When a subject and background have similar extreme brightness values, these are called either high key or low key. High key images are extremely light with little contrast between subject and background and most shadow has been eliminated. Low key images are almost the opposite, a dark subject matter on a dark background, sometimes with subtle yet powerful highlights. Both high key images and low key images have a "graphic arts" feel that evokes an instantaneous response. In the case of high key photography, the response is usually a positive, pleasant one while low key photos evoke a sense of drama and foreboding.
When photographing either kind of scenario your camera will try to average out the shot, looking for a middle brightness value. You'll need to override the onboard computer. The easiest way to do that is with exposure compensation. On most Nikon Digital SLRs the exposure compensation button, a square button with a +/- on it, is next to the shutter release button. Hold down the exposure compensation button and turn the command dial to add or subtract light.
In high key scenarios, the natural tendency of the light meter will be to darken the image. Use the exposure compensation button to brighten it back up again.
In low key situations the response will be the opposite. The camera will attempt to brighten the image with a larger aperture setting. Use the exposure compensation button to darken it once again.
In this assignment look for high key scenes, lighter objects in lighter surroundings and low key scenes, dark objects hidden in shadow to photograph.
Also, spend some time at your at a magazine rack, perusing high-end fashion magazines. Specifically look for the use of high and low key images in advertisements. Review the message and consider why the art director chose this particular approach.
The tip of Lions Gate Bridge pokes out of a thick fog bank, lit from above and behind and within, rendering a high key image in peach as shadow is eliminated by light bouncing in every direction.
Again, fog is the culprit, softening and filling in the silhouettes of Burrard Bridge and the little Granville Island ferry seen in the foreground putt-putting across Vancouver's False Creek.
This high-angle, low key image of dories at dockside in Vancouver's False Creek has highlights, muted as they are, by the impact of the overall dark values.
A fire escape in Vancouver's Downtown Eastside deep in shadow, picks up highlights as the sun peeks over the edge of the alley.
All photographs were taken by Brian Grover.