Sony DSC-W80/W Sony® Guide to Digital Photography (Spring 2007) - Page 19

Taking your best shot CAMERA CONTROL Focus With all but the most basic cameras, image sharpness depends on adjusting the lens according to the distance to the subject. This, of course, is focus. During manual focus, you can consult the image in the LCD monitor, electronic viewfinder or through-the-lens optical viewfinder. You then adjust the focus until the subject is clear. On auto focus cameras, you can simply point and shoot. Typical auto focus (AF) systems detect the picture information coming off the image sensor. When contrast in the image is highest, the subject is in focus. When contrast is low, the image is out of focus. In this way, AF systems can work quickly and automatically. AF systems generally work quite well. But they can be thrown off by some tricky circumstances. • The challenge of darkness. Unfortunately, auto focus can run into trouble in low light, when the camera can't "see" contrast coming off the image sensor. • The challenge of composition. Most AF systems look towards the center of the frame. Unfortunately, if your subject is away from the center, the camera could well be focusing on the wrong thing. • The challenge of subject motion. If you're shooting kids, pets or sports, your subject can unexpectedly move toward or away from the camera. This means the camera-to-subject distance is changing from moment to moment - another challenge for AF systems. For these reasons, Sony has developed an array of powerful features for focus illumination, processing and control. 34 Sony focus features Face Detection Taking advantage of the BIONZ™ integrated circuit, Sony cameras accurately recognize - and focus on - the human face. Even a simple snapshot can trip up the automatic focus on a conventional camera. Sony's BIONZ™ processor solves this problem with Face Detection. As you shoot, the Face Detection function actually analyzes the data that make up your digital picture. In this way, Face Detection can identify and track up to eight faces at a time. Then the camera automatically adjusts for optimum focus, exposure, flash and even white balance on the faces themselves. The result is far more "good" pictures, far fewer rejects and re-takes. For the complete story on Face Detection and the BIONZ processor, please turn to page 26. AF Illuminator Accurate focusing, even in low light. Auto focus can run into trouble in low light, when the camera can't "see" contrast coming off the image sensor. That's why Sony offers AF Illuminator. The camera throws a special light on the subject prior to the shot, so the camera can "see" the subject's contrast. You get accurate focusing, even in low light. Multi-Point Auto Focus Automatically finds the focus, even when your subject isn't in the center of the frame. Sony solves common focus problems with Face Detection technology. (Sample photos for illustration purposes.) ? DISTANCE UNCERTAIN DISTANCE CERTAIN INCORRECT FOCUS CORRECT FOCUS While conventional focus (left) becomes very hit-or-miss in low light, our AF Illuminator (right) is right on target. (Sample photos for illustration purposes.) CAMERA CONTROL If the subject is off-center, cameras with a single focus point (left) tend to focus on the background. Sony Multi-Point AF (right) automatically brings the subjects into focus. (Sample photos for illustration purposes.) To keep up with fast action, the DSC-H7 and H9 15x zoom cameras incorporate a special version of Continuous AF (discussed in the Selectable AF section below). Instead of simply "keeping up" with your moving subject, the camera actually predicts where the subject will go in the interval between shutter release and image capture. This can be a key advantage in sports, especially if the subject is moving towards you. A super-fast 1/4000 second shutter speed helps to freeze the action on even the fastest midfielder. With the Flexible Spot AF of the DSC-H7, H9, and N2, you can frame the shot first, then use the camera controls to select the focus point. (Sample photo for illustration purposes.) Simple cameras simply focus on whatever is in the middle of the frame. But when you're taking a picture of two people, the center of the frame often shows the background - the wrong place to focus! In other cases, you'll get a more creative shot when the subject is off center. For these reasons, Sony developed Multi-Point Auto Focus. Some Sony cameras use a five-point system, automatically selecting the right focus points based on your composition. Cameras equipped with the BIONZ™ processor use a nine-point system. So you get critically accurate focusing under a wider range of conditions. To accommodate the full range of shooting situations, Multi-Point AF also includes switchable modes like Center AF, which uses only the center area, Spot AF, which uses only a tiny spot and Focus Lock, which enables you to focus first, and then frame the shot any way you want. Advanced Sports Shooting Mode Auto Focus Predictive auto focus knows not only where your little soccer player is, but where she's going. Selectable AF Perfect for unpredictable sports and fastmoving subjects, because you can choose a more responsive focus mode. Single Shot Auto Focus "locks" onto the subject as soon as you press the shutter half-way, which can be a problem when there's plenty of relative motion between the subject and the camera. • Single Shot AF is ideal for subjects that are standing still. The Auto Focus process doesn't begin until you press the shutter halfway. • Monitor AF speeds the shot, an important advantage in sports Continued on page 36. 35