20.0 m
Hyperfocal distance
10.0 m
Sharp from (focused at hyperfocal)
61 mm f/6.1
Full-frame equivalent
39°
Diagonal angle of view
Depth of field by subject distance#
40 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) | 29.6 cm | 30.4 cm | 0.8 cm | 49% / 51% | 6.55% |
| 50.0 cm (1.64 ft) | 48.9 cm | 51.2 cm | 2.3 cm | 49% / 51% | 3.70% |
| 75.0 cm (2.46 ft) | 72.4 cm | 77.8 cm | 5.3 cm | 48% / 52% | 2.40% |
| 1.00 m (3.28 ft) | 95.4 cm | 1.05 m | 9.6 cm | 48% / 52% | 1.77% |
| 1.50 m (4.92 ft) | 1.40 m | 1.62 m | 22.0 cm | 46% / 54% | 1.17% |
| 2.00 m (6.56 ft) | 1.82 m | 2.22 m | 39.6 cm | 45% / 55% | 0.87% |
| 3.00 m (9.84 ft) | 2.61 m | 3.52 m | 90.8 cm | 43% / 57% | 0.58% |
| 4.00 m (13.1 ft) | 3.34 m | 4.99 m | 1.65 m | 40% / 60% | 0.43% |
| 5.00 m (16.4 ft) | 4.01 m | 6.65 m | 2.64 m | 38% / 62% | 0.34% |
| 7.00 m (23.0 ft) | 5.19 m | 10.7 m | 5.54 m | 33% / 67% | 0.24% |
| 10.0 m (32.8 ft) | 6.68 m | 19.9 m | 13.2 m | 25% / 75% | 0.17% |
| 15.0 m (49.2 ft) | 8.58 m | 59.5 m | 50.9 m | 13% / 87% | 0.11% |
| 20.0 m (65.6 ft) | 10.0 m | 10.0 km | 10.0 km | 0% / 100% | 0.09% |
| 30.0 m (98.4 ft) | 12.0 m | ∞ | ∞ | — | 0.06% |
| 50.0 m (164 ft) | 14.3 m | ∞ | ∞ | — | 0.03% |
| 100 m (328 ft) | 16.7 m | ∞ | ∞ | — | 0.02% |
Try other settings#
Near limit—
Far limit—
Depth of field—
Hyperfocal distance—
In front / behind—
40 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 40 mm lens on APS-C is a natural choice for general photography. Focused at 3 m you get 90.8 cm of sharp zone; for maximum front-to-back sharpness focus at 20.0 m and everything from 10.0 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 40mm lens at f/4?
On APS-C, focused at 3 m, it is 90.8 cm; at 1 m it is 9.6 cm.
What is the hyperfocal distance for 40mm f/4?
20.0 m (65.7 ft) on APS-C. Everything from 10.0 m to infinity is acceptably sharp.
Last updated October 03, 2026 · How we calculate · Sources