If you’ve ever been on a photography blog, chances are you’ve heard photographers arguing about which lens produces the best bokeh. Bokeh comes from the Japanese word boke, meaning blur or haze.
Bokeh describes the quality of out of focus areas in a photograph. It is not how far out of focus something is, but rather the appearance of the blur.
Basics of bokeh
Bokeh is created by your lens. It occurs when you shoot images using a fast lens with the aperture wide open, creating a shallow depth-of-field. Some of the most highly regarded lenses in photography are loved so much, partly for the creamy smooth quality of bokeh the produce. What otherwise might be a bright noisy background can be turned into a soft background that helps separate and highlight your subject.
Not all lenses produce the same quality of bokeh. The aperture blades inside a lens are what determine the quality of bokeh produced. Lenses with circular shaped blades produce a soft round shapes in the image’s bokeh. Lenses that have a more hexagonal 6-blade aperture opening will reflect that shape in the bokeh.
There is no way to measure bokeh, except by looking at an image and deciding for yourself if it looks pleasing. Good bokeh creates smooth round highlights that get more dim towards the outside. This helps the out of focus areas to blend into a creamy smooth background.
How to produce bokeh
The easiest way to create bokeh is with a fast prime lens with an aperture of at least f/2.8. You can create bokeh with a lens that has a smaller aperture, you just have to put the subject further away from the background. The more shallow the depth-of-field is and the further the subject is from the background, the more out of focus the background will be.