Photography Bokeh Effect, Techniques for Obtaining and Using In Your Images
Authored by: Jeffrey W Burger ©
What is Bokeh?
Wikipedia defines it as:
In photography, bokeh (Originally /ˈboʊkɛ/, /ˈboʊkeɪ/ boh-kay — also, sometimes pronounced as /ˈboʊkə/ boh-kə, Japanese: [boke]) is the aesthetic quality of the blur produced in the out-of-focus parts of an image produced by a lens. Bokeh has been defined as “the way the lens renders out-of-focus points of light”.
Okay, so now we know that bokeh refers to the rendering of out-of-focus points of light in a photographic image (technically). However, for this discussion, we will be referring to bokeh as out–of-focus parts of a photographic image. So, the question becomes
(1) How do we create this effect;
(2) Why would we want to?
Let’s start with… How do we create this effect?
While all DSLR (Digital Single Lens Reflex) lenses can achieve some amount of bokeh (we will discuss the technique shortly) not all lenses are created equal. If you are interested in creating an extreme bokeh effect in which it is difficult to even recognize the background (or any out-of-focus part of the image)… then we initially start to achieve this desired result with a lens capable of large apertures.
What? You may have heard of the term “fast lens or fast glass”… well, this simply refers to the aperture openings the lens is capable of achieving… commonly referred to as an f/stop. When you are able to open up the aperture settings to f/2.8, f/2.0, f/1.8, and, etc… not only are you able to obtain shallow depths of field (needed to create the bokeh effect) but you are also letting in more light to the camera sensor… which in turn results in faster (shorter duration) shutter speeds (so as not to overexpose the image)… hence, the terms “fast lens or fast glass”. Sorry, for the slight digression… back to depth of field and the bokeh discussion.
Wikipedia defines an f/stop as:
In optics, the f-number (sometimes called focal ratio, f-ratio, f-stop, or relative aperture) of an optical system is the ratio of the lens’s focal length to the diameter of the entrance pupil. It is a dimensionless number that is a quantitative measure of lens speed, and an important concept in photography. The number is commonly notated using a hooked f, i.e. f/N, where N is the f-number.
As a visual reference of an f/stop and corresponding aperture opening;
The first requirement of achieving a pleasant bokeh effect is a lens capable of large aperture openings. Typically, an f/4.0, f/3.5, f/2.8 or larger aperture is used to obtain pleasant bokeh. However, if you are after the extreme drool worthy bokeh then a larger aperture of f/2.0, f/1.8, f/1.4 or f/1.2 will be necessary. I should mention (and as seen in the illustration above) a smaller f-stop number indicates a larger aperture opening, and, therefore, a shallower depth of field… which equals bokeh.
So, what else is required to obtain the elusive bokeh? If we return to the Wikipedia definition of an f/stop, we will see the following text highlighted… the ratio of the lens’s focal length to the diameter of the entrance pupil… hmmmm! Simply put…adjust your f/stop to a lower number (therefore increasing the aperture opening size) and (if using a zoom lens) increase the focal length.
So, now we have two components of obtaining pleasing bokeh:
The aperture setting, and, the focal length; and,
The final components… move closer to the subject intended to be in focus and separate your subject from the background.
Let’s recap our discussion of obtaining pleasing bokeh in our photographs:
Select the correct lens (remember not all lens’s are created equal!). If you desire a fair or extreme amounts of bokeh in your photographs, then you will need to select a lens that has the capability of larger aperture settings f/4.0, f/2.8 or larger). However, as stated earlier… all DSLR lenses are capable of producing bokeh… it’s up to you, the photographer, and, your desired results.
Select a larger aperture or as large of a aperture your lens is capable of… remember, a large aperture results in a narrower depth of field.
Get as close, as possible, to your subject… the closer you are to your subject… the increased amount of background bokeh
Focus on the subject or a part of the subject you want sharp (i.e., in portrait photography this usually means the eyes)
Separate your subject from the background… this will have a direct effect in the amount of background bokeh
Photography Bokeh Effect
So… let’s see some examples of bokeh at various aperture and focal length settings:
Liz f/4.0 – lens focal length 100mm – distance to subject ~ 6 ft
f/1.8 – lens focal length 85mm – distance to subject ~ 6 – 8 ft
As you can see from the above examples, the background in the image of Liz is slightly more focused (less of the bokeh effect) in comparison to Krista’s images. Let’s examine why… the distance to the subject of the above images is close to the same (~6 – 8 ft) and so is the lens focal length (85mm – 100mm). The significant difference is in the f/stop… the larger aperture opening of f/1.8 selected for the images taken of Krista has reduced the focal plane/depth-of-field causing an extreme out-of-focus effect. So why did I select different f/stops? Personal choice.
In the case of Liz’s image, I intended for the viewer to see the fall foliage and river while at the same time separating her from the background. For Krista’s images, I wanted to completely separate her from an uninteresting background.
This brings us to question #2: Why do we choose or want to incorporate the bokeh effect in photography? I am sure there are many opinions… and, there is no right or wrong but for myself, I feel it important not to use the effect as a crutch. Instead, I prefer to use bokeh as a tool, to tell a story, to capture an emotion or direct the viewer to the point in the image you wish for them to go. Below is an image of Sidney, deep in thought… a much easier emotion to capture, while separated from a very busy background.
As a final thought, there may be a time that you wish to include the elements of the background. Maybe there is an interesting wall, or door, or texture, that adds to the story you wish to convey to your viewers. Remember, in the recap of how to create the bokeh effect… point #5… separate your subject from the background. Instead let’s place the subject close to or right at the background. If we do this then it will be much easier to maintain sharpness throughout the entire image.
Something like this with Evan and Sarah:
So, pick up that camera (and lens) and take some photos. Enjoy the art of photography… it is a fabulous and creative medium to share your vision of the world.
Jeffrey W Burger is a high school senior, engagement and family photographer residing in Linden, MI.
All photos used in this article are the sole property of J W Burger Photography ©