f/4
Aperture
4.0
Stops less light than f/1
6.25%
Light vs f/1
86.7 cm
DoF: 50 mm at 3 m (FF)
5.4 µm
Airy disk diameter
Depth of field at f/4 (full frame)#
| Focal | at 1 m | at 2 m | at 5 m | at 10 m | Hyperfocal |
|---|---|---|---|---|---|
| 16 mm | 1.17 m | 27.5 m | ∞ | ∞ | 2.15 m |
| 24 mm | 42.4 cm | 1.98 m | ∞ | ∞ | 4.82 m |
| 35 mm | 19.1 cm | 80.0 cm | 6.37 m | 414 m | 10.2 m |
| 50 mm | 9.1 cm | 37.8 cm | 2.52 m | 12.4 m | 20.9 m |
| 85 mm | 3.0 cm | 12.7 cm | 82.2 cm | 3.39 m | 60.3 m |
| 135 mm | 1.1 cm | 4.9 cm | 32.1 cm | 1.30 m | 152 m |
| 200 mm | 0.5 cm | 2.2 cm | 14.4 cm | 58.9 cm | 334 m |
Diffraction at f/4#
Diffraction softening becomes visible at 100% once the Airy disk spans more than about two pixels. It is a gradual effect, not a cliff.
| Sensor | Pixel pitch | Airy disk / pixel | Pixel-level sharpness |
|---|---|---|---|
| Full frame 24 MP | 6.00 µm | 0.9× | no visible loss |
| Full frame 45 MP | 4.39 µm | 1.2× | no visible loss |
| Full frame 61 MP | 3.79 µm | 1.4× | no visible loss |
| APS-C 24 MP | 3.92 µm | 1.4× | no visible loss |
| APS-C 40 MP | 3.04 µm | 1.8× | no visible loss |
| Micro Four Thirds 20 MP | 3.34 µm | 1.6× | no visible loss |
| 1-inch 20 MP | 2.41 µm | 2.2× | slight softening |
| Smartphone 1/1.3" 50 MP | 1.17 µm | 4.6× | diffraction-limited |
f/4 on smaller sensors equals…#
Exposure (brightness) is the same at a given f-number on every format; equivalence describes depth of field and total light.
| Used on | Full-frame equivalent depth of field |
|---|---|
| APS-C (1.5×) | f/6.0 |
| Canon APS-C (1.6×) | f/6.4 |
| Micro Four Thirds (2×) | f/8.0 |
| 1-inch (2.7×) | f/10.8 |
Shutter speed at f/4#
| Light | ISO 100 | ISO 400 | ISO 1600 | ISO 6400 |
|---|---|---|---|---|
| EV 15 · Bright sun, distinct shadows (Sunny 16) | 1/2000 s | 1/8000 s | too bright | too bright |
| EV 13 · Cloudy-bright, no shadows | 1/500 s | 1/2000 s | 1/8000 s | too bright |
| EV 12 · Heavy overcast / open shade | 1/250 s | 1/1000 s | 1/4000 s | too bright |
| EV 10 · Just after sunset | 1/60 s | 1/250 s | 1/1000 s | 1/4000 s |
| EV 8 · Bright interior, city street at night | 1/15 s | 1/60 s | 1/250 s | 1/1000 s |
| EV 5 · Home interior at night | 0.5 s | 1/8 s | 1/30 s | 1/125 s |
| EV 2 · Distant city lights | 4 s | 1 s | 1/4 s | 1/15 s |
| EV -2 · Moonlit landscape | 1 min | 15 s | 4 s | 1 s |
When to use f/4#
f/4 is a go-to setting for portraits with some context, events and indoor sport; most zooms are sharpest a stop down from wide open.
Detailed depth-of-field tables#
Other apertures#
Frequently asked questions#
Is f/4 a wide aperture?
It is a medium aperture. Smaller numbers mean larger openings.
How much light does f/4 let in compared to f/2.8?
0.49× (-1.0 stops).
Last updated October 03, 2026 · How we calculate · Sources