Samsung Galaxy NX500 Camera User Manual (en)

Concepts in Photography
Aperture value and the depth of field
You can blur or sharpen the background of a photo by changing the size 
of the aperture. A large aperture gives your photos a shallow depth of 
field (DOF). Objects immediately in front of or behind your subject will 
be blurred, while the subject will be in focus. A small aperture gives your 
photos a deep depth of field. Objects far in front or far behind your subject 
and your subject will be in focus.
A photo with a deep DOF
A photo with a shallow 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