5.02 m
Hyperfocal distance
2.51 m
Sharp from (focused at hyperfocal)
31 mm f/6.1
Full-frame equivalent
70°
Diagonal angle of view
Depth of field by subject distance#
20 mm at f/4 on APS-C (23.5×15.6 mm), circle of confusion 20 µm. “Background blur” is the size of an out-of-focus light at infinity as a percentage of frame width.
| Focus distance | Near limit | Far limit | Total DoF | Front / behind | Background blur |
|---|---|---|---|---|---|
| 30.0 cm (0.98 ft) | 28.4 cm | 31.8 cm | 3.4 cm | 47% / 53% | 1.52% |
| 50.0 cm (1.64 ft) | 45.6 cm | 55.3 cm | 9.7 cm | 45% / 55% | 0.89% |
| 75.0 cm (2.46 ft) | 65.4 cm | 87.8 cm | 22.4 cm | 43% / 57% | 0.58% |
| 1.00 m (3.28 ft) | 83.6 cm | 1.24 m | 40.8 cm | 40% / 60% | 0.43% |
| 1.50 m (4.92 ft) | 1.16 m | 2.13 m | 97.3 cm | 35% / 65% | 0.29% |
| 2.00 m (6.56 ft) | 1.43 m | 3.31 m | 1.88 m | 30% / 70% | 0.21% |
| 3.00 m (9.84 ft) | 1.88 m | 7.43 m | 5.55 m | 20% / 80% | 0.14% |
| 4.00 m (13.1 ft) | 2.23 m | 19.6 m | 17.4 m | 10% / 90% | 0.11% |
| 5.00 m (16.4 ft) | 2.51 m | 1.3 km | 1.2 km | 0% / 100% | 0.09% |
| 7.00 m (23.0 ft) | 2.92 m | ∞ | ∞ | — | 0.06% |
| 10.0 m (32.8 ft) | 3.34 m | ∞ | ∞ | — | 0.04% |
| 15.0 m (49.2 ft) | 3.75 m | ∞ | ∞ | — | 0.03% |
| 20.0 m (65.6 ft) | 4.00 m | ∞ | ∞ | — | 0.02% |
| 30.0 m (98.4 ft) | 4.29 m | ∞ | ∞ | — | 0.01% |
| 50.0 m (164 ft) | 4.55 m | ∞ | ∞ | — | 0.01% |
| 100 m (328 ft) | 4.76 m | ∞ | ∞ | — | 0.00% |
Try other settings#
Near limit—
Far limit—
Depth of field—
Hyperfocal distance—
In front / behind—
20 mm at other apertures (subject at 3 m)#
Other focal lengths at f/4#
| Focal length | Subject at | Total DoF |
|---|---|---|
| 14 mm | 3.00 m | ∞ |
| 16 mm | 3.00 m | 42.9 m |
| 20 mm | 3.00 m | 5.55 m |
| 24 mm | 3.00 m | 2.99 m |
| 28 mm | 3.00 m | 2.00 m |
| 35 mm | 3.00 m | 1.21 m |
| 40 mm | 3.00 m | 90.8 cm |
| 50 mm | 3.00 m | 57.1 cm |
| 85 mm | 3.00 m | 19.4 cm |
| 105 mm | 3.00 m | 12.6 cm |
| 135 mm | 3.00 m | 7.5 cm |
| 200 mm | 10.0 m | 39.2 cm |
| 300 mm | 10.0 m | 17.2 cm |
| 400 mm | 10.0 m | 9.6 cm |
| 600 mm | 10.0 m | 4.2 cm |
Same lens settings on other formats#
When to use it#
At f/4, a 20 mm lens on APS-C is a natural choice for general photography. Focused at 3 m you get 5.55 m of sharp zone; for maximum front-to-back sharpness focus at 5.02 m and everything from 2.51 m to infinity will be acceptably sharp.
See also the f/4 aperture guide.
Frequently asked questions#
What is the depth of field of a 20mm lens at f/4?
On APS-C, focused at 3 m, it is 5.55 m; at 1 m it is 40.8 cm.
What is the hyperfocal distance for 20mm f/4?
5.02 m (16.5 ft) on APS-C. Everything from 2.51 m to infinity is acceptably sharp.
Last updated October 03, 2026 · How we calculate · Sources