[Ed. Note: This started out, this morning, as the republication of the article "What Is Bokeh?" from 2009. However, I ended up revising it extensively. This version is based on several of my earlier articles about the subject.]
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There are three common types of blur in photographs. Two are caused by movement. Moving the camera while the exposure is made, either deliberately or accidentally, is called "camera shake."
Example 1 by Tone
Example 2 Ray Graham
Blur because the subject moved while the exposure was being made is called "subject motion."
Example 1 by Aaron Reed
Example 2 by PhotoJunket
Example 3 by Roberto Rodriguez Adam
When the above two kinds of blur are deliberately combined, usually by trying to follow a moving subject with the camera during the exposure, it's called "panning."
Example of panning by Wanda Scott
The third common kind of blur is when parts or all of a picture are "out of focus" (o-o-f) or not within the depth of field (d-o-f). This is usually called "focus blur."
Example 1 by Zoran Rodic
Example 2 by Patrick Marioné
Example 3 by Reinhard Gruber
(Example 3 under "subject motion" is also an example out-of-d.o.f. blur or bokeh.)
Putting the plane of best focus in the wrong place is called "misfocus." (A fourth kind is software-generated blur such as the "Portrait" setting on my iPhone, but that's beyond the scope of this post.)
Example of misfocus by Meestro
As an aside, note that all three of these types of blur are common causes of less than perfect clarity when they are present in small amounts below the threshhold of conscious recognition. We became much more aware of this when digital came along and we could pixel-peep our files at any magnification. Even now, though, very small amounts of motion blur, camera shake, and misfocus are very common in pictures people assume are "fine." And, indeed, in some cases they don't ruin the picture. People actually have a pretty good ability to look at the image subject when the image isn't perfect.
"Bokeh" simply refers to out-of-focus blur or the parts of a photograph that are out of the depth-of-field, and, especially, the subjective aesthetic quality of out-of-focus blur. It derives from the Japanese word that more or less means "fuzzy," which also sometimes has the sense of "fuzzy in the head," i.e., confused. That works nicely.
Highlights
Bokeh includes, but is not limited to, consideration of out-of-focus specular highlights. Out-of-focus specular highlights (here's an example) are simply where aperture shape will show up most easily in pictures (i.e., spots of bright sky in out-of-focus foliage, for example). The reason the Internet thinks "bokeh" only refers to highlights, and that the shape of the aperture blades are the defining feature, is because that's the most obvious effect.
Section of search results page for "bokeh" on Flickr. The Internet thinks bokeh only means out-of-focus light sources and specular highlights, which is wrong.
The only lens I ever got rid of because of its specular highlight bokeh was a Zeiss 100mm ƒ/3.5 for the Hasselblad. (An extremely sharp lens.) It had five aperture blades, and small, bright out-of-focus spots were perfect pentagons. Specular highlights tend to pick up the shape of the aperture (here's an example—the shape of the out-of-focus highlights are the shape made by the aperture blades). Lenses with rounder aperture shapes avoid rendering specular out-of-dof highlights that way, but rounded aperture blades merely help a little in certain situations—they don't create good bokeh all by themselves. It's much more complicated than that.
A tip, though: if your lens's aperture has a distinct geometric shape that you see in specular o-o-f highlights, remember that it's probably still perfectly circular wide open, so you can sometimes avoid the aperture-shaped "blobs" that way.
The three original articles about bokeh were published in the March/April 1997 issue of Photo Techniques magazine, which I edited at the time. Carl Weese was the one who introduced me to the idea. Oren Grad, who speaks Japanese, clarified the terminology. The articles were written by John Kennerdell, Oren, and Harold Merklinger. Harold's article is online at The Luminous Landscape. Oren and John still write on occasion for The Online Photographer.
The only reason I added the "h" to the end of the Japanese word in the magazine was that English speakers persistently mispronounced "boke," which at one time (but no longer!) was the more common romanization of the Japanese katakana characters. It's properly pronounced in two syllables, "bo" as in "bone" and "ke" as in "Kenneth" with equal stress on each syllable. "Bokeh" simply renders that a little more accurately. At least adding the "h" stopped all the "toke" and "bloke" jokes.
The word or spelling have nothing to do with the word "bouquet," from the French, and is not even pronounced the same (bo-keh versus boo-KAY).
The other nice unintended consequence of the alternative spelling was that it made the term easily searchable on the Internet. In the weeks following the publication of the issue, I was able to watch as the number of LexisNexis search engine hits (1997 was pre-Google) for "bokeh" went from none, to 15, to 90, to 450, to 8,000 and so on. (A Google search just now yielded 70 million results.) It was as if I had tagged a word the better to track it, like a naturalist might put a transmitter collar on a wolf. We literally watched it spread.
Some photographers apparently object to the word. It's been called "pretentious." It's not, any more than the terms "sharpness" or "saturated" are pretentious. It's simply a descriptive word for a property some photographs exhibit and some do not. It's shorter than saying "the way the lens renders out-of-focus blur (or out-of-d.o.f. blur)," which is the equivalent in English. That's all.
In this picture, everything but the screen is out-of-focus blur.
There's also no "good" or "bad" bokeh, at least not per se. As my father likes to say, "If it works, you're right, if it doesn't work, you're wrong." Same for bokeh: if you like it, then it's good. If you don't like it, then it's not so good. That goes for the presence of blur, as well as for its specific properties. Some people just don't like blur in pictures at all. And some pictures have none.
There's some agreement as to what's good and what's bad, but it's very rough. For instance, people seem to dislike "ni-sen" (Japanese for "double-line") bokeh—here's an example—but the late Phil Davis (author of Beyond the Zone System, a book every large-format black-and-white photographer should own) showed me a picture he liked taken with a very odd, very old camera that featured a church steeple way in the distance. The lens had rendered it as two very blurry church steeples, quite widely separated. I've still never seen more egregious ni-sen. Phil liked the effect enough that he framed the picture and hung it on his wall. (See above, under "if you like it....")
It's true that I got very obsessive about it for a long time (which I don't recommend), but my own opinion is simply that the blur should be unobtrusive, and not detract from or call attention away from the in-focus areas of a picture, unless you mean it to.
"Selective focus," another term causing confusion, just means the tactic on the part of the photographer of choosing which part of a picture is in focus and which part isn't—hopefully, photographers know enough to control which is which. (Some photographers don't, sadly. I see a lot of close-up portraits of dogs where the eyes are in focus and the end of the nose isn't, which bugs me like a bad tpyo.) The opposite of selective focus is sometimes called "pan-focus," which just means that everything is sharp from front to back. The term pan-focus has nothing to do with panning, which is a different technique altogether. I know, photographic terminology is a mess and getting worse. Don't blame me.
The King is dead
Then there's the issue of the applied connoisseurship of lens bokeh—specific aesthetic effects, or the adjective preceding the word. The Japanese term for the character of the bokeh (according to Oren) is boke-aji, which translates roughly to "flavor of blur." Typical "flavors" might be harsh, jarring, smooth, fuzzy, gentle, tizzy, confused, soft, etc. Just ordinary descriptive words.
In the early 2000s I created a .PDF download ranking some specific lenses for boke-aji. It's of limited usefulness these days, because all of the rankings are for old film-camera lenses, but here it is if you're curious. Remember, though, the ratings are just my own opinion. There are no agreed-upon standards.
There's also no perfect lens for bokeh. Please don't ask me how I know; I mentioned obsession, and it's very painful to suffer from such a blatant mental infirmity. Well, okay, the correct word is embarrassing, not painful. An acquaintance from Minneapolis once sent me a picture postcard that had an out-of-focus brick wall in the background. I looked at the picture first, and my eyes went right to the brick wall, because such regular but contrasty subjects are good at revealing shortcomings in the blur behavior of a lens. Then I flipped over the card to find that Gary had written, "As Mike's eyes go straight to the brick wall...."
He got me.
And as for "the King of Bokeh," which is what I unfortunately dubbed the Leica Summicron 35mm ƒ/2 version "IV" in a caption in the original articles: well, it's not. It's just not. I had no idea that reputation could adhere so firmly and so persistently to that lens even now, more than 20 years later, due to such an offhand comment! Here's what I should have said, if I could have explained myself better: that lens has nice, tight, coherent background bokeh when you shoot it stopped down and focused on middle distances, say, five feet and farther. "Nice, tight, [and] coherent" is merely the kind of bokeh I happen to like in B&W; and I always stopped that lens down at least one stop and usually two or three—honestly, I don't think I ever shot with it wide open in all the years I owned it; and "focused on middle distances" is how I usually shoot. So I'm sorry; I shouldn't have generalized. Troublemaker, I am.
'All generalizations are wrong'
As a general rule, I've found that bokeh gets progressively more problematic:
- the larger the aperture (meaning, the more aberrations come into play)
- the closer the focus
- the more distant the background from the plane of focus
- the more complex and/or contrasty the background
What these rules of thumb predict, quite naturally, is that you’ll have an easier time avoiding distracting bokeh with most lenses if you stop down a bit, keep the focus at moderate distances, and avoid contrasty backgrounds. With any lens, we discover our own limits for what we’ll tolerate, and then either shoot within those limits or deal with the consequences. The above rules of thumb also predict that “worst case” bokeh is easy to provoke: it’s when you use the lens’s widest aperture, focus as close as the lens can, and include deep background with complex subject matter or harsh contrast.
Front and rear bokeh (meaning in front of, or behind, the plane of best focus) might also differ.
The important thing to realize here is that there's no such thing as "the" bokeh of a lens! As the above indicates, the same lens can render blur differently depending on how a picture was taken and on what it shows; the bokeh can even be quite different in different areas of the same picture.
One thing I've noticed over the years is that if the bokeh is generally better, the in-focus image is generally a little softer and gentler, and not so "hard sharp" or "wire-sharp" as virtually all modern lenses have become. This is just a very rough equivalence and not a hard-and-fast rule. I might have said in 1997 that this was true of Bronica and Minolta film-cameras lenses generally, except I would never have dared to suggest that any brand of lens was less than super-sharp; that would have been the mafioso's kiss. Also, bokeh looks better in B&W.
No one lensmaker makes all its lenses with the same bokeh characteristics, so none can be said to be "best," and, really, no one lens can be better than any other at rendering bokeh because it's a matter of taste! I've seen statements like "this lens has beautiful bokeh" made about bokeh I personally think is atrocious. That doesn't mean they're wrong and I'm right, though. It just means my taste differs from theirs.
In general, digital lenses do better with bokeh than film lenses did. Probably because, post-1997, it started being talked about more and more (you know, from zero hits to 70 million hits), and lens manufacturers haven't got their heads in the sand. I've even seen the word used in lens advertisements. Lots of post-1997 lenses have really nice bokeh. I love the PanaLeica 45mm Macro, for example. (No, not a King. It's not even the Marquis of Bokeh. It just has pretty bokeh that I love. You can see an example in this post.)
One last curmudgeonly grouse on this subject: sometimes I think I helped create a monster. Please, Internet: bokeh isn't necessarily a desirable property all the time, and more of it isn't automatically better! Many beginners and a few ignoramuses on the Internet seem to assert that the greater an area of a picture is out of the depth of field, the better a picture it is. That's nonsense. I've even heard people say that since they paid extra for a fast lens, they're going to shoot it wide open all the time! How wrongheaded can you get? It's like saying a B&W print is better the more black it has in it. (They paid for that silver!) Photographers always try to get the placement of focus right and the depth-of-field right, and that doesn't mean more or less of one or the other—it means the picture should have what it needs according to your best judgement. Photography isn't about all-purpose rules applied rigidly to all circumstances. Get the dog's nose in the depth-of-field, please!*
Learning how your lens renders blur is no different from learning its other characteristics, such as whether it's unsharp at certain apertures or whether it smears the corners or whatever. Some people like that kind of thing, some people don't. It's all good. Want my advice? Don't obsess about it. (I know whereof I speak.) If you want to learn about it so you can attempt to apply it or control it, fine; if you don't, and prefer just to take pictures and let the chips (both the sharp and the blurry chips!) fall where they may, that's fine too. We're all just having fun here, after all.
I'm off till Sunday. Have a nice weekend! Get out and take some nice blurry pictures why don't you.... :-)
Mike
*I love that picture. Love that expression. The joke is, when you want to get the dog's nose in the d-o-f, one way is to photograph a dog with a shorter nose!
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(To see all the comments, click on the "Comments" link below.)
Featured Comments from:
JH: "Re 'All generalizations are wrong': I use this all the time in the form of 'All generalizations, with the possible exception of this one, are false.' It's a paraphrase of the philosophy of Kurt Gödel who proved mathematically that some things could not be proven, so he switched to philosophy."
Kurt Gödel and Albert Einstein, c. 1933
JG: "I frequently photograph my dog, a white standard poodle, using my Sony RX1, which has a 35mm ƒ/2 lens that renders photos in such a gorgeous way that I happily live with its many quirks and marginal reliability. Her nose is so long (approx. 6"!) that even with the lens stopped down to ƒ/8, it's impossible to get both it and her eyes in focus if I photograph her face straight on. At typical portrait distances, it's even difficult to get her nose and eyes in focus with her head turned 45 degrees, so photographing her well is more of a technical challenge than many people might realize."
marcin wuu: "There's a great read about bokeh and depth of field on Zeiss's website. Easy to understand yet scientifically sound, the best kind of article you can imagine. Funny thing about what's good and what isn't in the context of animal photography—as a cat person and shallow d-o-f fanatic, I suffer greatly because it's so much harder to put cat's nose out of focus with modern tiny sensor cameras—a cat's muzzle is way shorter than a dog's."
Mike replies: An excellent paper...I assume, as much of it is well beyond my own expertise! I particularly liked the sentence, on page 26, "The most important and clearest attribute of blurring is simply the amount of it." True dat.
The paper is a bit ironic for me however. In 1997 I had access to Zeiss's spokesperson. I can't come up with his name just now (my aging brain!) but he was quite an enthusiast (a resolution fanatic) and very intelligent, and perhaps a bit imperious as well. When I asked about Zeiss's position on the issue of "bokeh" (explaining what it meant), he reported back that he had inquired of Zeiss's lens designers but was met with perplexity. Apparently no one then at Zeiss had the habit of considering how the out-of-focus areas were visually rendered in pictures. I was told some version of the same thing we heard all over: you are supposed to look at the stuff that's in focus, not the stuff that's out of focus. Which is fair enough.
By the way, since then, I think Zeiss is one of the companies that has used the word "bokeh" in its advertising, if I'm not mistaken.
Relevant to what I said about small amounts of blurring degrading quality, I had been puzzled by an illustration photo in a then-recent Contax brochure that purported to show the resolution of one of Zeiss's best lenses for that system, but that, to my eye, was clearly slightly degraded by motion blur (and I was seeing just the printed brochure, not the original slide or print). The spokesman knew nothing about it and said that Zeiss had nothing at all to do with Contax's brochure pictures, which was doubtless true. I was curious, however, and at the time I had a practice of occasionally trying hard to get to the bottom of a random selected mystery—a good habit for a journalist, I've always thought—and I chased down the story about that particular factoid. At Photo East the next year I found the guy who knew the story. It turned out that the picture had been taken by one of the PR people tasked with writing the brochure, someone who wasn't even really a photographer. It was these sorts of facts that I learned to keep to myself, though, because in our industry it wasn't very difficult to get blackballed if you embarrassed somebody. I was already on the "outs" with Contax at the time, so I kept my mouth shut about that little point. I hope now that Contax is long out of the camera business, and the camera that brochure was concerned with is selling for peanuts on eBay, I won't get in trouble for saying this! (The Zeiss lens that made the picture is excellent; I actually still have one.)
Speaking of keeping one's mouth shut, my friend Jerry K. (who provided the picture of the soccer ball in the fishing net the other day) told me a joke yesterday. Seems an older gentleman had just passed his 60th anniversary, and was asked what the secret to a long marriage was. He said, "I've learned two things. To do what I'm told and to keep my mouth shut."
The interviewer said, "Oh, really? What if you wanted to tell her something nice, for example, that her figure looks particularly nice in a particular dress?"
The old man considers this thoughtfully for a few beats, and then says, "I wouldn't risk it."
John Krill: "Speaking of the dog's nose this photo was taken in Vietnam. The dog got so close that its nose was out of focus. Sadly the dog was killed by a land mine but his handler survived.
"Follow this link to see the photo and the story."
