The Casual Film Lover’s Guide to the Bokeh Effect

Welcome to How’d They Do That? — a monthly column that unpacks moments of movie magic and celebrates the technical wizards who pulled them off. This entry explains how cinematographers achieve the optical byproduct known as the bokeh effect.

If your main relationship with movies is as an audience member, the more technical aspects of film cameras might be a bit intimidating. Between focal ratios and lumen metering, it’s easy to get lost. I’m pretty sure there’s a circle of confusion joke in there somewhere.

As I’ve mentioned previously in this column, cinematography exists somewhere in the middle of the proverbial Venn Diagram of “science vs. art.” Shooting movies is a creative discipline, obviously. But there’s also a fair degree of optical physics involved — and that can be overwhelming if your wheelhouse lies elsewhere.

Personally speaking, the only way photographic principles make sense to my smooth non-applied-science brain is to see them on the big screen first and work my way backward. There’s something special about learning how the sausage is made. And for most folks, I’d imagine the inquisitive gesture isn’t too dissimilar: you see something neat, you get curious, and you look for answers. Generally speaking, the internet was a mistake. But being able to dig into the nitty-gritty of an art form you love is pretty special.

The bokeh effect

Even if you’ve never heard the word “bokeh” before, I can almost guarantee that you’ve already seen it on-screen hundreds if not thousands of times. As I’ll mention a bit further down in this article, bokeh’s power largely involves working away in the background, not drawing attention to itself, and bolstering a look and a mood that have an immense impact on the “feel” of a given shot. So, if you’re enchanted by that painterly blur — or by those fuzzy soap bubble-like circles of light that pop up every now and then — here’s your first step to understanding how the bokeh effect works:

How’d they do that?

Long story short:

The bokeh effect describes the intentional exaggeration of out-of-focus elements in a shot. It is created when the foreground and/or background of a frame is intentionally blurred around the subject. Variations in camera lenses (aberrations, aperture, etc.) govern the aesthetic characteristics of bokeh.

Long story long:

First things first: why is the effect called “bokeh” in the first place? The term originates from the Japanese word ボケ (boke), which literally translates to “blur” or “haze.” Bokeh is typically pronounced BOH-Kə or BOH-kay. And if any anglophones tease you for getting it wrong you have my permission to tell them to suck eggs. Bokeh’s modified English spelling was first popularized in the Spring 1997 issue of Photo Techniques magazine, which contained three papers on the topic.

Generally speaking, when people talk about bokeh, they are referring to one of two things. (1) A pleasing aesthetic type of blur that is produced in the out-of-focus areas of an image. And/or (2), recognizable lens aberrations that produce bubbles of colored light or starburst shapes in the out-of-focus regions. So, it’s worth noting: those iconic little colored circles aren’t the only thing that’s bokeh. Anything outside the depth of field counts.

Bokeh describes a specific character or quality of out-of-focus blur. It isn’t about how much blur there is or whether there is a blur, but rather what the blur looks and feels like. This can be subjective!

Shallow focus techniques, like longer focal lengths and reduced depth of field, are key in increasing the out-of-focus space in a shot and accentuating the bokeh effect. Another trick is to position the subject close to a fast lens at the widest aperture. The closer you move the camera to the subject, the shallower your depth of field and the blurrier your background will be. Additionally, it’s ideal for the subject to be super far from background elements to exaggerate the effect of them being sharp and distinct and everything else being fuzzy.

Because the effect is subjective there is “good” and “bad” bokeh. Bad bokeh is often described as being “crunchy,” overexposed, or featuring a subject that has been caught up in the blur. Good bokeh, meanwhile, is characterized by the presence of a clear, well-defined subject set against a soft, creamy background often sprinkled with fuzzy punctuations of light. When assessing whether bokeh is pleasing or not (you know, that thing we all do when we have friends over for dinner), it’s helpful to distinguish the quality of “soap bubble” light reflections and the quality of the entire out-of-focus area.

Unlike more encompassing terms like background blur or soft focus, bokeh is a property of lenses rather than wholesale images. And because bokeh is rendered by a lens (and not a camera), different lenses render bokeh differently. Case and point: those iconic little soap bubbles that most people associate with bokeh.

When bokeh manifests as fuzzy colored circles what you’re seeing is an image of the camera’s aperture. Every lens has blades on its diaphragm that open and close, creating the aperture. The number of blades on a lens’ diaphragm will determine the shape of the bokeh. Fewer blades will create more angular bokeh whereas more blades will create rounder-looking bokeh. So to summarize: the lens diaphragm affects the way that the reflected light in out-of-focus areas will look. This is probably a good time to mention that you can’t achieve the bokeh effect without distinct light sources (e.g. sunlight streaming through trees, Christmas lights, candles, etc.). There must be a distinction between light and dark areas in the background for bokeh to occur.

The narrative power of bokeh

On the one hand, I’m sure some cinematographers simply use bokeh because it looks neat. Liking the way a dynamic balance between soft and sharp images looks doesn’t need any further justification. But for the sake of giving credit where credit’s due, let’s run down a couple of the more intention-rich reasons filmmakers might want to incorporate bokeh into their shots.

Like any element of film craft, bokeh is a tool that can accomplish a variety of subjective effects depending on the context of how it’s deployed. In Wes Anderson’s The Grand Budapest Hotel, the romantic qualities of the bokeh effect are on full display when Agatha’s warm smile radiates in the afterglow of the swirling, soft circles of the carousel.

There’s also a strong case to be made that the bokeh effect endows shots with a distinctly dreamlike quality; a dissolving abstraction that emulates the feeling of drifting off into something that is both murky and attentive. Is it a coincidence, in Eyes Wide Shut, that sleepy-eyed Dr. Bill is bathed in half-formed Christmas lights when he first learns of the secretive high society sex cult? Or that the limbo-like Djibouti club where Galoup dances himself clean in Beau Travail is flecked with rosy spheres?

On the other end of the spectrum, bokeh can also be used to create a claustrophobic sense of hyperfocus. As Benjamin B. writes for American Society of Cinematographers magazine, the Safdie brothers’ 2019 film Uncut Gems offers a convincing argument that “the personality and the emotion of a lens resides mostly in the out-of-focus bokeh, which, like perfume, is not visible … we perceive the feeling of the bokeh, but we don’t really pay attention to it.”

Indeed, in the capable hands of Uncut Gems’ DP Darius Khondji, bokeh takes on a painterly quality. “Almost like a rear screen projection,” Khondji explains. Continuing, Khondji emphasizes another intention behind his exaggerated use of bokeh was to isolate characters; to place all the focus on them, and reduce the rest of the world to swirling chaos. Quiet though it may be, bokeh is one of the key reasons Uncut Gems resonates as a resolute modern entry in “anxiety cinema.”

I’ve left the strangest use of bokeh for last. In recent years, a certain animation studio (which may or may not rhyme with “Bixar”) has made a concerted effort to train their virtual cameras to behave like real ones. A virtual camera doesn’t organically produce bokeh (duh) because it doesn’t have a physical lens. But through emulation of real-life optical elements (depth of field, lens flares, etc.), films like Soul and Toy Story 4 are able to draw upon the emotional and aesthetic characteristics of real-life cinematographic choices like bokeh.

While bokeh doesn’t always arise out of strong-willed aesthetic intention, it is, nevertheless, another piece of the visual storytelling Jenga tower. So it makes sense that animation directors would be interested in teaching their virtual cameras to imitate their physical counterparts. Because while bokeh might literally fade into the background, quite literally, the effect is a powerful tool at a DP’s disposal. Be on the lookout for it. And ask yourself if the bokeh you spot is doing anything more than making frames look especially pretty.