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EV Compensation You Can Use

By Mike Pasini, Editor
Imaging Resource Newsletter

Whether your camera offers multi-mode metering or not, it probably has exposure compensation. Why? Because not even film can capture the entire brightness range of the typical scene before you. About 1:10,000.

"How you map that 1:10,000 brightness range . . . to the 1:100 or so you end up with is what exposure is all about."

Black-and-white prints have a brightness range of only about 1:100. How you map that 1:10,000 brightness range in front of you to the 1:100 or so you end up with is what exposure is all about.

And rather than letting the camera guess (or fudge with multi-mode metering) what's important in your shot, exposure compensation using EV (or Exposure Value compensation) can give you the deciding vote.

Your camera's built-in exposure meter calculates the average brightness of the scene and sets the camera to expose for a middle gray (18% gray is the midpoint of reflectances from black to white). Most of the time that's fine. Or nobody would be buying point-and-shot cameras.

But when you're faced with special factors like the reflections of snow or sand, or metallic highlights, you have to fudge the exposure to compensate.

Try this experiment to see exactly what we mean. Find a nice bright flower to shoot in some absent neighbor's garden. Get close enough to just about fill the frame with the colorful petals and notice the range of color in your LCD viewfinder. Pretty full. Now step back so the flower is just part of the picture. Suddenly it's burned out. Nothing but white. No detail.

In trying to "see" the darker garden details, your automatic exposure has become blind to the finer shades of the flower.

That's when you need EV compensation.

Just tell your camera to underexpose the scene and your flower will retain its color. And when your subject is dark, just tell the camera to overexpose the scene. You know, like when the sun is behind everyone in the picture and you want faces not silhouettes.

How high or low should you set your EV compensation? Well, it depends on your camera. Some cameras permit half-stop adjustments, some just full stops. And the range may vary, too, but it's usually two full stops over and two full stops under. The trick is to experiment. After all, with a digicam, you don't have to wait an hour to find out the results.

This article is reprinted from The Imaging Resource Digital Photography Newsletter,
Advanced Mode Column, published November 4, 1999

 

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