The Aperture-Priority Mode (M-REC Mode Only)


Under the aperture-priority mode, you select an aperture and the camera chooses an appropriate shutter speed. The main purpose of using the aperture-priority mode is to control the Depth of Field. A shallow depth of field blurs the foreground and background, and makes the main subjects standing out from the surrounding.

Selecting the Aperture-Priority Mode

To use the aperture-priority mode, the first step is to enter the M-REC mode by turning the mode dial to M-REC.

The mode dial

The next step is to select the aperture-priority mode. To do so, hold the MODE button (below left) and turn the command dial (below right).

The MODE Button The Command Dial

While the command dial is being turned, the letters in the upper-left corner of the control panel and the lower-left corner of the LCD monitor will change (see next section below). The possible letters are P, A, S and M for the program, aperture-priority, shutter-priority and manual exposure modes, respectively. Once A appears, the camera is in the aperture-priority mode and you can release the MODE button.

Selecting an Aperture

When the camera is in the aperture-priority mode, turning the command dial selects an aperture. As the command dial is being turned, an aperture in the form of Fx.y appears on the LCD monitor and on the control panel. See the images below. Once the desired aperture appears, stop turning the command dial and the camera will use that aperture for subsequent shots. The corresponding shutter speed also appears on the LCD monitor so that you can determine if the aperture and shutter speed combination is an appropriate one. If the selected aperture may cause over- or under- exposure, the aperture on the LCD monitor blinks when the shutter release button is pressed halfway down. Should this happen, select another aperture and try again. If you are satisfied with the combination, press the shutter release button to take a photograph; otherwise, turn the command dial again for a new aperture setting.

Control Panel LCD monitor

The command dial can be turned in either direction: clockwise for larger aperture (i.e., smaller Fx.y) and counter-clockwise for smaller aperture (i.e., larger Fx.y). If the displayed aperture does not change while the command dial is being turned, this means you have already reached the maximum or minimum aperture. Turning the command dial causes the aperture to change in an increment or decrement of 1/3-stop. Note that if the corresponding shutter speed is longer than or equal to 1/4 second, it is shown in yellow on the LCD monitor to indicate that noise may appear in the recorded image. See the image below.

A yellow shutter speed means noise may occur in the recorded image

You can also use Exposure Compensation to increase or decrease exposure.

Why the Aperture-Priority Mode?

The use of aperture-priority mode is basically for controlling Depth of Field. The larger the aperture, the shallower the depth of field. A shallow depth of field makes the main subjects standing out. The following images were taken with a focal length of 115mm (35mm equivalent). The aperture used were F11.4, F6.8, and F4.0. The sharpness of the left image, from foreground to background, does not change very much. As the aperture becomes larger, foreground and background start to blur. In the right image below, which was taken using F4.0, the background becomes reasonably blurred so that the yellow flower in the middle is isolated from the background. Note also that the flowers in the foreground are also blurred. Therefore, when you need to isolate your subjects from the background/foreground, use a larger aperture.

F11.4 F6.8 F4.0
Click on the icon to see a larger image

The following images show another example of the relationship between depth of field and aperture.

F10.7 F5.4 F3.9
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For Those Technical-Oriented Minds

As discussed in Exposure Value: EV, when the shutter release button is pressed, the camera meter measures the incoming light and determines an EV (i.e., exposure value). In the aperture-priority mode, turning the command dial causes the aperture value to change, which, in turn, determines an appropriate shutter speed. This is shown in the figure below.