware of its use. Most DSLRs have had the feature for a while and now more and more compact digital cameras are adding it. For those who have never experimented with this useful feature, Peter Carey delivers this quick primer demonstrating how it can help improve your photographs.

Let’s face it, today’s digital cameras come packed with a LOT of features and buttons we never use. Snow Scene Mode, flash bracketing, infinity mode and the list goes on. One feature that deserves a bit more attention is automatic exposure bias. It goes by various names depending on the brand of camera you own but the premise is the same; adjust the exposure a certain amount of f-stops either over or under the camera’s metering. Its use is usually quick and easy and the results can make the difference between a washed out photo or one with plenty of depth to it.

There are times when your camera will have difficulty picking the right exposure. Some scenes that cause this are:

  • Snow pictures with a dark subject in the foreground
  • Bright, cloudy skies
  • A single light source such as a candle


The common theme here is high contrast. While the human eye and brain do an amazing job of adjusting to high contrast situations, digital cameras have to compromise much more so. When using a general evaluative mode, your camera looks at the whole scene and picks a median setting to compromise between the highs and lows. The problem with using the camera’s default settings is highlights tend to get washed out during this compromise, which are hard to recover correctly in post-processing (as compared to dark areas where there is less loss of data).

To overcome this limit, use your camera’s Exposure Bias adjustment to either underexpose or overexpose what the camera believes are the correct settings. Below is an example showing the difference in detail of the mountain Cho Oyu on the Nepal/Tibet border. Both images are straight out of the camera and cropped as close as possible in exactness. The left image has no bias. The right image is underexposed by 1 2/3 stops. Following the images are the histograms for each zoomed picture.

Cho

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Zoomed

Zoomed

pic1

pic2

Click on each image to see a larger view.

While the second shot is notably darker, the amount of detail retained is the important factor. The histogram for the first shot shows evidence of some slight clipping while the brights are pushed near their limit. The second shot is far more balanced and will be an easier image to pull detail from.

If you happen to be shooting in RAW mode, you already have about 1 decent stop of latitude and will not need to use the Exposure Bias as frequently. But if you’re shooting in JPG mode most of the time, it’s vital to make sure the details are retained for crispness and clarity. So experiment a bit the next time you find yourself in a high contrast situation. You might find your brain is sometimes a better judge of the lighting in a situation than your camera.

Peter is an avid photographer currently traveling through South America who enjoys travel, portraiture and wildlife photography. A travel related blog of his past and current shenanigans can be found at The Carey Adventures. He also hosts a Photo of the Day RSS feed found here.

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Peter West Carey

Peter West Carey leads photo tours and workshops in Nepal, Bhutan, Seattle, Portland, Los Angeles and beyond. He is also the creator of Photography Basics - A 43 Day Adventure & 40 Photography Experiments, web-based tutorials taking curious photographers on a fun ride through the basics of learning photography.

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