POR · Portrait
Shallow Depth of Field Portraits: Aperture, Distance, Eye Focus
Creamy background blur comes from three controls, and distance matters more than aperture. Here is how to get eyes tack sharp while the background melts away.
Diagrams
Depth of field is controlled by three things: aperture, distance to the subject, and focal length — and distance matters most. With an 85mm lens at f/1.8 and your subject three metres away, the zone of sharp focus is only a few centimetres deep. Move to one metre and it shrinks to millimetres; step back to five metres and you get a usable band across the face. That is why the same lens feels unusable in a small room and beautiful on the street. If you cannot get far enough back, a longer focal length at the same framing blurs the background more than a wider lens does.
Focus technique decides whether the shot survives. Switch to single-point AF — or eye autofocus if your camera has it — and place the point on the eye nearest the camera. Focus-and-recompose fails at f/1.4 because the plane of focus swings as you rotate the camera, leaving the far eye sharp and the near eye soft. Instead, move the AF point with the joystick, or use back-button focus so a half-press of the shutter does not re-trigger focus. Then shoot three or four frames: people sway forward and back by a centimetre or two, which is enough to miss at wide apertures.
Aperture is a creative choice, not a contest. f/1.2 to f/2 gives the strongest separation but risks one eye sharp and the other soft; in a three-quarter view that is often charming, in a frontal headshot it usually looks like a mistake. f/2.8 to f/4 is the safe portrait range: the whole face holds detail and the background stays soft. Save f/1.4 for when the background is genuinely ugly.
Background distance does half the work. A subject standing one metre from a wall will never blur much, no matter the aperture; move them three or four metres from the background and the same settings turn it to butter.
Common mistakes: shooting wide open against a wall, judging sharpness on the camera LCD instead of zooming to 100 percent, and chasing blur so hard that both eyes go soft. A sharp eye beats a blurry background every time.
Key points
- Distance to the subject changes depth of field more than aperture does — step back before you stop down.
- Use single-point AF or eye autofocus on the near eye; avoid focus-and-recompose at f/1.4.
- f/2.8 to f/4 keeps the whole face sharp while the background stays soft — the safe portrait range.
- Move your subject three to four metres from the background; distance blurs it more than aperture alone.
