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What is Depth of Field?

Learn How to Set Depth of Field With a DSLR

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Depth of field in photography refers to the portion of the photograph that will be in focus from the front of the photo to the back. Just how much of your photograph remains in focus depends on the type of lens you're using and your camera's capabilities.

Some shots will make use of a large depth of field. Other photos look better with a small depth of field. You can control depth of field by changing the aperture of the lens, which is designated by an f-stop number. The f-stop number determines the size of the aperture, or opening, of the lens. A larger opening allows more light to enter the lens than a smaller opening.

A high f-stop number equals a small lens aperture and a large depth of field. A small f-stop number equals a large lens aperture and a shallow depth of field.

Making use of different types of depth of field can give your photographs vastly different looks. Continue reading to learn more about how depth of field works and how you can use it in your photographs.

  • A shallow depth of field means that only a small segment of the photo will be in sharp focus, while the foreground and background will be out of focus. A large depth of field means most of the photo will be in focus from front to back. Try thinking of the scene you’re going to shoot as a 3D scene, and depth of field determines the "slice" of that 3D scene that will be in focus.

  • One of the easiest things you can do with a DSLR to create a shallow depth of field is to make use of the "portrait" mode -- usually marked with a small icon of a woman’s head on the mode dial. Portrait mode automatically makes the depth of field shallower, leaving the subject in focus and the background out of focus. This is a great photography technique, as having an object in sharp focus in front of a fuzzy background will make the subject of the image really stand out.

  • If you want most of the photo in focus, you'll then need to use a large f-stop number. You also might try switching to manual focus mode and turning the focus to infinity. The DSLR’s lens then will leave as much of the photo in focus as possible.

  • With your DSLR camera, try turning the mode dial to the A setting, which stands for aperture priority mode. In this mode you select the aperture, which is the size of the opening through which the light enters the camera, and the DSLR camera will set the other settings automatically. With an aperture setting of a smaller number, the depth of field will be shallower, meaning a smaller portion, or "slice," of the photo will be in focus.

  • Look for a lens that has a more options for setting the aperture. All lenses offer different maximum and minimum aperture settings, and better lenses will have a wider range available. Most interchangeable lenses for DSLR cameras will offer a wide range of apertures. Other lenses, such as those found on point and shoot cameras, will have a very limited aperture range. To give yourself improved results with depth of field, consider making use of a lens that gives you a wide range of options for setting the aperture.

  • If you don't have a lens that can shoot at the low f-stop number you need to create a shallow depth of field, you also have the option of moving your subject. Through this technique, you can simplify the process of creating a shallow depth of field by placing the subject close to the camera and keeping the objects in the background as far away from the subject as possible. The background will naturally be slightly out of focus if it’s farther away from the subject on which you’re focusing, even if you're stuck using a higher f-stop number than you want to use.

When initially learning how to set and make use of the aperture, it’s a good idea to shoot a lot of photos, giving yourself the opportunity to experiment with various settings to see which setting works well for you.

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