Photography Exposure and Depth of Field
Understand aperture, shutter speed, ISO, focal length, focus distance, and depth of field.
The exposure triangle
- Aperture: lower f-numbers admit more light and usually reduce depth of field.
- Shutter speed: longer exposures admit more light but increase motion blur.
- ISO: higher settings brighten the recorded image but usually increase noise or reduce dynamic range.
Equivalent one-stop changes
| Setting | One stop more light | One stop less light |
|---|---|---|
| Aperture from f/4 | f/2.8 | f/5.6 |
| Shutter from 1/250 s | 1/125 s | 1/500 s |
| ISO from 200 | ISO 400 | ISO 100 |
Depth-of-field factors
Depth of field generally becomes shallower with a wider aperture, longer focal length, closer focus distance, or larger sensor for the same framing. The exact result also depends on the chosen circle of confusion and viewing conditions.