13.4 m
Hyperfocal distance
6.69 m
Sharp from (focused at hyperfocal)
40 mm f/4.0
Full-frame equivalent
57°
Diagonal angle of view
Depth of field by subject distance#
40 mm at f/4 on full frame (36×24 mm), circle of confusion 30 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) | 29.4 cm | 30.6 cm | 1.2 cm | 49% / 51% | 4.27% |
| 50.0 cm (1.64 ft) | 48.3 cm | 51.8 cm | 3.5 cm | 48% / 52% | 2.42% |
| 75.0 cm (2.46 ft) | 71.2 cm | 79.2 cm | 8.0 cm | 47% / 53% | 1.56% |
| 1.00 m (3.28 ft) | 93.3 cm | 1.08 m | 14.5 cm | 46% / 54% | 1.16% |
| 1.50 m (4.92 ft) | 1.35 m | 1.68 m | 33.2 cm | 45% / 55% | 0.76% |
| 2.00 m (6.56 ft) | 1.74 m | 2.34 m | 60.1 cm | 43% / 57% | 0.57% |
| 3.00 m (9.84 ft) | 2.45 m | 3.86 m | 1.40 m | 39% / 61% | 0.38% |
| 4.00 m (13.1 ft) | 3.08 m | 5.69 m | 2.61 m | 35% / 65% | 0.28% |
| 5.00 m (16.4 ft) | 3.64 m | 7.96 m | 4.32 m | 31% / 69% | 0.22% |
| 7.00 m (23.0 ft) | 4.60 m | 14.6 m | 10.0 m | 24% / 76% | 0.16% |
| 10.0 m (32.8 ft) | 5.72 m | 39.5 m | 33.8 m | 13% / 87% | 0.11% |
| 15.0 m (49.2 ft) | 7.07 m | ∞ | ∞ | — | 0.07% |
| 20.0 m (65.6 ft) | 8.01 m | ∞ | ∞ | — | 0.06% |
| 30.0 m (98.4 ft) | 9.24 m | ∞ | ∞ | — | 0.04% |
| 50.0 m (164 ft) | 10.5 m | ∞ | ∞ | — | 0.02% |
| 100 m (328 ft) | 11.8 m | ∞ | ∞ | — | 0.01% |
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 | ∞ |
| 20 mm | 3.00 m | 26.7 m |
| 24 mm | 3.00 m | 6.04 m |
| 28 mm | 3.00 m | 3.44 m |
| 35 mm | 3.00 m | 1.90 m |
| 40 mm | 3.00 m | 1.40 m |
| 50 mm | 3.00 m | 86.7 cm |
| 85 mm | 3.00 m | 29.1 cm |
| 105 mm | 3.00 m | 18.9 cm |
| 135 mm | 3.00 m | 11.3 cm |
| 200 mm | 10.0 m | 58.9 cm |
| 300 mm | 10.0 m | 25.9 cm |
| 400 mm | 10.0 m | 14.4 cm |
| 600 mm | 10.0 m | 6.3 cm |
Same lens settings on other formats#
When to use it#
At f/4, a 40 mm lens on full frame is a natural choice for general photography. Focused at 3 m you get 1.40 m of sharp zone; for maximum front-to-back sharpness focus at 13.4 m and everything from 6.69 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 full frame, focused at 3 m, it is 1.40 m; at 1 m it is 14.5 cm.
What is the hyperfocal distance for 40mm f/4?
13.4 m (43.9 ft) on full frame. Everything from 6.69 m to infinity is acceptably sharp.
Last updated October 03, 2026 · How we calculate · Sources