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Bokeh. What the hell is it?

Bokeh. Have you heard this term bandied about in conversations while looking at a photo, listened while someone proclaimed that the bokeh in a photo was good or bad, but you’ve been too embarrassed to ask just what it is? It’s something every photographer should understand because it affects your image. And whether you know it or not, you’ve probably evaluated the bokeh in your own photos. Well hide your shame no longer. After reading this article, you will be able to hold your head high and raise your nose as you talk about the bokeh in your next photo.

So, what is bokeh, exactly? Simply, when someone talks about “bokeh” they are referring to the out of focus portion of a photograph, usually the background, especially highlights in the background that can appear as blurry circles. Bokeh comes from the Japanese word boke which means blur (Wikipedia: Bokeh). When photographers discuss bokeh they are talking about its aesthetic quality. And as silly as it might seem, bokeh can be an important consideration in many photographs.

Smooth bokeh
Smooth, delicious bokeh. 1/60s @ f/2.8

But isn’t blur, well, blur? Well, no. Different scenes shot with different cameras and different lenses at different apertures all produce different bokeh. Any one of those factors can change its character. Now, obviously, bokeh is subjective. Many people don’t care about it at all. But many others consider bokeh an important part of a photograph, particularly in portrait photography. In fact, some people consider it so important that they’ll buy thousand dollar lenses that give you a little extra control (Nikon, for example, has a couple of lenses with “defocus control” that affects the bokeh).

Bokeh example
Bokeh example. 1/400s @ f/5.6

The shape of out-of-focus highlights is influenced by the shape of the aperture opening in the lens. The aperture is made of a diaphragm with several blades that allow it to open and close. The more blades, the rounder the opening. Some lenses even have curved rather than straight edges on the diaphragm blades to make the opening more like a perfect circle.

Christmas lights
I rather like how the christmas lights stand out in this. 1/125s @ f/2

Only you can decide if you like a particular photo’s bokeh or not. It’s a matter of taste. But in general, smooth bokeh with blurry, round highlights, soft edges and uniform brightness is preferred over harsh bokeh with polygonal highlights and hard edges. One thing you definitely don’t want bokeh to do is steal attention away from your subject by being distracting (unless, of course, your subject is the bokeh itself). If you’ve got distracting bokeh in your image, here are a couple of things you can do:

  • Open the aperture. The wider the aperture opening, the fuzzier the background will become.
  • Close the aperture. The smaller the opening, the sharper everything will be. If nothing is out of focus, there is no bokeh.
  • Change the distance between you and your subject. Bokeh looks different at different distances.
  • Compose your scene so that there are no bright highlights in the background. Bright highlights are often the culprit when a photo is said to have “bad” or distracting bokeh.
  • Change lenses. Different lenses will produce different bokeh. It’s for this reason that some lenses are said to have “good” bokeh.

Do you have any bokeh tips or opinions? Please share them in the comment space below.

Update: Photodoto reader, Dave, sends in an example of what he considers really bad bokeh. Below is portion of the background from that photo:

Bad bokeh
Bad bokeh

Notice the odd, distracting texture from hard edges in the highlights. Thanks, Dave!

John Watson

John is the original founder of Photodoto, but after running it for 4 years he had to focus on different things. If you're interested in what John has been up to recently, you can check is personal blog or browse his photo blog.
  • I find most people don’t even know they’re noticing it, but good bokeh can make a good picture a little better, and awful bokeh can ruin it (particularly on mirror lenses).

  • Wow, thanks for the explanation! I had no idea what bokeh was, and kept meaning to look it up but never got around to.

    Your explanation was very easy to read and understand. This blog is so helpful. Congrats!

  • six

    john — may your wellspring of creativity and generosity never run dry! i’m such a fan…

    this entry is great. the whole concept is wonderful. you enhance the community so much. thanks.

  • Since bokeh is something you notice mostly when it’s bad, it would be good to put an example of bad bokeh as well. I have some examples I can upload from my Canon f/1.8 mkII lens; it’s a nice sharp lens, but the 5-blade iris, oddly-shaped field of focus, and diverging radial and axial MTF characteristics make for bad bokeh in certain situations, particularly with really bright out of focus highlights. The result is a sort of “vibrating” effect that distracts from the subject.

  • SeanS

    dave – pls post, it’d be informative… I suspect most of my bokeh’s have been of the bad sort…

  • shenmue

    so, which one actually the bokeh is? is it that blur background or is it that blurry circle highlight in the blur background?
    or, yes u can say that bokeh is no different with a blur background?. is it just another name of a blur BG?

  • Bokeh refers the quality of the entire out of focus area. Every bit of light coming from the background creates a blurry circle. The highlights just stand out because they are brighter.

  • Pingback: 2. Good bokeh or bad bokeh « Bath Portraiture Class()

  • Bokeh is most affected by spherical aberration of a lens, an intrinsic property. THis is one reason expensive lenses are expensive. Spherical aberration is when the light rays hitting the outside of the lens focus closer than the focal point, leading to either a nice smooth blur for background objects, or a ring for foreground objects. Most lenses are slightly overcorrected for spherical aberration, leading to rings of light in the background, and this leads to most of the problems we see in images with “bad bokeh.” For useful details and diagrams, see: http://bokehtests.com/Site/About_Bokeh.html

    Klaus

  • So I totally get the idea of bokeh… but I still have a hard time identifying good vs. bad sometimes. Please take a look at this image and tell me what you think. Good bokeh or bad bokeh? I see a nice soft bg, but I do see some distracting lines too. My walk-around lens is a Sigma 18-200 f3.5-5.6 OS (http://www.sigmaphoto.com/lenses/lenses_all_details.asp?id=3324&navigator=6), which is what I used in this shot (http://www.jpgmag.com/photos/1570246). Thanks!

    • It’s “good” if you like it. Beautiful bokeh is in the eye of the beholder.

      • Thank you. — Yes… yes, but you know what I mean. Some people are happy if they break 80 in their golf game, but they wont be on the PGA Tour any time soon. So that said, where do you think the shot would rank on a 10 scale? 10 being perfect, 1 being ‘I wouldn’t want my name anywhere near it’.

  • Izabella

    I found this site did a great job of explaining bokeh and how imperfect lenses can often produce better bokeh:

    http://www.kenrockwell.com/tech/bokeh.htm

  • Bokeh is just the description of the airy disk at some other focus point other than at where the CoC is smallest – it’s a stupid, exotic sounding word which some magazine writer misappropriated and managed to fool people into thinking it’s something novel when in reality the idea has existed in different terms since the late 1800’s.

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