Instructions
Turn your digital or film camera on, and select a shooting mode by turning the exposure mode dial, located on the top of most single lens reflex cameras or by accessing the shooting modes through the menu screens.
Locate the "Spot Metering" button. If your camera does not have a spot metering button, change the metering program to "Spot." In this setting, the camera will set the exposure based on what is in the smallest portion of the viewfinder.
Hold the camera to your eye; position the viewfinder so the bright background occupies the center of the viewfinder. Press the spot-metering button, if your camera has one, or the shutter-release, located halfway down, to lock in the exposure. Re-compose the picture so your subject is in the picture.
Press the shutter release all the way down to take a picture that will silhouette your subject.