Aperture (f-stop)technical
The size of the lens opening. Wide (f/1.8) blurs the background; narrow (f/11) keeps more in focus.
See it
Drag to see the effect (illustrative simulation).
Wide open — background melts awayf/1.2
Aperture sets how much light enters and how shallow the depth of field is. Lower f-numbers = wider opening = more background blur and more light. Higher f-numbers = more of the scene sharp, but less light and (past ~f/16) softening from diffraction.
Use this when
- Portraits with blur: f/1.8-f/2.8
- Group photos: f/5.6-f/8
- Landscapes: f/8-f/11
Common mistake: Shooting landscapes at f/16+ and losing sharpness to diffraction.