17
Concepts in Photography
Aperture value and the depth of field
You can blur or sharpen the background of a photo by controlling the
aperture. It is closely related to the depth of field (DOF), which can be
expressed as small or large.
A photo with a large DOF
A photo with a small DOF
The aperture housing contains several blades. These blades move together
and control the amount of light passing through the center of the aperture.
The number of blades also affects the shape of light when shooting night
scenes. If an aperture has an even number of blades, light divides into an
equal number of sections. If the number of blades is odd, the number of
sections is double the number of blades.
For example, an aperture with 8 blades divides light into 8 sections and an
aperture with 7 blades into 14 sections.
7 blades
8 blades
