Photography / Tips and Solutions

Understanding Bokeh

         

Specular out-of-focus highlights have appeared in photographs since the first photos were taken through lenses. In 1997, Photo Techniques magazine introduced the word “bokeh” to the photography world’s vernacular and the out-of-focus areas of photographs have been scrutinized ever since. Before the term, there was certainly discussion about the aesthetics of the out-of-focus specular highlights of a photograph, but until 1997, there wasn’t a good word in the English language to describe the phenomenon. Credit goes to Mike Johnston, article writers Carl Weese, John Kennerdell, and Oren Grad, the Internet, and a word that no one can agree on how to pronounce, for creating a blurry background craze.

Today, there are video and photography companies, movies, software, Photoshop plug-ins, film festivals, throw pillows, a Facebook page, creative cutout plates to cover your lens, Waterhouse plates, iPhone apps, and more named “Bokeh.” A smartphone recently touted its ability to produce “bokeh” as a selling point for its built-in camera. Other smartphone cameras have algorithms in their electronic brains that can create artificial bokeh on images when their lenses fail to produce the effect. There is even a nutrition website featuring an article on using bokeh in food photography. At press time, there are more than 1.1 million images on Instagram with the bokeh hashtag. Getty Images has more than 51,000 stock bokeh photos to choose from if you need some bokeh in your life right now. Do a Google search for “What is bokeh?” and you will get more than 3.5 million results—and more than 10,000 if you use quotation marks.

Let’s clear up a few things before we dive in.

“Bokeh” is an English word that is a translation of the Japanese word “暈け” or “ボケ” that means: blur—specifically out-of-focus blur. So, why not just use the already established word “blur?” Because the simple English word “blur” can be applied to motion blur as well. Also, the word bokeh also encompasses the Japanese word “ボケ味“ meaning “blur quality.” So, bokeh is more than the blur, it is a word used to describe the aesthetic quality of blur. Because of the dual meaning, you can say, “That photo has bokeh,” and you can also say, “That image has very pleasant bokeh.” The translation of those two statements is, “That photograph has specular highlights that are not in focus,” and “The out-of-focus areas of this photograph are pleasing to the eye.”

The word is a noun. It is only capitalized when beginning a sentence. “Bokeh” is not a proper noun.

How do you pronounce it? Most people say that it is pronounced “bow” (like a bow tie) and “keh” (like the “ke” in Kelvin) with equal emphasis on each syllable. Photo Technique added the “h” to the word “boke” to help readers pronounce it correctly as they understood it. However, are several articles on the Internet from Japanese speakers that say the last syllable should be pronounced like “kay.”

So, you might want to pick a pronunciation, make your own, or just skip the word all together and say, “Out-of-focus blur.”

Please see the comments section, below, where Mike Johnston himself talks about the origin of the word. B&H would like to thank Mr. Johnston for taking the time to review the article and comment.

The other thing feeding the bokeh obsession is the fact that the human eye, due to its excellent depth of field, does a poor job creating the kind of bokeh many viewers like to see in photographs or motion pictures. Therefore, big bokeh in photographs is, in a way, a unique visual experience that can only be had by viewing an image captured through an optical lens.


Photographs © Todd Vorenkamp
 

Bokeh

If there are portions of an image that are not in focus, that is bokeh. Of course, if that which is out of focus is pure black or pure white, you might not see it. But, in general, you should not over-think this. Even though the focal plane of a lens is razor thin (see this article on focus), when photographing distant subjects, the entire image may be in focus. Out-of-focus regions occur when portions of the foreground or background are outside the lens’s depth of field (DOF).

Bokeh as a Subject

One of the anomalies of bokeh, when you consider the amount of attention bokeh receives (guilty by virtue of writing this article), is that it is rarely the subject of the photograph. Therefore, we probably should ask ourselves why it receives as much thought as it does.

 
Bokeh as the subject in this shot, taken with a Nikon AF DC-NIKKOR 105mm f/2D lens.
 

In general terms, bokeh can be one of four elements in a photograph:

1. The subject: usually an abstract image comprising out-of-focus specular highlights

2. A part of the subject: the cliché bokeh-as-part-of-the-subject image is the cup or bowl with holiday lights “pouring” into it

3. A complement to the photograph

4. Distraction from the photograph.

Complement or Distraction?

When portions of the foreground and background are outside of the DOF of the lens, the light that reflects from objects in those regions will be reproduced as circles at the image plane. The DOF article linked above contains a thorough discussion of circles of confusion. This is what is happening in the image just described; points of light are not focused to a precise point at the image plane due to the fact that the object is outside of what is in focus to the lens.

Bokeh is the visual rendering of circles of confusion.


When a point of light is at the focal plane (middle illustration), it is reproduced as a point of light at the image plane. If the point is forward or aft of the focus plane, it is reproduced as a circle—not a point.
 

Depending on how the lens elements are designed and how the aperture of the lens is shaped, the bokeh will have distinct characteristics. These characteristics will, in general, do one of three things: complement the image, be a non-factor in the image, or distract from the subject. Interpretations on the interaction of the out-of-focus areas of an image are as subjective as the photograph itself. Some find certain bokeh shapes and forms pleasing, others find some distracting. Regardless, it is subjective. When someone uses the terms, “Bad bokeh” or “Good bokeh,” know that you are hearing opinion, not fact.

As a photographer, you may want to experiment with your lenses and figure out which ones produce bokeh that is pleasing or non-distracting to your eye. You might also find that some lenses produce bokeh that makes you cringe. This is not to say that a particular lens is better or worse than another; it simply renders out-of-focus highlights in a different fashion. There are some legendary lenses that are known for their sharpness and color rendition, yet heavily criticized for their bokeh performance. Conversely, there are not-so-great lenses that create beautiful bokeh.

The bottom line here? Know your lenses and how to exploit their strengths and avoid their weaknesses. Shallow DOF portraiture usually demands pleasing bokeh. However, unless you are primarily a portrait shooter, my advice would be to not make bokeh a large part of your lens-shopping criteria unless out-of-focus abstractions are your photographic genre of choice or you are doing an art school project on the subject.

Bokeh is a Function of the Lens Design

The optical design of a lens—how the lenses are molded, polished, and placed—and the design of the aperture diaphragm are responsible for the way bokeh is rendered in an image. The next portions of this article will discuss how bokeh is created, but if you read this and crave an even more technical gaze into bokeh, feel free to absorb this linked document from our friends at the venerable lens manufacturer, Zeiss Camera Lens Division, titled Depth of Field and Bokeh, by H.H. Nasse.

For the purposes of this article, let’s try to keep the conversation relatively basic, because most of us want to spend our time making photos and not designing, molding, hand-polishing, or producing homemade photographic lenses.

Aperture and Shape

According to Schneider Optics, “Sometimes good things just happen. A good bokeh also might just happen, but it can also be designed. The shape of the iris is one of the aspects that needs to be considered.”

If you read my article on star effects, you know that diffraction caused by the shape of the aperture diaphragm will determine the shape of light passing through said diaphragm. The same diffraction applies to the shape of out-of-focus light.

On lenses with variable apertures, the diaphragm will be constructed of multiple blades that expand or constrict, depending on the selected aperture. The lens diaphragm aperture is generally designed to form a circle. The fact that several sections form the circle means that it will not be a geometrically perfect circle. Some aperture blades are rounded to maximize the simulation of a circle. However, the fewer blades the diaphragm has, the more difficult it is to form a circle, regardless of rounded edges.


You can see the Fujifilm XF 90mm f/2 R LM WR lens’s 7-bladed aperture creates a heptagon as the lens is stopped down from f/2 to f/16.
 

Therefore, for example, a lens with five aperture blades will produce, sometimes subtly, pentagon-shaped out-of-focus highlights, or bokeh. Depending on your aesthetic, this might be welcome or it may be objectionable. The more blades the diaphragm has, the more circular the bokeh will appear, especially when the light is passing through the diaphragm near the optical axis of the lens. With an eye on circular bokeh, some optics, like Rokinon’s XEEN lenses feature 11-blade apertures in an attempt to maximize roundness, even when stopped down.

Michael J. Hussmann, in Hasselblad’s Victor magazine, says, “From polygon-shaped, rather than round blur disks, one can easily determine the number of aperture blades. These shapes are rarely distracting, though, and increasing the number of blades doesn’t improve bokeh as much to be worth bothering.”

Some older lenses have aperture blades that form a kind of ninja star-shaped diaphragm that leads to a distinctive bokeh shape. For the eccentric photographer, you can create your own bokeh shape by cutting out a design of your choice in a piece of black construction paper and covering your lens with it. There are a lot of DIY videos online, suggesting different creative ideas for bokeh shapes but, if you prefer to skip the arts-and-craft project, you can just buy the DIYP Bokeh Masters Kit or the Lensbaby Creative Aperture Kit 2. Note that these custom shapes work best with bright out-of-focus regions in the photograph such as artificial lights outside of the DOF. If your out-of-focus region is devoid of small highlight regions, you’ll likely not see these shapes distinctively reproduced in the bokeh.

 
A star-shaped Waterhouse plate gives the Lomography Petzval 85mm f/2.2 lens’s bokeh a starry shape.
 

Getting back to the diaphragm aperture shape, the wider the aperture, the more round the diaphragm will be. At its maximum opening, the diaphragm is as round as it will get. The narrower the aperture, the more pronounced the diaphragm shape, if it has a shape, would be.


Simply putting your fingers in front of a lens changes the characteristics of the bokeh.
 

No Aperture: The Mirror Lens

The catadioptric or mirror lens—basically a reflector telescope—produces distinctive out-of-focus shapes popularly known as “doughnut bokeh.” Mirror lenses generally do not have adjustable diaphragm apertures. The distinctive shape of the bokeh comes from the design of the lens and the placement of the reflecting mirror in the center of the image. Light enters the optical tube, passes a small mirror, and strikes a concave mirror at the rear of the tube. The light is focused back toward the small mirror and reflected back through a hole in the concave mirror where the camera or eyepiece is mounted.

Doughnut bokeh from an LED street light, captured with a Nikon Reflex-NIKKOR 500mm f/8 (New) lens.
 

The result is bokeh with a bright edge and a relatively dark center. Some folks love this effect. Others despise it. Remember, bokeh quality is subjective.

Aperture: Depth of Field

There is nothing magical here, the shallower the lens’s depth of field (DOF) is, more regions of the image will be out of focus. Longer DOF will keep more of the image in focus and give you less out-of-focus regions.


Changing the aperture alters the depth of field and the aperture diaphragm shape to change the characteristics of the bokeh, in this series of images from the Fujifilm XF 56mm f/1.2 R lens.
 

DOF and aperture shape combine to affect the characteristics and prevalence of the bokeh. A narrower aperture gives you longer DOF and more diaphragm shape in the bokeh. A wider aperture gives shallower DOF and more rounded bokeh.

Optical Vignetting: Cat’s-Eye Effect

At wide apertures, light is entering the aperture diaphragm from a wide range of angles. Light passing along the optical axis of the lens will not have to be refracted to meet the image sensor. Light entering the edge of the lens must be bent toward the sensor. Because of the variation of the angles of light as you move from the center of the image to the edges, the shape of the bokeh changes. Instead of concentric circles formed on or near the optical axis, light coming in at an angle forms bokeh that is elliptical. These ellipses are known as “cat’s-eye bokeh,” because the shape resembles the feline pupil.


The shape of the bokeh changes ever so slightly as the tug and barge head upriver, in this series of images taken with a Nikon AF DC-NIKKOR 105mm f/2D lens.

As you extend from the middle of the frame, the introduction of the ellipse-shaped bokeh can cause a “swirling effect” in the image. Some lenses are specifically designed to produce this swirly bokeh effect, such as the Lomography Petzval 85mm f/2.2 lens (available in Nikon and Canon mounts). Lomography’s revival of the Petzval design was driven by the desire to create a lens with this bokeh effect. “For the Petzval Art Lenses, we were inspired to create them based on our love for the special swirly bokeh which Petzval lenses give. So bokeh was part of our inspiration for these lenses to create new Petzval lenses, which give the same special swirly bokeh,” says a rep from Lomography.


The Lomography Petzval 85mm f/2.2 lens is known for its intentionally swirly bokeh.
 

Another swirly lens is the Helios-44 lens family, manufactured in the former Soviet Union. The Helios lenses were based on a Zeiss Biotar design, also known for their swirly bokeh.

Spherical Aberration

Uneven shading of the bokeh shapes are determined by the amount of spherical aberration (SA) in the lens. SA is the optical effect caused when light entering lenses at different distances from the optical center are refracted more than the light passing through the optical center. Referring to SA, Fujifilm says, “One thing to note is that beautiful bokeh is the effect of beautiful contrast from smooth de-focusing area to the sharp focusing area.”

   


Spherical aberration causes light rays to spread unevenly and create variations in the shading of the disc.
 

If the lens is designed perfectly, all of the light entering the lens, no matter the distance from the optical center, converges at one place—no SA. With a lens devoid of SA, the circle of confusion discs will be uniformly shaded across the disc. If the SA is under-corrected, it causes an increase in light toward the center of the disc—a Gaussian distribution of light. The out-of-focus discs will be brighter in the center than on the edge. Finally, if the discs have more light-gathering to the edges of the disc, over-corrected spherical aberrations, you will get what is known as the “soap-bubble” bokeh effect. This bokeh resembles the aforementioned doughnut bokeh caused by mirror lenses, but it is created by aberrations, not by the blockage of light from a mirror.

Spherical aberration flavors. Over-correction causes light to build near the edges. Under-correction of SA leaves more light in the center. Some websites label these as “bad, neutral, and good,” but those terms are subjective.
 

The rub with SA is that, if you under-correct or over-correct it, you will get the opposite light distribution effect before and after the focus point. Therefore, an over-corrected lens that causes the soap-bubble bokeh in the background will have foreground-out-of-focus areas with a concentration of light in the center of the discs, and vice versa for under-corrected aberrations.

If you read other articles on bokeh, you may find that this is another area where opinion on bokeh gets thrown into the mix. The popular stance is that bokeh with bright edges is poor, bokeh with a bright center is wonderful, and neutral bokeh shading from lenses with corrected SA is, well, neutral. Again, this is just someone’s opinion.

Some photographers crave the soap-bubble bokeh effect in their images. In fact, some lenses, such as the Meyer-Optik-Gorlitz Trioplan 100mm f/2.8, are known for creating the effect. Other photographers detest the bubbles. And, as mentioned above, soap bubbles in the background means Gaussian discs in the foreground, so you need to prepare yourself for both types of out-of-focus regions if the lens is not fully corrected.

Aspherical Lens Elements

Lens designers generally try to combat SA and create “perfect” lenses. One way to remove the aberrations is through the use of aspherical lenses. A spherical lens is one that is virtually cut from a sphere; hence the name. An aspherical lens has a complex shape where the curvature changes based on the distance from the optical center. You cannot slice a sphere and create an aspherical lens. Aspherical lenses are much more complicated and expensive to manufacture than their spherical counterparts. Does your lens have aspherical glass? Many lenses containing these specially designed elements usually have nomenclature denoting the use of the aspherical elements.

Aspherical elements can also influence the rendering of out-of-focus regions by introducing what is known as “onion-ring” bokeh. This effect appears as a texture of rings on the bokeh discs and is caused by very slight defects in the lens surface. Adding to this, these imperfections can cause diffraction and result in different textures on the discs.




Onion-ring bokeh produced by the Fujifilm XF 35mm f/1.4 R lens
 

When asked about bokeh and lens manufacturing, Panasonic responded, “A unique technology that is deployed for the LUMIX G Leica DF Nocticron 42.5mm f/1.2 ASPH. Power O.I.S. lens (as well as the LUMIX G Leica DG Summilux 15mm f.17 ASPH., and the lenses in the LUMIX DMC-FZ1000 and LUMIX DMC-LX100) is a unique process for manufacturing the molds that are used to produce our aspheric optics. In the past, aspheric optics had to be hand-ground. Today they are molded, and the mold is created with a lathe that bores the shape of the lens. This process leaves concentric circles in the mold that in turn are pressed into the glass. These rings can be seen in the bokeh area of many lenses and some call it an ‘onion-ring’ bokeh. Our proprietary lens-manufacturing process requires hand-polishing of these molds to remove the rings from the mold. This gives us the look of a hand-ground aspheric lens for a fraction of the cost.”

Chromatic Aberration

Multi-colored light travels through space at different wavelengths. Different wavelengths means different speeds and, when this light passes through a lens, the different colors are refracted at slightly different angles. This causes color fringing to occur around objects in the image, especially near the edges of a frame where the light is bent more than light passing through the lens close to the optical axis. There are two basic types of chromatic aberrations (CA): lateral (left/right) and longitudinal (front/back).

Olympus examines many different bokeh factors when producing lenses, including CA. “Olympus’s optical engineers are particularly critical of bokeh design. At the beginning of the lens-design process, engineers separate bokeh into several components: shape, homogenization level of color on the inside, and color on the outline of the bokeh. Once the goal of each parameter is determined, work can begin to design the optics.”



The Nikon AF DC-NIKKOR 105mm f/2D lens shows slight chromatic aberration.
 

This CA can and will appear in out-of-focus shapes and can “color” the bokeh a bit. Lateral CA will color the edges of an object, including the edges of an out-of-focus disc. The longitudinal CA will produce a color tint on the entire disc. The more a lens is corrected for CA, the less color fringing you will see in both focused and out-of-focus regions of a photograph.

Astigmatism

According to Sigma, “Designers and engineers pay attention to bokeh in design process. [We] design the aperture blades rounded to create nicer bokeh and the sharpness of the lens to balance between the optimal sharpness and the nice bokeh. In order to depict beautiful bokeh, our engineers try to not only minimize vignetting, astigmatic and chromatic aberration, but also look into the best balance for the concentration distribution of bokeh at the development stage.”

You may have heard your optician say the word “astigmatism” during an eye exam, and if you asked them to explain it, you might be fast asleep in only a few moments. Basically, astigmatism is a defect in a lens that affects the ability of the lens to accurately focus light coming in at different angles and wavelengths. A lens can often produce a sharper image in some regions than others.

The bottom line is that this can have an effect on the shape and characteristics of not only your subjects, but your bokeh, as well.

Lenses with Adjustable Bokeh

There are a few lenses in the world with systems that allow the photographer to specifically adjust the way the lens renders out-of-focus areas. These lenses include:

Nikon AF DC-NIKKOR 105mm f/2D – DC = Defocus Control

Nikon AF DC-NIKKOR 135mm f/2D – DC = Defocus Control

Sony 135mm f/2.8 – STF = Smooth Trans Focus

Fujifilm XF 56mm f/1.2 R APD – APD = Apodization Filter

• Sigma 135mm f/2.8 YS – Focusing System

The NIKKORs achieve manipulated bokeh by adjusting the lens’s SA to control the light distribution across the foreground and background out-of-focus discs. According to Nikon, its patented Defocus Control system was combined with its innovative rear focus system to “realize the ideal lens accepted by all of those who demand sharpness or want to utilize the out-of-focus foreground, and for those who call for a soft out-of-focus background.” The design features a movable “DC group” of lenses that can shift position inside the lens without affecting astigmatism and CA.


The Nikon AF DC-NIKKOR 105mm f/2D lens shows subtle changes to the foreground and background bokeh when cycling through its defocus-control settings from front to neutral to rear.
 

The Sony and Fujifilm lenses use a “reverse apodization filter” to adjust the qualities of the out-of-focus areas. The filter is basically a built-in graduated radial neutral density filter that has darker edges than the center; artificial vignetting in a sense. This helps soften the edge of the bokeh discs—to achieve the opposite of the soap-bubble effect.

Based on research on the older Sigma lens, it appears that there was a control designed to assist in macro focusing, but a side effect of that control was SA adjustment.

Engineering Bokeh in Lens Design

Does bokeh just happen? Are you curious about whether lens manufacturers design lenses with bokeh in mind, or if there are other priorities that outweigh how a lens renders out-of-focus regions, like SA removal, sharpness, color rendition, etc? In talking to 17 different lens manufacturers, it is apparent that their approach to bokeh in the design stage varies greatly in emphasis and execution.

Tokina says, “The primary concerns are sharpness, contrast, and chromatic aberration (or lack thereof). So the short answer is that it’s not that bokeh just happens, but it is a secondary consideration that is usually handled in the mechanics/aperture of the lens.”

Of course, with lenses known for a particular bokeh effect, like the Petzval and some Lensbaby lenses, the mission is bokeh. Mamiya, who designs its leaf-shutter lenses with Schneider-Kreuznach, states that bokeh is a design consideration, but not the most important one.



 


 

Cleaning the rear element of this lens removed ugly spots in the bokeh.

As with almost everything these days, computers are heavily involved in the design of optics and also bokeh rendering. Before computers, calculations were done by hand. In 1956, Fujifilm created the first domestic computer in Japan, FUJIC, to design lenses. The computer is now in Tokyo’s National Museum of Nature and Science.

Canon’s Lens Development Group shared the following: “In order to achieve high image quality, Canon utilizes its own unique simulation software in the design phase, to confirm how bokeh changes under different shooting conditions, such as distance from the subject and aperture setting.” The company would not discuss the design specifics of its lenses regarding bokeh, but Canon did say that it is notable that the optical engineers are “using [this proprietary] computer simulation software to predict and confirm the impact of a lens design on bokeh characteristics. This is the same process used to derive our MTF performance curves on Canon lenses, and it’s interesting to learn that computer simulation is used not only to map out the anticipated contrast and resolution a given lens design may produce, but even its out-of-focus area characteristics.”

Leica’s specially designed software optimizes more than 50 parameters in the optical design with accuracy down to the length of one light wave (0.5 micrometer) to help the task of removing all aberrations. Also, many Leica lenses have aspherical elements. This precision is important when the lenses are polished to an accuracy of 1/2000mm (1,000 times thinner than a human hair).



The Brooklyn Bridge is brought into focus using the Fujifilm XF 90mm f/2 R LM WR lens.


Testing Bokeh

The rubber meets the road, so to speak, when the lens is actually built and an image is created. Computer simulation has its limits when it comes to optical design. “Because of the inherent diversity of the ‘bokeh,’ we go through design-based simulation to prototype and engineering sample-based evaluation in the lab environment, then to a field test when the final tooled samples become available. At each stage, we find something in reality. All in all, the computer-aided simulation is an inseparable process of the design; however, that will not cover the whole ground for the real-life shooting conditions,” according to Tamron. In addition, the company says, “We have to follow through up to the final field test to make sure everything is well under control.”

Olympus designs in a similar manner: “Bokeh design is ultimately accomplished by simulating how bokeh changes in both the foreground and background when varying the camera-to-subject distance while the optics are fixed at a specific focal distance. This process is repeated through the focal range of the lens until engineers are satisfied with the results. Before a lens has reached the mass-production stage, optical designers will use a pre-production example of the lens in real-world situations to validate its design. It’s at this point where engineers can make sure that the bokeh created is the same gentle and natural appearance determined by the simulation.”

Keep Bokeh in Perspective

For almost 20 years, for every conversation and website about lens sharpness, there has been a conversation and website about bokeh. Neither sharpness, nor bokeh, is usually the subject of a photograph, but they certainly are the catalyst for a lot of discussions.

Playing with bokeh, creating it, or capturing it can be fun. Definitely feel free to explore bokeh with your lenses. Just keep in mind that if you find that your favorite lens is producing bokeh that is swirly, creamy, bubbly, bokethereal [You heard that here first], bokehlishious, bokehrama, bokeawesome, bokehgross, bokehyuck, or bokehugly, try not to lose the subject for the background… unless the background is a blob of really ugly bokeh.

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It might be helpful to take the discussion to cases, for equipment, subjectand technique before either concluding it's entirely a matter of preference or that it's not a significant issue in the art or the craft of photography.

I really like the correction and sharpness offered by some (not so exotic) lenses for portraiture andproduct, such as Nikkor 85/1.4D on FF (D3) @ f/2.0-2.8, or Sekor C 150/4.0 SF on the RB67 @ f/4.5-5.6 (various films). These specifics sre mildly iconic, but not mythical. 

If you have a distaste for "hard bokeh," that you are calling soap bubble, I think, then you may see it frequently, often with television for instance. It can draw your attention. One of the worst cases is not with round specular highlights (too limited of a general casefor the whole diacussion of the subject of bokeh,) but with lines that are  doubled when seen in oof bg's, like branches of a tree: this can really be a detracting detail.

Hey TS,

Thanks for your comments!

If I understood you correctly, I will stand by my position that the quality of bokeh is still entirely subjective to the viewer as some lenses create (and are designed to create) specific types of bokeh effects that some viewers crave and others detest.

Thanks for reading!

"Bow-Kay" is indeed the correct pronunciation, since that is how the Japanese would say it, and the word a direct phonetic translation of 暈け/ボケ. 

Absolutely do NOT pronounce it as "Bo-KA," as I've often heard people do in various videos online. That is totally incorrect, not just in terms of translation, it's also incorrect based on the spelling of "bokeh." 

Hi Rob,

I think I will just refer to them as "out-of-focus specular highlights" because I am pretty sure I know how to pronounce those five words!

Thanks for writing in and thanks for reading!

"out-of-focus specular highlights" is incorrect. There is no requirement for there to be any specular highlights in the image for there to be bokeh.

Hey Peter,

It is only incorrect if you are talking about non-specular bokeh or bokey or bokay or bouquet. As I wrote in the article, the term "bokeh," regardless of its pronunciation, can be applied to describe the quality or existence of all out-of-focus regions of an image.

Thanks for commenting and reading the B&H blog!

A few days ago I posted a comment to the article about "bokeh". It never appeared though comments submitted both before and after it did. I'm curious why. Was there something objectionable, misleading, or violating some B&H policy? Please contact me at the email address given along with this question. Thank you in advance for your time.

Hey Jeff,

I apologize for your comment getting blocked. Our spam filters are very aggressive and there is a chance your email was caught in the web and accidently thrown out with the huge amount of spam we receive. Believe it or not, almost all of my replies get blocked by the spam filter...and I work here!

Could you please re-submit your comment(s)? Thank you and sorry for the inconvenience!

Thanks for reading and thanks for letting us know your comments didn't get published.

Good article and lots of good information. Thanks!

Late 1960s, Los Angeles area: The term "brukah" (approximate phonetic spelling) is used by several photographers I know when talking about out of focus areas in photos. We are all aspiring to the F/64 club where black and white photos are sharp everywhere and large-film view cameras are in vague. Out of focus areas may be appropriate for portraits and a few other types of pictures but not for "real pictures". Everyone wanted to be the next Adams or Weston.

View cameras are those cameras you see where the photographer has a black cloth covering his head and the back of the camera. They also allow relative angular changes between film and lens in order to control perspective and areas of sharpest focus. They focus an inverted image on a ground glass at the back of the camera. The black cloth helps to view the low contrast image on the glass; hand-held magnifiers help observe some details of what the picture will look like when film replaces the glass and is exposed. The lens can be stopped down to help visualization but the image becomes darker quickly. As you might guess, trying to visualize what out of focus ares will look like with this setup is nearly impossible. You usually say a little prayer that expresses hope that the details of the picture will be as good as the ground glass implies. The prayer is especially direct to areas where sharpness of focus is questionable.

So how did the word "brukah" arise in this context? A word of this approximate pronunciation is the first word in many/most prayers recited in the Hebrew language! So a photographer's "brukah" was a shorthand wish for success in those out of focus areas. Whether or not that success was realized wasn't known until after a trip to the darkroom.

Until recently, I assumed that the origin of "bokeh" was the same as described here with a slight change of pronunciation over the years. This true story might appeal to any of you who hold beliefs in a theory of "convergent" realities.

Interesting story, Jeff! Your comment actually did post (at least it is on my screen) and I replied yesterday. But, thanks for re-sharing the convergent reality! Good stuff!

Also, let me know if you still don't see your original comment and I will pass the info to our UX designers. Thanks!

I now see the original, marked posted two days ago. It wasn't there 12 hours ago. I did flush my browser's (FF 44.0) memory and did a refresh at that time to no avail.

Crazy internet! Anyway, thanks for sharing the story! Cheers!

Bokeh has nothing to do with "specular reflection" which, by definition, requires a single point of light to be reflected to a single point. "Diffuse reflection" would be a more accurate term to use in describing bokeh.

Hey Richard,

Thanks for your comments. Your mention of "specular reflection" is the first in the article and comments thus far. Your definition is correct, but I would hesitate to say that bokeh has "nothing to do" with specular reflections. Bokeh does not need to be created with reflections. Additionally, specular reflections can indeed create out-of-focus highlights in an image. In some of the example images above, you can certainly see changes in the shape and size of reflected out-of-focus highlights.

Thanks for reading!

Thanks Todd for the very informative article!

You are welcome, John! Thanks for reading the B&H blog!

Impessive knowhow brilliantly presented!

Thanks, Gert! And, thanks for reading!

Enjoyed the article!!!

Thank you, Lamar! Thanks for reading!

I love bokeh, but seriously, it does detract from the memory of where an image was shot in years to come. The background of a subject is part of it's history in a sense.

Great point, Rodrian! There are definitely times where the background gives the photograph a time and place that could have been forever lost to shallow depth of field!

Thanks for reading!

The usage of animated GIFs in this article diappointed me because the animated GIFs make it impossible to save the arrticle as a useful PDF with viewable photos, since they are animations. I would prefer that you create articles that can be saved as straightforrward PDFs, ie with no animated GIFs. Otherwise I love these kinds of tutorial articles and try to save as many as possible. This is th first time I've encountered this problem from these articles.

Hi Perry,

I was able to save the article as a .PDF at work and on my home computer. The animation does not make it to the .PDF, but stills appeared where those images lived. It may be an issue that can be resolved by your settings.

I was also able to cut-and-paste the article into a word processor and save as a .DOC file or export as a .PDF. 

Please let me know if you can get it to work for you. Thanks for commenting and thanks for reading!

It is important to recognize that depth of field is a function of magnification. Without getting into the math, this may be simplified to indicate that it is a function of sensor size. In film days, when 24x36mm was the smallest frame most people encountered, depth of field was a demon that had to be mastered in every shot. Photographers using medium or large formats had a real handful just trying to obtain adequate depth of field for their subjects.

This limitation, of course, became an opportunity for expression, and every photographer worth his/her salt used sharpness distribution in their composition, adding a sense of depth or drawing the viewer’s eye toward the intended part of the composition. Sometimes, as the article suggests, good things just happen. With the advent of digital photography, the early sensors were small, VERY small in many cases, leading to nearly infinite depth of field. Bokeh was forgotten, or never encountered by millions coming into photography after the turn of the century. I have had countless people ask me, viewing my medium and large format photographs, “How do you do that?” referring to the soft blur in the backgrounds.

The demand for “full-frame” 24x36mm sensors was, in part, driven by older professional photographers wishing to regain some control over this expressive tool, which had gone missing from their creative toolkit since they “went digital”. For others, it was a condition sine qua non for going digital.

Bokeh, and depth of field in general have been the subject of much black magic and mythology amongst amateurs. People will pretend that one lens has greater (or lesser) depth of field than another, when in fact every lens of the same focal length will have exactly the same depth of field, at the same aperture. Similarly, bokeh discussions, particularly in Japan, tend to take on an aura of product worship, (much as hi-fi audio discussions do), with the best results seeming always to be procured from the products boasting the highest price tag. Some photographers, bored with their sharp-all-over results, and wishing to emulate the pleasing sharpness distribution they observe in earlier photography, have taken to adulating lenses that have serious aberrations, or are simply unsharp all over! Photographers are paying high prices today for some early aerial photography lenses, where the designers were seeking wide coverage, but in some cases this came with so much coma the lenses were simply incapable of producing a sharp image anywhere except in the very center. True bokeh doesn’t involve bad lenses. It is a matter of placing the sharpness where you want it in the image, and carefully controlling the degree of unsharpness elsewhere.

That might well be the most intelligent comment I've read on this subject in 19 years.

High praise for Mr. Faris from the expert! Thanks for commenting, Mr. Johnston!

Hi Greg,

I'll second Mr. Johnston's comment. Great information. I love what you said about photographers around the turn of the century with early sensors.

For an exhaustive chat about depth of field check out this link.

Thank you so much for adding to the discussion and thanks for reading the B&H blog!

1997? Bokeh was discussed in photography classes I took back in the early 80s. And I had been introduced to the term in photograpy journals well before that.

Hey David,

Based on my research, 1997 was the date. However, if you have documented evidence to the contrary, please share it with us so that we can set the record straight!

Thanks for reading!

Thanks for the detailed discussion of "how and why" bokeh occurs! I have always known that the DOF adjustments with apeture settings can affect it, but this gives me more tools to creating just what I want to put into the image (and what lenses I might use) from the start!

Cheers!

Hey Thomas,

Thanks for your comments! I am glad the article was enlightening! Have fun making bokeh and thanks for reading!

I see a bunch of specs and fibers in the images.

Is this dust on the front, back, inside of the lenses or is it on the sensors?

How do you avoid this?

Thanks.

Hey Russ,

The specs are actually dust on the lens' rear element. I was surprised to see how pronounced they were on the bokeh circles as dust is really never noticeable in focused photographs. Check out the diptych in the article with the before and after cleaning images. Crazy!

I learned a lot in researching and writing this article, including the fact that the rear element must be kept clean if doing extreme bokeh! And, when I say "extreme" I mean putting your lens at its minimum focus distance and taking images of lights over half-a-mile a way.

Great question! Thanks for asking and thanks for reading!

 Hi Todd,

You mention the Sigma 135 F/2.8 YS lens in your article.  Sigma has been rumored to be working on one of these for a long time.  This is the first time I've seen anything in print referring to it. Where can we find more out about this?

Kevin

Hey Kevin,

The Sigma 135 YS lens is actually an older Sigma lens and is no longer in production. I did a bunch of searching on the internet and barely found any information about it. I guess that is a little bit of what happens when a lens lives and dies before the days of the internet! There is a little information floating about the interweb, but nothing comprehensive...yet!

Thanks for reading!

More than I ever wanted to know about Bokeh. Thank you for enlightening me and also helping to keep this all in perspecitve. Excellent work. 

Hey Rebecca,

I am very glad you enjoyed the article! Thank you so much for writing in and thanks for reading!

Todd,

Thank you for both a very informative and enjoyable piece with "lens design technical terms" which is easy to understand by the layman.  This is definitely an article to keep for future reference, so I will try the PDF save as mentioned by another reader.

Thanks again for taking the time in making a difficult subject simple enough to understand for the majority of us.

Greg

Hi Greg,

Thank you for the kind words and thanks for reading! Teaching photography is my guilty pleasure; it is my pleasure to write articles like this! I am very glad you enjoyed the article!

I want to disagree about the human eye.  The human eye iris is aprox. f1.7mm .  One can possibly observe brokeh when closing one eye focused on a close subject in low light. We do not generally observe brokeh because the human eye keeps refocusing close and far and we are seeing a compsite image based on memory.

Hi Kal,

You make a good point, but trying to analyze out-of-focus objects in my eyesight makes my eyes hurt! Time to get manual focus eyes?

Thanks for reading and writing in!

I enjoyed your article very much. I'm writing to note some pre 1997 hisory of the word "bokeh".

A similar sounding term was used in the Los Angeles area cira 1970. You may or may not know that the first word in the Hebrew version of many Jewish prayers was "brukah" (that's supposed to be a phonetic approximation). So saying something was a "brukah" was a way of saying it was a prayer or an answer to one. In the era I'm talking about we were all influenced by the F 64 Club and view cameras. Everything in most photographs was to be in sharp focus; protraits and few other things were exceptions. We talked about "brukah" when a scene was so ornary that some parts were out of focus: we meant "I'm saying a prayer that the out of focus areas will look good." There was no real way to tell looking at the focusing glass in a view camera and it was a sort of joke.

I thought that was the origin of the term and never doubted it until I read the above. I also thought the term was slightly mispronounced!

Hi Jeff,

Fascinating and entertaining, especially because of where I work! Maybe it all started back then!

Thanks for sharing and thanks for reading!

Excellent writing style, excelent information with good backround details to crystlalize a "blurry" issue,,Thanks,, 

Thank you, Huseyin! 

I am glad you enjoyed the article! Thanks for reading!

Great article Todd!

Thank you, Don! Thanks for reading!

Any relation to the former Gunbearer named Don Strasser?

I am SO sick and tired about hearing people enthuse and drone on about bokeh.  I've been a photographer for 54 years....taken a LOT of photos with film cameras and digital camera.   I could care less about bokeh.   Articles like this one just perpetuate the insanity of focusing on something that is totally secondary to the photograph.  Focus on the SUBJECT people......that's what matters.   Mr. Vorenkamp....shame on your for perpetuating this nonsense.  It may be second only the the equipment lovers who enthuse and brag about the expensive camera that they bought, but have yet to take a single decent photo with same. 

Mr. Kuehn,

Call me Todd! "Mr." makes me sound old.

Thank you for your comments. I agree about the absurd amount of traffic that the subject receives and I attempted to point that out in my introductory paragraphs as well as admitting my culpability in writing on the topic.

I also ended my piece with a paragraph entitled "Keeping Bokeh in Perspective" where I discuss exactly what you have said in your comment.

Having said that, there is a lot of bad information on the subject circulating the internet and, in talking to photographers, a desire to learn about the subject. That is why B&H now has an article on the topic.

Thank you for reading!

Brian, look at this: http://www.alaska.net/~rowlett/images/noctilux/mimi4.htm

Can you not see that the out of focus elements are an important element of that photograph? Is it exactly the same photograph with just the in-focus elements included? Blur might be "totally secondary" to a great many photographs, but it is an indivisible contributing element to a great many more. Unless of course your interest in photographs is exclusively and entirely evidential and not at all aesthetic.

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