|  | This photo is a composite of two photos taken at the same exact location only moments apart. Each one, however, has a significantly different look from the other. An experienced photographer would identify the bottom half of the composite as having a long “depth of field” because both the subject and the background are in sharp focus. | | 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”: every element from front to back in this photo is in focus, thereby having a long “depth of focus”.
On the other hand, the top half 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”.
Unless you have studied photography, you may not know how to control your depth of field. Once you have read this lesson, however, you will know how to adjust the settings in your C-740 Zoom to create the look you want every time. |
Topics Covered: -
- Defining depth of field
- Controlling your focus point
- Setting your camera to the Manual exposure mode
- Adjusting your aperture
- Adjusting your shutter speed
- How your zoom affects your depth of field
Equipment Used: Camera/Media - Olympus C-740 Zoom digital camera
- Olympus 128MB xD-Picture card
- Sturdy tripod
| As we've seen above, depth of field is determined by 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 know how to use the auto-focusing function of your camera. Once you understand how auto-focusing works, you can use it in a very controlled way. |
To turn the camera on, simply press the red power button on the back of the camera. If the Main dial is set to a shooting mode (P, A/S/M, etc.) the lens will extend into position, even if the lens cap is attached (a big improvement over previous models!). If the Main dial is set to the Playback mode (green triangle), the lens will not extend (figure 1). | 
Figure 1 |
| The C-740 Zoom uses an auto-focusing system for image capture, which means that the lens will focus on whatever happens to be in the center of the frame. So if your subject is in the center of the frame, your subject will be in focus. 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.
FOCUSING TRICK: 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), you will not be able to manually adjust your depth of field, as the camera will make automatic settings depending on the availability of light. |
Figure 2 | APERTURE AND SHUTTER SPEED
In order to control your depth of field and your exposure in the C-740 Zoom, you need to manually adjust your aperture and shutter speeds. To manually adjust your aperture and shutter speed settings, first turn the Mode Dial to A/S/M (figure 2). |
| The A/S/M represents three separate shooting modes: Aperture Priority (A), Shutter Priority (S), and Manual (M). In order to adjust the aperture and shutter speeds independently of each other, you need to set the mode to M. To do this, activate the main Menu and press the Right arrow button to enter the CAMERA Menu. Scroll down to the A/S/M menu, choose M and press the OK/menu button to exit the menu (figures 3 & 4). |
If the LCD is not already displaying an image through the lens, press the Monitor button and you will see a set of numbers at the top of the screen (figure 5). | 
Figure 5 |
Figure 6 | 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. On the LCD, the second group of numbers displays your current aperture setting. You can adjust the aperture with the left and right arrow keys (figure 6). |
| The first group of numbers displays your current shutter speed. Once the aperture is set, the shutter speed can be adjusted 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. |
 Figure 7 | You can make adjustments to your shutter speed with the Up and Down arrow keys
(figure 7). |
| 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 SHQ, and set the White Balance to 5500K to match the color temperature of daylight. | | We then started off with a long depth of field by setting the aperture to f/8. We then set the shutter speed to 1/60th of a second, focused on the model (in the middle of the frame), and took a shot (figures 8, 9, & 10). | 
Figure 8 | | 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/8) is deep, allowing everything to stay in focus from front to back. Remember, the higher the aperture number, the deeper the depth of field. |
| Next, we wanted to achieve a shorter depth of field by setting the aperture to f/3.7. We then set the shutter speed to 1/500th of a second, focused on the model, and took another shot (figure 11 & 12). | | 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. |
Figure 13 | 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/3.7, 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 13). | | 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 14). | 
Figure 14 | | 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 critical when shooting with a limited depth of field. |
| Next, we decided to zoom all the way in with the lens. With the lens at a longer focal length than at the wide setting, it 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. |
Figure 15 | After adjusting the zoom lens to the telephoto position, 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/8 and f/3.7 (figures 15, 16, & 17). | Topics Covered: -
- Defining depth of field
- Controlling your focus point
- Setting your camera to the Manual exposure mode
- Adjusting your aperture
- Adjusting your shutter speed
- How your zoom affects your depth of field
Equipment Used: Camera/Media - Olympus C-740 Zoom digital camera
- Olympus 128MB xD-Picture card
- Sturdy tripod
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