So, “bokeh”: that's a Japanese word that has no English equivalent, but once explained a very simple concept for any camera-wielder to grasp.
How simple? Well, this five-step guide will clue you in on all the blurry basics.
There is both “good” and “bad” bokeh
Each lens’ characteristics – namely lens aberration and the shape of its aperture – determine the sort of bokeh it creates. Curved aperture blades, for instance, help create bokeh that looks more circular and, to most eyes, more pleasing – there are even lenses like Sony’s STF 135mm F2.8 and Nikon’s 105mm DC-Nikkor that are designed specifically to produce beautiful, buttery-smooth bokeh. Using a lens with fewer or straighter aperture blades can result in bokeh that’s more angular and “ugly”.
Image credit: Jerome Marot
The wider the aperture, the more likely you are to get bokeh
Bokeh occurs when portions of the image are in front of or behind the in-focus area. The easiest way to achieve this shallow depth of field is to use a lens with a wide aperture like F1.8, F2.0 or F2.8. Alternatively, you can use a longer, lower aperture lens – let’s say an 18-55mm kit zoom set at 55mm and F5.6 – and ensure a good amount of distance between the subject and the background.
Compacts and smartphones can achieve bokeh – but it’s tough
Because of their tiny apertures, it’s difficult to get bokeh in shots taken with point-and-shoot and smartphone cameras. The only way to achieve “real” bokeh with such cameras is to take a macro photo (a shot of something very close to the lens), which will likely result in a blurry background and sharp, in-focus subject.
Image credit: Intensivtäteraggressor
There are some software tricks, however…
Many small cameras can use technical trickery to create fake bokeh. Google's Camera app, for instance, uses a clever algorithm to simulate bokeh, but requires that everything in the frame remain still for a few seconds. Most of these techniques can’t match the effect of real bokeh, but can deliver decent results in a pinch.