Short answer: Bokeh is the aesthetic quality of the unfocused part of an image. Another term for this is lens blur.
What does bokeh mean?
Bokeh is used to reference the out of focus part of an image and the aesthetic quality of that part of the image. With this in mind, you might not like the bokeh in a photo and called it bad bokeh. Or, as will more often be the case, you’ll mention bokeh because you like the quality produced.
Bokeh is most commonly mentioned when circles of light are present in the image. These are commonly called bokeh circles or bokeh balls. Bokeh circles will most often be present in night time shots, as in the photo above, but can also be present in day time shots:
What are bokeh circles?
When a point of light is out of focus this is rendered as a larger ball of light by your camera lens. This is what we mostly think about when we think of bokeh. If you type bokeh into Google, this is present in most of the images you see.
How does aperture affect bokeh?
A large aperture, f/2 for example, will create more background blur, a more obvious bokeh and larger bokeh circles. As you narrow your aperture, by increasing your f-stop, the out of focus portion of your image starts to become clearer, the bokeh will be less noticeable and with smaller bokeh circles.
There is no right way of course, it’s all about your preference and the look you wish to achieve. Typically though when a photographer wants background blur, for instance in a portrait, and very noticeable bokeh they will use a fast lens, for example on that can shoot at f/1.4, and will have the aperture wide open.
Where does the term bokeh come from?
Bokeh is derived from a few Japanese words that are used to describe related concepts like blur, mental haze and playing dumb, in nuanced ways. Find out more in Wikipedia’s Origin section.
The English spelling “bokeh” was popularised in a 1997 issue of Photo Techniques. In an article called What Is ‘Bokeh’? by John Kennerdell.
Resource: The Online Photographer
How do you pronounce bokeh?
The most common pronunciations I’ve heard are bo (like bow) and ka, bo–ka. Or bo–kay, like bouquet. Or bo–keh, with the Ke sound from a word like Kenneth.
To add to the confusion to the issue here’s a video from Photogearnews to show how many pronunciations people will use:
If it helps, I say bo–ka but that’s just easier for me to say.
How to take a bokeh effect photo
Taking a photo with bokeh is as simple as taking a photo that’s completely out of focus, or has an out of focus part.
To create noticeable bokeh use a low f-stop on your lens so that the depth-of-field is shallow. Then ensure there is distance between your subject and the background, experiment with this to get the effect you want.
How to create different bokeh ball shapes
The shape of the bokeh circle is defined by the shape of the opening on the lens. This is why bokeh circles can have edges, the edges come from the aperture blades. The smaller your aperture, the greater the effect of the blades on the shape of the bokeh circle. This is because the blades are more closed in. There are lenses specifically designed to create rounder bokeh with more circular aperture blades.
In the below image you can see the bokeh circles have edges caused by the aperture blades:
You can dramatically change the shape of the bokeh circle by placing a piece of card with a shape cut out in front of your lens. This is how you can create bokeh circles in heart shapes, stars, or anything you like. Check out this tutorial from Christopher Frost on YouTube for a demonstration of this:
What creates textures in bokeh balls?
This can be dust and particles on your lens, so if you want a smooth effect then make sure your lens and sensor are as clean as possible. But this can also be a quality of the lens itself, which you won’t be able to get rid of. This is another reason why some lenses are designed specifically for bokeh effect, e.g. the smooth effect and round bokeh circles that most people would consider desirable.
How do you get swirly bokeh?
This is created by the lens, typically a vintage or lomography lens. For example, the below image was taken with a vintage lens, Helios 44M-2 58mm, to get the swirly effect. This lens in particular is popular for this effect.
In-Depth Bokeh Video
A great video from Tony & Chelsea Northup on YouTube: