Bokeh — or that "out-of-focus blur" — makes photographs visually appealing, forcing us to focus our attention on a particular area of the image. To achieve bokeh, try these photography tips:
Fast aperture is best (at least f/2.8). To achieve bokeh in an image, you need to use a fast lens—the faster the better. You’ll want to use a lens with at least an f/2.8 aperture, with faster apertures of f/2, f/1.8, or f/1.4 being ideal. However, don't worry if you don't own a very fast lens. By increasing the distance between the background and your subject, you can see bokeh in images that are shot at smaller apertures like f/8.
Use fast prime (fixed focal-length) lenses.
Long focal length creates more extreme bokeh.
Shoot lenses wide open. You’ll want to shoot with the lens wide open, so you’ll want to use a shooting mode of Aperture Priority or Manual. Manual gives you the ability to choose both your aperture and shutter speed, whereas Aperture Priority allows you to choose the f/stop while the camera chooses the appropriate shutter speed for the exposure. You could also use the Flexible Program mode, choosing the widest possible aperture/shutter speed combination.
Increase distance between subject and background. To increase the likelihood of creating visible bokeh in your photographs, increase the distance between your subject and the background. You can do this by decreasing the distance between the camera and subject. The more shallow the depth-of-field, or further the background is, the more out-of-focus it will be.
Move closer to your subject.
Take close-up portraits and macro images in nature.
Use a backlight, side light, or hair light. Highlights hitting the background will show more visible bokeh too, so if you’re using a backlight, side light, or a hair light, the bokeh may be more pleasing to the eye.