Bokeh, the quality of blur.
Bokeh is often mistakenly taken to mean the blur or the amount of blur in an image produced when objects are captured when outside the depth of field, the area producing an acceptable sharpness, whereas technically it actually means the quality of the blur itself, not the amount.
Bokeh comes from the Japanese word boke (ボケ) meaning “blur” or “haze” and translates as the quality of the blur, and according to Wikipedia is . . . the aesthetic quality of the blur produced in the out-of-focus parts of an image produced by a lens.
And for this reason there is both “good” and “bad” bokeh.
Depth of field
A popular effect with outdoor portraiture is to use a very shallow depth of field when photographing the subject, because the shallow depth of field ensures that the subject is visually isolated from an indistinguishable background, because the subject remains sharply in focus, whereas everything outside of the depth of field is out of focus, including especially the background, not forgetting that the background is then not quite so critical and is therefore no longer an active and distracting element in the composition.
The depth of field is a physical effect of light passing through the aperture, a large aperture will produce a very narrow depth of field whereby only the subject remains in focus, everything else quickly blurring out, whereas a very small aperture will produce a very large depth of field, whereby almost everything from the foreground to the background remains in focus, thus producing no bokeh, good or bad.
But not all lenses are built equally, the quality of the blur that the lens produces of the out of focus parts of the image can be dramatically quite different depending on the lens used, because some lenses produce “good” bokeh, and others “bad” bokeh, it’s all down to the optical design of the lens itself.
But generally a good prime lens with a large maximum aperture will produce a pleasing bokeh, soft and creamy with smooth round edges, whereas a cheap consumer lens will tend to produce one with sharp multiple edges.
Bokeh therefore, in the purest sense, can’t be practiced, it can only be paid for with the investment in a high quality lens.
But setting that aside for a moment, it’s still very rewarding to take photographs whereby the backgrounds are out of focus and distant lights are captured as aesthetically pleasing soft pools of colour.
And so although it’s a lot easier with a good, expensive lens, it’s still possible to practice with a cheap consumer lens, even though the quality of the bokeh won’t be quite so perfect.
And using a wide aperture isn’t the only method of creating a relatively shallow depth of field, it’s also possible to create the right conditions by either decreasing the distance between the camera and the subject, or increasing the distance between the subject and the background, preferably by doing both.
Some examples illustrating the technique
Tips for when on location
- Set the camera to A-mode, aperture priority, and set the aperture to the widest possible to ensure a shallow depth of field.
- Get as close to the subject with the camera as possible, as this also shortens the depth of field.
- Find a colourful background preferably with lights in it, Xmas is the perfect time to practice this because of the dark evenings and the multitude of small distant lights everywhere.
© Andrew James Kirkwood – 2017