Defining Depth of Field
As you can see in the composite image above, depth of field can vary greatly from photo to photo. Technically, depth of field is determined by the amount of subject matter that stays in focus both in front of, and behind, the point of focus. So before you make changes to your depth of field, you first need to be able to focus the lens of your camera.

If this concept of "depth of field" isn't immediately clear to you, it may be easier to think in terms of "depth of focus": in the bottom half of the composite above, every element from front to back is in focus, thereby having a long "depth of focus".

Conversely, the top half of the composite would be described as having a short depth of field (or depth of focus), because while the subject is in sharp focus, the background is blurry, or "soft".

Once you have read this lesson, however, you will know how to adjust the settings in your EVOLT E-510 to create the look you want every time.

Controlling Your Focus
There are five focus modes in the EVOLT E-510:

• Single Auto Focus (S-AF)
• Continuous Auto Focus (C-AF)
• Manual Focus (MF)
• Single Auto Focus + Manual Focus (S-AF+MF)
• Continuous Auto Focus + Manual Focus (C-AF+MF)

The Auto-Focusing modes allow you quick and accurate focus, and are the most popular focusing methods in today’s SLR photography.

There are however, situations where you may wish to adjust the focus point for a more artistic view. Manual Focusing enables you to be very precise in choosing your point of focus. When using the S-AF+MF or C-AF+MF, you can use the camera's auto-focusing system to quickly focus on the subject and then, using the front focusing ring on the lens, fine tune your focus to achieve the exact image you want.

To change the AF mode, press OK to activate the LCD display and use the Arrows to select the AF field located above and to the left of the frame counter (figure 1). Press OK to enter the AF menu. Then, use the Arrows to select the desired AF mode and press OK to confirm the selection (figure 2).

Alternative Access To Modes
With the E-510 accessing common camera settings such as AF modes, White Balance, ISO, and Metering Modes is even easier via the handy shortcut buttons. Each arrow on the key pad corresponds to a specific camera menu, which can be accessed by simply pressing the button assign to that menu (figures 3 & 4).

Single Auto Focus
When you press the shutter button down halfway in the S-AF or S-AF+MF modes, the camera locks the focus on whatever is in the center of the frame and maintains this focal point until either pressure on the shutter is released or until the shutter is pressed the rest of the way down. It is best to take pictures of relatively still subjects in either of these modes. We chose this mode for photographing our subject in this lesson.

Note: If the background is centered in your frame, your subject may be rendered out of focus. In order to prevent your subject matter from going fuzzy, there is a trick you can use to make sure it stays in focus no matter what happens to be in the center of your frame: simply position your camera so that what you want to be in focus is in the center of the frame, press and hold the shutter button down halfway, compose the shot the way you like, and press the shutter the rest of the way down to release the shutter.

Controlling Depth of Field
Once you know how to set your focus within your frame, you can start taking pictures, but keep in mind that if the shooting mode of the camera is set to P ("Program", or automatic), or any of the SCENE modes, you will not be able to control your depth of field, as the camera will make automatic settings depending on the availability of light. In order to control your depth of field, you need to manually adjust your aperture and shutter speeds.

To manually adjust your aperture and shutter speed settings, first turn the Mode Dial on the top of the camera to M (figure 5).

Aperture
The most important thing to remember is that your aperture setting controls your depth of field. The smaller your aperture number, or "f/stop", the shorter your depth of field will be. You can adjust the aperture number by pressing the (+/-) button and turning the Control dial to select the desired aperture (figures 6 & 7).

Shutter Speed
Once the aperture is set, the shutter speed can be configured to accommodate the proper exposure. One of the nice things about digital cameras is that if you take a shot and it's either too light or too dark, you can immediately make adjustments to the shutter speed until you render the proper exposure. Likewise, if you want to maintain a certain shutter speed, you can make adjustments to the aperture to render the proper exposure.

To adjust your shutter speed in the Manual mode, simply turn the Control dial until the desired shutter speed appears in the shutter speed field (figure 8).

To demonstrate different depths of field, we took some portrait shots in a shaded area in front of a picket fence at different aperture settings. In the camera, we set the ISO to its lowest setting (100), set the Image Quality to RAW, and set the White Balance to Daylight (5300K) to match the color temperature of daylight.

To learn more about adjusting these settings, check out the EVOLT E-510 Basic Start-up lesson located on this site.

We then started off with a long depth of field by setting the aperture to f/22 and then took a few shots at different shutter speeds until we arrived at a good exposure (figures 9, 10 & 11).

In the result shot, notice how the picket fence in the background is just as focused as the subject. This is because our depth of field (f/22) is deep, allowing everything to stay in focus from front to back. Remember, the higher the aperture number, the smaller the diameter of the aperture opening will be, and the deeper your depth of field will be.

Next, we wanted to achieve a shorter depth of field by setting the aperture to f/3.5 (its widest setting). We adjusted the shutter speed to accommodate a good exposure, focused on the model, and took another shot (figure 12 & 13).

In the result shot, notice how the picket fence in the background is now somewhat fuzzy. This is because the focus area, or depth of field, is limited to the area around the model. The advantage to a limited depth of field is that the viewer's attention is drawn to whatever is in focus. In this case, it happens to be our model.

Next, we wanted to demonstrate how to control the position of focus within the frame. Remember the Focusing Trick we mentioned before? This is where you can apply it and see results.

With the aperture still set to f/3.5, we swung the camera down to focus on a blade of grass a couple of feet from the camera, pressed and held the shutter halfway down, returned to the original view and pressed the shutter the rest of the way down (figure 14).

With the model and fence out of focus, our attention is drawn to the blade of grass in the foreground, whereas in previous shots, the grass is barely noticeable.

Next, we swung the camera to the left to focus on the back fence, pressed and held the shutter halfway down, returned to the original view and pressed the shutter the rest of the way down (figure 15).

Again, notice where the eye is drawn now: past the model to the crisp lines of the fence. You can see how determining your point of focus is crucial when shooting with a limited depth of field.

Depth Of Field With A Telephoto Lens
Next, we decided to substitute our standard Zoom lens for a Telephoto lens. With a longer focal length than standard or wide-angle lenses, the Telephoto lens enables you to minimize the amount of background in your shot, and keep the perspective of your subject looking natural. It also allows you to create the crop you want and to focus more on your subject. As with a traditional SLR camera, these interchangeable lenses are easy to switch out.

To learn more about switching out lenses, check out the EVOLT E-510 Basic Start-up lesson on this site.

After attaching the lens, we maintained the distance between the camera and the model for comparative purposes. Then we refocused on the model, positioned the camera to render an interesting composition, and took shots at both f/22 and f/3.5 (figures 16, 17 & 18).

Again, notice the difference between the two settings. Figure 17 (shot at f/22) has everything in focus while Figure 18 (shot at f/3.5) focuses primarily on the subject. And with the tighter crop afforded to us by the Telephoto lens, the attention is drawn even more toward the subject.

Other Examples of Depth of Field
Depth of field is considered by most studio photographers to be even more critical when shooting product or macro shots. In studio or still life situations, it's usually best to use Manual Focus in order to set your point of focus precisely.

Here, we took a few shots of some small chess pieces to further examine the effects of varying depths of field. We placed three pieces on a white table next to a 12-inch ruler, each piece six inches apart and placed a medium soft box with a continuous, Tungsten-balanced light head attached over the pieces to serve as our primary source of light. In the camera, we changed the focus to Manual and created a Custom White Balance setting to match the color temperature of the light unit (3200K).

NOTE: To learn more about adjusting your White Balance settings, check out the EVOLT E-510 Basic Start-up lesson on this site.

After manually focusing on the middle piece, we took shots at two different aperture settings: one at f/3.5 (figure 19) and one at f/22 (figure 20). Figure 21 is a composite of both results.

Notice in the top half of the composited image how the chess pieces in the foreground and background are slightly out of focus, or "soft". This is because the focus area, or depth of field, is limited to the area around the center chess piece.

Now notice in the bottom half of the composited image how the chess pieces in the foreground and background are just as focused as the center piece. This is because our depth of field (f/22) is deep, allowing everything to stay in focus from front to back. Remember, the higher the aperture number, the deeper the depth of field.

Also, keep in mind that your depth of field will fall off both in front and in back of your focal point. How quickly it falls off depends on your aperture setting.

To further illustrate, we focused on the front chess piece and again took shots at the same aperture settings as before: f/3.5 and f/22 (figure 22).

Notice how quickly the focus drops off in the top half (f/3.5), whereas the falloff is barely perceptible in the lower half (f/22). The advantage to a long depth of field is that every element in the shot is clearly identifiable because it is in focus. The advantage to a limited depth of field is that the viewer's attention is drawn to the specific elements that are in focus.


Depth Of Field With A Macro Lens
Now that you know how to control your focus and depth of field, let's examine how a Macro Lens can magnify the effects of depth of field and how it works to increase the size of small items, such as these chess pieces.

Before we attached the Macro Lens, we placed one chess piece as close to the camera as possible while still maintaining sharp focus. Then we placed another piece one inch closer to the lens and again took shots at the same aperture settings: f/3.5 and f/22 (figures 23 & 24).

At the f/3.5 setting, only the rear piece stays in focus. And because of its distance from the lens, the rear piece is rendered as large as can be while still maintaining focus. At the f/22 setting, however, both pieces are in focus because of the longer depth of field, yet this is about as large as we can render the front piece without it going soft.

We then replaced our Zoom lens with a Macro Lens and were able to place the front piece about 3 inches closer to the camera while still maintaining sharp focus. Again, we positioned the second piece 1 inch back from the first and took shots at the same aperture settings: f/3.5 and f/22 (figures 25 & 26).

Notice how quickly the focus drops off in the top half even at 1 inch away! The Macro Lens not only magnifies the subjects but also reduces the depth of field significantly.

To illustrate this point even further, we moved the rear piece another inch back (Figure 27) and took another two shots (figure 28).

Look at the back piece now. At 2 inches back from the first piece, it's almost unrecognizable at f/3.5, and there is even a noticeable difference at f/22.

By experimenting with different aperture settings in your E-510, you will be able to achieve the look you're after in most any situation.