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
(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
M for the
program, aperture-priority, shutter-priority and manual exposure modes,
appears, the camera is in the aperture-priority mode and you can release the
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.
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
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.
Click on the icon to see a larger image
The following images show another example of the relationship between depth of
field and aperture.
Click on the icon to see a larger image
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.