What is Bokeh?

Columbine at the Huntington Library gardens, shot at f/4.5 to throw the background into bokeh. © John Corney

A photograph I took of columbines at the Huntington Library gardens recently has such a beautiful bokeh effect that I thought I'd use it as an excuse to talk about bokeh today — what it is, where the word comes from, and how to get it in your own photographs.

What Bokeh Actually Is

The word bokeh comes from the Japanese word boke (暈け), meaning "blurred" or "haze." It started being used by photographers in the late 1990s to describe specifically the quality of the out-of-focus areas of a photograph — not just the fact that the background is blurred, but how aesthetically the blurring is rendered. Good bokeh is creamy, smooth, and pleasing. Bad bokeh is harsh, distracting, or busy. Two lenses can produce the same depth of field but very different bokeh.

It's pronounced roughly "BOH-keh" — like the "bo" in bone, and the "ke" as in Ken, with the stress fairly even across both syllables. (English speakers sometimes say "BOH-kay," which has crept into common usage, though it isn't quite faithful to the Japanese.)

How Bokeh Is Made

Three things contribute to the bokeh in any photograph: the lens, the aperture setting, and what's actually in the background.

I took the photo above with a Canon EF 24-105mm f/4L lens at 105mm, with the aperture wide open at f/4.5. That wide aperture is the first ingredient — it produces a shallow depth of field, meaning only a thin slice of the scene is in focus, and everything in front of and behind that slice is blurred.

If you're near-sighted, like me, here's an analogy that makes shallow depth of field easy to feel. Looking at a close-up object with your eyes open is roughly your eye's "wide aperture" — the object is sharp, but everything in the distance is blurred. To see the distance more clearly without your glasses, what do you do? You squint. That narrows your pupil, the iris's aperture — and suddenly more of the world comes into focus at once. The same thing happens with a camera lens: open the aperture (low f-number, like f/2.8 or f/4) for a shallow depth of field with creamy background blur, or close it down (high f-number, like f/11 or f/16) for "deep depth of field" where everything is sharp.

The lens itself matters too. The Canon 24-105mm f/4L is a high-quality "L-series" lens, and it renders bokeh beautifully. Less expensive zoom lenses I own don't produce bokeh anywhere near as appealing, even at the same aperture and focal length. The shape and number of aperture blades, the lens's optical design, and the quality of the glass all contribute. As a general rule, fast prime lenses (those with maximum apertures of f/1.4, f/1.8, or f/2.8) and high-end professional zooms tend to produce the most pleasing bokeh — which is one of several reasons photographers pay a premium for them.

The third ingredient is the background itself. Bokeh shows itself most beautifully when the out-of-focus area contains highlights — small bright points of light, dappled sun through leaves, droplets of water, reflective surfaces. Those become the soft glowing circles or hexagons known as "bokeh balls." Their shape, incidentally, comes from the lens's aperture blades: a lens with rounded blades produces circular bokeh balls, while one with straight blades produces polygonal ones. The same scene through two different lenses can produce noticeably different visual personalities.

Try It Yourself

If you'd like to play with bokeh, the recipe is straightforward: set your camera to a low f-stop (wide aperture), choose a subject with a background that's well behind it — ideally with some light on it — and see what you can come up with. Flowers, with a sunlit garden behind them, are an obvious and very forgiving starting point.

And if you don't have a DSLR or a mirrorless camera with interchangeable lenses, take heart: modern smartphones do a remarkably good job of simulating bokeh in their "Portrait" or "Cinematic" modes. They do it computationally rather than optically — using software to detect the subject and synthetically blur everything else — and the results aren't quite as natural as a real lens at f/2.8, but they're often genuinely beautiful and getting better with each generation. The principles are the same: get close to your subject, keep the background well behind, look for highlights in that background. The rest is light and luck.