Choosing the Right Aperture
The choice of aperture has a big impact on your outdoor photos because it affects the depth of field (how much of the photo is in sharp focus from front to back). If you use Auto or Program mode, you have no choice in aperture settings; with these settings, the brighter the scene, the smaller the aperture and faster the shutter speed. If you're shooting portraits or landscapes, though, you'll want to select your own aperture.
For portraits (see Figures 7.1 and 7.2), you want to focus on the subject and blur out the background. To do this, select a wide aperture (f/1.8 to f/5.6) because these apertures have shallower depth of field than narrower apertures. If you cannot select a wide aperture in Aperture Priority mode without overexposing your photo, select a low ISO (200 or less).
Figure 7.1 What's the subject? 1x zoom and f/7.5 aperture combine to make the background rival the subject for sharpness.
Figure 7.2 There's no question about the subject this time! 5x zoom and f/5.6 aperture help blur out the background (ISO 200).
For landscapes (see Figure 7.3), you usually want the entire photo to be in focus. If the landscape has objects at different distances from the camera, you might need to use narrow apertures (f/8.0 and smaller) to achieve the desired depth of field. When you use narrow apertures, you must watch out for shutter speeds that are too slow to hand-hold successfully.
Figure 7.3 A 3x (55mm) lens and narrow f/14 aperture capture both the near bank tree and the far side of the New River Gorge bridge in sharp focus.