| Depth of field is a photographic term that | | | | subject from the background and foreground. |
| describes the area in a photograph that is in sharp | | | | As I indicated earlier, which focal length you |
| focus. Although only a single plane in an image can | | | | choose will depend on what you are attempting |
| be in true focus, various lenses and certain lens | | | | to show in the photo. Suppose you are shooting a |
| setting can create the appearance of a much | | | | group of people seated around a table. Your goal |
| wider area of focus. You can alter DOF by | | | | will be to have everyone in focus, so a wideangle |
| changing the aperture of the lens, the focal length | | | | focal length will be the most appropriate choice. |
| of the lens or the distance to the subject. | | | | On the other hand, maybe you are shooting a |
| A more academic approach to DOF would include | | | | craftsman working in his crowded shop. You can |
| discussion of things like circle of confusion and | | | | use selective focus to isolate the man from the |
| hyperfocal distance. For all practical purposes, | | | | background. A long lens will display only the man in |
| however, you don't have to know about these | | | | focus, while the rest of the image fades into a |
| advanced topics to include DOF effects in your | | | | soft blur. |
| photos. | | | | Many zoom lenses include both wide angle and |
| There is no "good" or "bad" depth of field. | | | | telephoto settings. This means depth of field |
| Depending on your subject and your artistic vision, | | | | produced by a zoom lens will vary with the |
| you may choose to use a wide DOF for some | | | | selected focal length. |
| images and a very narrow DOF for others. If you | | | | The final way to control DOF is with lens aperture. |
| are shooting a portrait, you may want a shallow | | | | Larger lens openings (smaller f-numbers) create |
| DOF, so only the person's face is in sharp focus. | | | | shallower depth of field. Smaller lens openings |
| If you are shooting a front three-quarter shot of | | | | create greater DOF. Think about what happens |
| a car, you may require a wide DOF, so | | | | when you are trying to make out a sign that is |
| everything from the grille to the rear bumper | | | | too far away to read. Most people squint, causing |
| appears tack sharp. | | | | their eye opening to be smaller and the sign to be |
| There are three ways you can control depth of | | | | more focused. |
| field: | | | | Your camera lens works exactly the same way. |
| 1: You can move farther away or closer to your | | | | When you open the aperture to allow more light |
| subject. | | | | to pass through the lens, DOF becomes shallower. |
| 2: You can switch the lens focal length. | | | | Stop the lens down to a smaller f/stop and DOF |
| 3: You can change the aperture of the lens to a | | | | becomes more pronounced, causing more of the |
| larger or smaller opening. | | | | image to appear in focus. |
| Let's look into these methods more closely. | | | | Now that you understand the concept behind |
| Depth of field varies as you move closer or | | | | depth of field, consider how you can use this |
| farther away from your subject. If you have | | | | knowledge to improve your photographs. I've |
| ever shot closeups with a macro lens, you | | | | already discussed how you can select an |
| undoubtedly noticed that only your subject was in | | | | appropriate focal length for a particular subject. |
| focus, while everything else was dramatically | | | | But the available DOF options are much more |
| fuzzy. Because the lens was extremely close to | | | | complex. Great photographers learn how to |
| the subject, the image exhibits very shallow DOF. | | | | manipulate DOF to create arresting photos. |
| The same effect, although less pronounced, | | | | Isolating a subject from the background, whether |
| occurs when shooting any subject. The closer a | | | | it is a flea or a battleship, always produces |
| lens of a particular focal length is to the subject, | | | | interesting subjects. Most photographers choose |
| the less apparent depth of field you will see in the | | | | to shoot architectural subjects with a wide angle, |
| resulting photograph. Don't expect to see a great | | | | because the wide focal length allows them to |
| difference in DOF unless you move the lens | | | | capture the whole building while standing close to |
| significantly. When you photograph something | | | | it. To capitalize on shallow DOF, however, you |
| from afar, such as Big Ben or the Grand Canyon, | | | | could walk several blocks away and shoot with a |
| chances are the entire subject will be in focus, | | | | telephoto, separating the building from other |
| because the subject was far away from the lens. | | | | structures nearby. |
| The second way to manage DOF is by changing | | | | Should the subject require many different |
| lens focal length. Wide angle lenses tend to | | | | elements to be in focus, you now know that you |
| exaggerate the apparent depth of field, while | | | | can achieve that result by either moving farther |
| telephoto lenses usually offer a shallow field of | | | | away, switching to a wide angle lens or selecting a |
| focus. The result is that almost everything will | | | | smaller aperture. Naturally you can combine all |
| tend to appear in focus with a wide angle lens. In | | | | these techniques to increase the DOF even |
| contrast, a telephoto will allow you to isolate your | | | | further. |