The aperture controls ‘depth of field’ and the amount of light travelling to the media card.
‘Depth of field’ is defined as “the area in the photograph that will be in acceptable focus
(near to far). The depth of field extends 1/3 in front of the plane of focus and 2/3 behind the plane of focus.
To control the ‘depth of field’:
1.) The larger the lens opening the shallower the DOF.
The result of shallow DOF is the background and the foreground will appear out of focus.
2. The smaller the lens opening, the greater the ‘depth of field’.
The result of a larger DOF is that the background and a portion
of the foreground will appear sharper.
It helps to memorize F-stops