Photographer Camera Photography Contrast Dynamic

To understand how to get a correct exposure in digital cameras for a high contrast scene, it is important to first understand a bit about dynamic range. In simple terms, this means the difference in light between the lightest and darkest areas. One of the problems is the difference between what the eye can see and what the camera can capture.

The human eye has a much greater dynamic range than a camera. What this means is that our eyes will fill in the detail in the shadows and tone down the highlights so that what we see appears to have more even lighting than it actually does. As a matter of fact, the eye has a range of almost 24 f-stops, where a camera only has a range of about 10 f-stops and a practical limit of less than that.

If you are taking a picture of a green forest and green grass with a deep blue sky, the contrast between the different parts of the scene is fairly small. You can take a reading of most any part of the landscape and expect to get a reasonable exposure. But if the forest is very dark and the sky is very light, you probably have more dynamic range than your camera is going to capture.

This means that if you take a reading on the forest, the trees will be well lit, but the highlights in the sky will be blown out. Conversely, if you take a reading on the sky, the forest will be too dark and you will lose detail. The photographer must be aware of these differences in light and learn how to compensate.

One of the ways photographers deal with this is called HDR (High Dynamic Range) photography. This method involves multiple exposures and a lot of post processing and is outside the scope of this article. What we want to be able to do is compromise on the available lighting to attempt to get a good exposure across the range of our image.

To do this, you will need to take two or more readings. First put your camera in aperture priority and set a good aperture for the scene you are trying to capture, say f8 or f11. Then meter on a dark part of the scene and note the shutter speed the camera suggests. Now point at a lighter part of the scene and do the same. Next, move your camera setting to manual and put the aperture to the same setting you just used. Now set the shutter speed to a point midway between the two points you just noted and take a picture.

Check the image on the LCD and determine if you have captured what you intended. You may have to compromise to get the detail you want in the dark areas, or to get good colors and detail in the lighter areas. You may also have to take several readings from different parts of the scene. Finally, you will need to decide what part of the scene is the most important and make sure that this area is getting the best exposure.