Bokeh comes from the Japanese word boke (ボケ), which means "blur" or "haze", or boke-aji, the "blur quality." Bokeh is pronounced BOH-Kə or BOH-kay.
Bokeh is defined as “the effect of a soft out-of-focus background that you get when shooting a subject, using a fast lens, at the widest aperture, such as f/2.8 or wider.” It produces soft orbs of out-of-focus highlights.
The lens used determines the shape and size of the visible bokeh. Usually seen more in highlights, bokeh is affected by the shape of the diaphragm blades (the aperture) of the lens. A lens with more circular shaped blades will have rounder, softer orbs of out-of-focus highlights, whereas a lens with an aperture that is more hexagonal in shape will reflect that shape in the highlights.
Here is my bite sized guide to achieving bokeh in your photographry
Achieving bokeh is much simpler than you think so don’t worry too much about the technical aspects of this effect. As long as you have a camera that allows you to control your DOF, then you can easily create shots with mesmerizing backgrounds:
1. Chose the right lens.
You will need a lens with an aperture of at least F/2.8. Here i used a 50mm f/1,8 lens with the aperture right open.
2. Shoot in AV or manual.
If you don't have time to fiddle around getting your exposure correct then AV will allow you to set the aperture and work out the rest for you. I was in manual here because that's what i'm used to and i wasn't in any particular hurry.
Lights from buildings & street lights work well for your background as does light reflecting on water. Christmas is also a great time to play around with bokeh because you can capture some lovely images of fairy lights with great bokeh. All of these will create some captivating bokeh effects.
Look for locations with colorful light sources to allow you to experiment with different hues and patterns for your bokeh. Manually focus your lens to blur a scene if you're curious to see how it would look like as a bokeh background. Take some test shots and figure out how to compose your image.
In these images it had just recently rained and then the sun came out again and it was that lovely golden hour time of day.
4. Focus on the subject
Sometimes, choosing the largest possible aperture also could make your focus “soft” due to the shallow depth of field. To avoid this, select an aperture that doesn't only make the background blurry, but also ensures that the object you want in focus is tack sharp. It’s not always necessary to use your lens’ maximum aperture. For instance, if your lens opens all the way up to f/1.4, you can choose f/1.8 or f/2.8, instead to ensure the subject is in focus.
5. Consider the distance between your subject and the background
Typically, the farther the object you’re photographing is from the backdrop, the better the bokeh. Just a few feet of gap won’t do the trick. A couple of meters or more is best.
The ideal distance depends on the situation. The greater the space between the subject and the background, the smaller the lights and the patterns will appear.
If you want big light orbs, then you have to keep your model close enough to the light source. Alternatively, you can use a lens with a longer focal length (such as 135mm) to create large orbs without having to move closer to the backdrop.