f/9
Aperture
6.3
Stops less light than f/1
1.23%
Light vs f/1
2.13 m
DoF: 50 mm at 3 m (FF)
12.1 µm
Airy disk diameter
Depth of field at f/9 (full frame)#
| Focal | at 1 m | at 2 m | at 5 m | at 10 m | Hyperfocal |
|---|---|---|---|---|---|
| 16 mm | ∞ | ∞ | ∞ | ∞ | 96.4 cm |
| 24 mm | 1.16 m | 26.1 m | ∞ | ∞ | 2.16 m |
| 35 mm | 44.6 cm | 2.13 m | ∞ | ∞ | 4.57 m |
| 50 mm | 20.7 cm | 88.1 cm | 7.49 m | ∞ | 9.31 m |
| 85 mm | 6.8 cm | 28.8 cm | 1.90 m | 8.59 m | 26.8 m |
| 135 mm | 2.6 cm | 11.1 cm | 72.5 cm | 2.99 m | 67.6 m |
| 200 mm | 1.1 cm | 4.9 cm | 32.4 cm | 1.33 m | 148 m |
Diffraction at f/9#
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 | 2.0× | slight softening |
| Full frame 45 MP | 4.39 µm | 2.7× | slight softening |
| Full frame 61 MP | 3.79 µm | 3.2× | slight softening |
| APS-C 24 MP | 3.92 µm | 3.1× | slight softening |
| APS-C 40 MP | 3.04 µm | 4.0× | diffraction-limited |
| Micro Four Thirds 20 MP | 3.34 µm | 3.6× | diffraction-limited |
| 1-inch 20 MP | 2.41 µm | 5.0× | diffraction-limited |
| Smartphone 1/1.3" 50 MP | 1.17 µm | 10.3× | diffraction-limited |
f/9 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/13.5 |
| Canon APS-C (1.6×) | f/14.4 |
| Micro Four Thirds (2×) | f/18.0 |
| 1-inch (2.7×) | f/24.3 |
Shutter speed at f/9#
| Light | ISO 100 | ISO 400 | ISO 1600 | ISO 6400 |
|---|---|---|---|---|
| EV 15 · Bright sun, distinct shadows (Sunny 16) | 1/400 s | 1/1600 s | 1/6400 s | too bright |
| EV 13 · Cloudy-bright, no shadows | 1/100 s | 1/400 s | 1/1600 s | 1/6400 s |
| EV 12 · Heavy overcast / open shade | 1/50 s | 1/200 s | 1/800 s | 1/3200 s |
| EV 10 · Just after sunset | 1/13 s | 1/50 s | 1/200 s | 1/800 s |
| EV 8 · Bright interior, city street at night | 0.3 s | 1/13 s | 1/50 s | 1/200 s |
| EV 5 · Home interior at night | 2.5 s | 0.6 s | 1/6 s | 1/25 s |
| EV 2 · Distant city lights | 20 s | 5 s | 1.3 s | 0.3 s |
| EV -2 · Moonlit landscape | > 4 min | 1 min | 20 s | 5 s |
When to use f/9#
f/9 is a go-to setting for landscapes and architecture needing front-to-back sharpness on full frame, and sunstars.
Other apertures#
Frequently asked questions#
Is f/9 a wide aperture?
No — f/9 is a small (narrow) aperture. Smaller numbers mean larger openings.
How much light does f/9 let in compared to f/2.8?
0.10× (-3.4 stops).
Last updated October 03, 2026 · How we calculate · Sources