How the simulation works
The camera stands on a path at a height of 1.5 metres and focuses on the person, who is 1.75 metres tall. Markers on the ground show the distance. From focal length, aperture, sensor size and focus distance, the simulator computes for every point in the scene how large its blur circle is in the picture and softens it accordingly. The further something is in front of or behind the person, the more it blurs. The numbers next to the view use the same formulas.
What affects depth of field?
Four values decide how much of the picture is sharp: the aperture, the focal length, the distance to the subject and the sensor size. A wider aperture (smaller f-number), a longer focal length and a shorter distance all make the depth of field shallower. A smaller sensor gives more depth of field with the same angle of view and f-number, which is why full frame at f/2.8 blurs the background about as much as APS-C at f/1.8. The equivalent value in the result shows this conversion.
How to calculate depth of field
The hyperfocal distance H follows from the focal length f, the f-number N and the circle of confusion c, the largest blur that still looks sharp. This page uses c = sensor diagonal ÷ 1500, about 0.029 mm on full frame and 0.019 mm on APS-C. From H and the focus distance s you get the near and far limits of the sharp zone. If you focus at the hyperfocal distance, everything from half that distance to infinity is acceptably sharp.
H = f² ÷ (N × c) + f
Near limit = s × (H − f) ÷ (H + s − 2f)
Far limit = s × (H − f) ÷ (H − s)
Depth of field table
The sharp zone from near to far limit on full frame with the subject at 3 metres, for common focal lengths and apertures.
| Focal length | f/1.4 | f/2.8 | f/5.6 | f/11 |
|---|---|---|---|---|
| 24 mm | 2.48 m to 3.79 m | 2.12 m to 5.15 m | 1.64 m to 18.13 m | 1.14 m to ∞ |
| 35 mm | 2.73 m to 3.32 m | 2.51 m to 3.73 m | 2.16 m to 4.93 m | 1.7 m to 12.93 m |
| 50 mm | 2.86 m to 3.15 m | 2.74 m to 3.32 m | 2.52 m to 3.71 m | 2.18 m to 4.8 m |
| 85 mm | 2.95 m to 3.05 m | 2.91 m to 3.1 m | 2.82 m to 3.21 m | 2.66 m to 3.44 m |
| 135 mm | 2.98 m to 3.02 m | 2.96 m to 3.04 m | 2.93 m to 3.08 m | 2.86 m to 3.16 m |
What the simulation does not show
The scene is a model, not a photo taken with a real lens. It shows how strongly the background blurs, but not the bokeh character of a particular lens: the shape of out of focus highlights, onion rings, cat's eye bokeh or swirl. Vignetting, distortion, sharpness and focus breathing are not simulated either, and many lenses change their angle of view slightly at close range. For those, look at sample photos and the manufacturer's data.
Frequently asked questions
What is depth of field?
Depth of field is the zone in front of and behind the focus point that looks acceptably sharp in the picture. Strictly speaking only one plane is in focus. How far the sharp zone reaches depends on how much blur still looks sharp at a normal viewing size.
How do I get a blurred background?
Open the aperture as far as your lens allows, use a longer focal length, get closer to your subject and leave plenty of distance between subject and background. In the simulator you can try each of these and see how the blur changes.
Does a crop sensor give more depth of field?
With the same angle of view and the same f-number, yes. To get the same frame on APS-C you use a shorter focal length or stand further away, and both increase depth of field. To compare, multiply the f-number by the crop factor: f/1.8 on APS-C gives about the depth of field of f/2.8 on full frame. The exposure does not change, f/1.8 stays f/1.8 for brightness.
What is the hyperfocal distance?
It is the focus distance at which the depth of field just reaches infinity. Focus there and everything from half that distance to infinity looks sharp, which is useful for landscapes. A 24 mm lens on full frame at f/8 has a hyperfocal distance of about 2.5 metres.
Why can't I choose every aperture?
When you pick a lens, the simulator only offers apertures that lens can actually use, from its maximum to its minimum aperture as listed in our database. On zooms whose maximum aperture changes over the zoom range, the limit follows the focal length. Without a lens you can choose any common f-number.