Aperture

Definition

The lens opening that controls how much light enters the camera.

Advanced

Aperture is expressed as an f-number such as f/1.8 or f/8. Lower f-numbers mean a larger opening, more light, and a shallower depth of field. Higher f-numbers mean less light and deeper focus. Aperture affects exposure, sharpness, and background separation.

Why it matters

It shapes subject isolation and exposure without increasing noise.

Use cases

• Portraits that require background blur
• Product shots needing full subject sharpness
• Low-light interiors without raising ISO

Metrics

• Typical range: f/1.4 to f/16
• Sharpness often peaks around f/5.6 to f/8 on many lenses

Issues

• Diffraction softening at very small apertures
• Missed focus when shooting wide open with shallow depth of field

Example

Shooting a founder portrait at f/2.0 to separate the subject from a busy office background.