Bokeh, a Japanese word meaning "out of focus" that can become very pleasing to the eye in a photograph. Bokeh is pronounced BOH-Kə or BOH-kay.
According to Wikipedia, bokeh “is the aesthetic quality of the blur produced in the out of focus parts of an image produced by a lens… and has been defined as the way the lens renders out of focus points of light.” So bokeh refers to the quality of the blur achieved by a narrow depth of field.
Differences in lens aberrations and aperture shape cause some lens designs to blur the image in a way that is pleasing to the eye, while others produce blurring that is unpleasant or distracting. Bokeh that is preferable will have nice round fuzzy spots of the appropriate colour for each highlight. Bad Bokeh will have funny shapes and bad colour fringing. or just not be blurry enough.
How to Achieve Nice Bokeh ?
Use the Right Lens.
Set to Largest Aperture (smallest F number) available on your lenses.
Have the Subject as close to the lens as possible
Increase the distance between the Background and your Main Subject.
The Following information about Aperture & Lens Quality can be found at Expert Photography
Firstly, the aperture decides the shape and some of the size of your bokeh. Smoother bokeh’s are much nicer to look at and there are two ways to achieve the smoothest possible bokeh. Firstly, if you open up your aperture to the widest it will go, ie. 1.8, then the aperture blades will not be obstructing any light, and the aperture will be smooth all the way around. The second option is to use good quality lens. I would recommend opting for a better quality lens rather than widening the aperture all the way, and you’ll see why further down the page.
The quality of your lens will always effect the quality of your aperture, purely because of the number of blades that are used to produce an aperture. Higher quality lens have more blades, so they can better reproduce a circle shape. For example, my Canon L lenses each have 8 blades, whereas my kit lens and 50mm f/1.8 only have 5. Here’s what these blades look like inside a lens. It’s worth noting that the narrow the aperture becomes, the less obvious this comparison becomes.
And here’s a comparison between the two lenses.
Position your subject…far from the light source.
Novice photographers often put their subject directly in front of the background, or even leaning up against it. But, the farther your subject is from the background, the blurrier the background will be. To create bokeh, the background needs to be blurry, so make sure to position your subject at least a few feet in front ahead of the light source. If you don’t have a camera with manual modes (which we’re talking about next), you’ll want to get even further away.
Outside of using distance to blur the background, distance will affect how big those light orbs appear. So, if you want larger orbs of light, you’ll need to place the subject a little bit closer to the light source. For smaller circles, put even more distance between the subject and the background.
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