05 0672327139_ch03 7/22/05 9:56 AM Page 88 1 Chapter 3 05 0672327139_ch03 7/22/05 9:56 AM Page 89 = 2 Focus is perhaps the most important FOCUS AND component in the success of an image. We all focus our eyes in the natural process of seeing, although lighting DEPTH OF conditions, attention span, and our emotional engagement with the scene impact exactly what we comprehend FIELD and react to. Thus, we use our eyes to bring the world into optical focus, but we also focus our minds to con- centrate our attention on the things we’re trying to understand. This chapter looks at the act of focusing with both our eyes and our minds. Getting the camera to render the world in sharp detail is the first step, while controlling what is in or out of focus allows us to cre- ate emphasis and to control the composition of the image. This chapter starts by outlining the basics of digital focusing techniques, and moves quickly to explaining how to control depth of field effects. The final pages of this chapter present tips for controlling focus and depth of field in specific types of scenes, including landscapes, objects, and close-up photography. 1 Fence 2 Montepulciano Altar Nikon D2H Nikon D2H, 1/125 sec, f/5.6 1/60 sec, f/4.5 Focal length 185mm Focal length 75mm 3 89 05 0672327139_ch03 7/22/05 9:56 AM Page 90 3 = Focus, Sharpness, and Depth of Field Focus and sharpness may sound like the same thing, but they really are two related but separate components of good photogra- phy. Sharpness refers to the crisp clarity and detail present in a photograph, while focus refers to the controls and action required by your camera to achieve the final sharpness result. Camera manufacturers have been on a holy quest to get us to forget about focus, assuring us that the cameras are automatic and intuitive enough to read the scene—as well as our minds. Although this is often true, there are times when the camera is less than intuitive, and we have to give it a nudge to get the focus right. To help you do that, we’re going to examine the mechanics behind focusing systems, explaining how they work and when you should shift from auto to manual. Focus is also one of the means by which you determine a photo’s depth of field. Depth of field is interesting because it controls what parts of the image are in focus as well as the overall clarity of the subject. Thus depth of field plays a significant role as a compositional element, controlling where the viewer looks and the speed with which his or her eyes move through the scene. These issues are covered in greater detail in the next chapter on composition, but for now, the important thing is to understand what depth of field is and how to control it. 90 Focus and Depth of Field • Chapter 3 05 0672327139_ch03 7/22/05 9:56 AM Page 91 4 5 6 Types of Autofocus that you can get the best results although its infrared signal can pro- 3 Val D’Orcia and avoid focusing mistakes. hibit you from focusing through Nikon D2H All of today’s cameras use some glass windows or other transparent 1/250 sec, f/7.6 The primary types of autofocus are form of autofocus, where the cam- objects. EV -1.33 era automatically detects the dis- known as active and passive sys- Focal length 78mm tance from the camera to the tems. Active autofocus sends out an Autofocus cameras define active 4 subject and sets the focus on the infrared signal that is reflected by areas within the viewfinder that act Montalcino Ring fly. With each generation of new the subject, allowing the system to as focusing zones. When one of Nikon D2H 1/100 sec, f/10 cameras, engineers continue to calculate the distance to the subject these areas is active, it reacts to EV -0.33 ISO 640 and set the focus. Passive autofocus areas of contrast and edge detail, advance the intelligence and capa- Focal length 75mm bility of digital autofocus, trans- systems determine the subject’s reflecting back information to both forming it from a clumsy yet distance from the camera based on passive and active systems for the 5 Olivetto Trees interesting concept into a func- the light and contrast in the subject reading. The number, placement, Nikon D2H tional piece of photographic tech- matter. and sophistication of these focusing 1/80 sec, f/4.5 nology. Having said that, although zones vary based on manufacturer Focal length 200mm Passive autofocus systems are less the technology has improved great- and price point of your camera, but desirable in that they are limited by 6 Duomo Statue ly, it is by no means automatic or it’s safe to say that all autofocus the available light; they have trouble Nikon D2H foolproof. It’s important to under- implementations are a marked focusing if there is little or no con- 1/500 sec, f/4.5 stand a bit about how the focusing advancement from where we were trast in the subject matter or if the EV -0.33 system in your camera works, so just a few years ago. scene is too dark. Active autofocus Focal length 75mm works well in most instances, 91 05 0672327139_ch03 7/22/05 9:56 AM Page 92 PHOTOtip Blurring on Purpose adding blur to the moving subject. This R emember that it’s not always nec- approach allows you to blur just the essary to keep everything tack sharp subject, while avoiding the inevitable in order to create a great image. There camera shake that comes from hand- are times when I intentionally create holding a slow shutter setting. images that are soft, and sometimes blurred beyond recognition. In other instances, I experiment with abstraction by setting the camera to a For example, many museums in Europe very slow setting and shooting out the don’t allow flash photography or window of my car while the car is tripods (even though they do allow you moving. Now, I don’t necessarily rec- to use your camera on its own). I think ommend that you do this if you’re the Experiment with intentional blur in low-light it’s their way of allowing tourists to get driver (I always have someone else at conditions. their snapshots without giving up any- the wheel as I’m shooting these kinds thing good to the professionals. Thus, of images). With some experimenta- if I’m standing in front of a great sculp- tion, you can achieve some interest- ture and I don’t have enough light to ing, fluid abstractions that would be capture a sharp image, I’ll introduce very difficult to emulate, even with some intentional camera shake to Photoshop’s filter set. In this second make the image even more abstract. If example, I was shooting at 1/13 of a I’m going to get camera shake, I’m at second at f/25, allowing for a well- least going to get shake that’s interest- exposed image with a great tonal ing. In the example shown here, I was range, in spite of the extreme abstrac- in the museum of the church of Santa tion. Croce in Florence, shooting sculptures from the original façade. ’ Intentional blur is an obvious way to imply motion within the image. A Motion-induced abstraction. tripod-mounted camera with a slow shutter speed can keep the static por- tion of the scene tack-sharp, while 92 Focus and Depth of Field • Chapter 3 05 0672327139_ch03 7/22/05 9:56 AM Page 93 7 8 Controlling Autofocus halfway to focus, and then recom- zone you want to use). Nikon has a 7 Duomo Scaffold III The skill you need with the auto- pose your image before pressing the button that toggles through all the (detail) Nikon D2H focus technique is being able to release button the rest of the way available zones. Most systems work 1/250 sec, f/7.6 quickly identify the desired focus down to take the picture. This well with a little practice, provided approach to focusing is similar to a that you understand what it’s doing. EV -1.33 point in your image and select the Focal length 78mm nearest focusing zone in the feature called Focus Lock, which is available on many advanced cameras. viewfinder. If the subject is not When to Switch to Manual 8 Duomo Scaffold III aligned with the focus zone of the Instead of pressing the shutter Nikon D2H Although autofocus can be a life- viewfinder, the camera will focus on halfway, Focus Lock allows you to 1/250 sec, f/4.5 saver in certain situations when you the background or the foreground, center the subject and press the EV +0.33 need to react quickly to get the shot, and the subject will be out of focus. Focus Lock button to set the focus, Focal length 75mm then recompose the scene as you can also see that it has its limita- If your camera is older or more of a desired. tions. As a result, be mindful that point-and-shoot model, you might you can switch your SLR camera not be able to select specific focusing Digital SLRs and advanced all-in- from autofocus to manual mode to zones, although your owner’s manual one digital cameras allow you to set the focus exactly where you want should outline where the focusing select which focusing zone is active it by adjusting the focus ring on the zone is and how to optimize focus.