Aperture Value (Av) Mode
Many intermediate and advanced cameras allow you to choose the aperture setting, and the camera sets the proper corresponding shutter speed. This setting is sometimes denoted as Av, which stands for aperture value. (Some cameras just go with a simple “A” for aperture priority.) You can typically access this setting via the mode dial or as a menu option.
Choose the aperture priority mode when you want to control depth of field. In other words, how much of your picture, from front to back, do you want in focus? Shallow depth of field is often used for portraits—your subject is in focus, but everything else is a little soft. Choose an aperture value of 2.0, 2.8, or 4 for this type of shooting situation. The lower the value, the shallower the depth of field will be, and less of the image will be in focus (see Table for specific depth of field settings).
When shooting landscapes, you’ll probably want “deep” depth of field, which produces a sharp image from foreground to background. Choose an aperture value of 8, 11, or 16 for deeper depth of field.
PRACTICAL EXAMPLE - Shooting an Outdoor Portrait with a Soft Background
If your camera has a portrait-shooting mode, it’s designed to “open up” the aperture to provide a shallow depth of field. Or, you can use aperture priority and select f-2, f-2.5, or f-2.8. Place the subject at least 10 feet away from the background, more if possible. This will soften the background detail, putting more emphasis on your subject. Set your zoom lens to the telephoto position (this enhances the soft background effect even more). Focus on the model’s eyes. Press the shutter halfway to lock” the focus. While still holding the shutter in the halfway position, recompose so the composition is just the way you want it. Then take the picture. If the lighting on the model’s face isn’t to your liking, force the flash on (see the “Flash Modes” entry later in this chapter), and shoot again. This setup should provide a nicely focused model against a softened background
Soft background portrait captured with Canon 10D and 85mm, f-1.8 lens set to f-2
