Zone Focusing: The Street Photographer's Secret Weapon
Autofocus is fast, but it isn't instant. In the fraction of a second the camera takes to lock on, the moment can be gone. Zone focusing removes that wait: you set the focus distance and aperture in advance so that a whole range of distances is sharp, then shoot the instant something happens.
How it works
You focus the lens at a fixed distance, say 3 m, and choose an aperture that makes everything from about 2 m to 7 m acceptably sharp. Anything that steps into that range is in focus when you press the button. Nothing is being focused at the time of the shot, depth of field does the work. It is how manual-focus film cameras with distance scales were used for street work, and it still has one real advantage today: the shutter fires the moment your finger moves, with no acquisition time at all.
The numbers
The zone depends on focal length, aperture and the distance you set. These are the useful combinations on full frame:
| Lens and aperture | Focused at | Sharp from | to |
|---|---|---|---|
| 28 mm f/8 | 2 m | 1.3 m | 4.8 m |
| 28 mm f/8 | 3 m | 1.6 m | 24 m |
| 28 mm f/11 | 2.5 m | 1.25 m | infinity |
| 35 mm f/8 | 3 m | 1.9 m | 6.8 m |
| 35 mm f/8 | 4 m | 2.3 m | 16 m |
| 35 mm f/11 | 4 m | 2.0 m | infinity |
| 50 mm f/8 | 3 m | 2.4 m | 4.1 m |
| 50 mm f/8 | 5 m | 3.4 m | 9.2 m |
| 50 mm f/11 | 4 m | 2.7 m | 8.0 m |
Wider lenses give bigger zones. A 28 mm at f/8 focused at 3 m covers nearly any street distance you would want, while a 50 mm at the same settings covers a much narrower band and asks for better judgement of distance. The 28 mm at f/11 focused at 2.5 m is the hyperfocal case, where the far limit reaches infinity.
APS-C and Micro Four Thirds
Compare lenses that frame alike, not the same focal length, and smaller sensors give more depth. An 18 mm lens on APS-C frames like a 28 mm on full frame, and at f/8 focused at 3 m it is sharp from about 1.3 m to infinity, against 1.6 to 24 m for the full-frame 28 mm. A 23 mm on APS-C (like a 35 mm) gives about 1.6 to 20 m, against 1.9 to 6.8 m. If you put a 35 mm lens on APS-C, it frames like a 52 mm and gives about 2.2 to 4.7 m. So zone focusing is more forgiving on smaller sensors when you use the matching wide lens.
Setting up
Switch the lens to manual focus and turn the ring to your chosen distance, using the scale if it has one. If it has no scale, which is common on modern autofocus lenses, autofocus on something at the right distance and then switch to manual to lock it. A small mark of tape or paint pen on the ring helps you set it by feel.
Use f/8 as a default. Go to f/11 for more depth, or f/5.6 when the light is low. Set the shutter to 1/500 s or faster, which freezes a walking person, who moves only about 3 mm in that time. In sun, ISO 200 at f/8 gives about 1/800 s. Overcast, ISO 400 to 800 at f/5.6 and 1/500 s is about right, and at dusk you will be at ISO 1600 to 3200.
Judging distance
You need to know whether a subject is inside your zone, not to the centimetre. Useful markers: an outstretched arm from eye to fist is about 0.7 m, a car is roughly 4.5 m long, and a parking bay about 5 m. With a 35 mm at f/8 focused at 3 m the zone is nearly 5 m deep, so a rough guess is enough. It becomes natural quickly.
Shooting from the hip
Because focus is set, you do not have to look through the viewfinder. Many street photographers shoot with the camera at chest or waist height, which can look less obvious than raising it to the eye. Framing takes practice, so expect many badly framed pictures at first, and a wide lens (28 to 35 mm) gives you room for error. Think about how people react, too. Not being noticed does not make a picture respectful, and laws on photographing people differ between countries. The street photography distance guide covers the human side.
Zone focusing or hyperfocal?
Hyperfocal distance is the zone-focus setting whose far limit reaches infinity, which suits landscapes. For street work it often makes the near limit too far. A 35 mm at f/11 has a hyperfocal distance of 3.9 m, so it is sharp from about 2 m to infinity, which is fine, but a 50 mm at f/8 has a hyperfocal distance of nearly 11 m, so nothing nearer than about 5.4 m is sharp. A zone distance of 2 to 4 m with a 28 to 35 mm lens usually serves better. The hyperfocal distance post has the detail.
Which cameras and lenses
It is easiest with lenses that have a distance scale and a smooth, damped focus ring, which manual-focus lenses and some Fujifilm primes have. Many modern autofocus lenses have a focus-by-wire ring with no scale, which makes setting a distance fiddly, though the autofocus-then-lock method works. Some compact cameras have a snap-focus mode where you set a distance and the camera holds it, the Ricoh GR series being one.
To check any combination before you go, put it into the calculator and read off the near and far limits.
Related reading: Hyperfocal Distance Explained, Shooting Wide Open: When f/1.4 Goes Wrong, Aperture vs Distance: Which Controls DOF More?.