The subject of shallow depth of field and the search for bokeh come up almost on a daily basis on the internet, if not sooner. This conversation often starts as a result of someone posting a portrait where the lens was shot wide open, be it f/1.4 through f/2.8. This is closely followed by a statement by another photographer saying something like, “the subject isn’t in focus”. Now we go down the bokeh rabbit hole. For those not familiar with the term “rabbit hole”; Metaphor for the conceptual path which is thought to lead to the true nature of reality. Infinitesimally deep and complex, venturing too far down is probably not that great of an idea.
First, a bit of history about the term bokeh.
The term comes from the Japanese word boke (暈け or ボケ), which means “blur” or “haze”, or boke-aji (ボケ味), the “blur quality”. The Japanese term boke is also used in the senseF of a mental haze or senility. The term bokashi (暈かし) is related, meaning intentional blurring or gradation.
The English spelling bokeh was popularized in 1997 in Photo Techniques magazine, when Mike Johnston, the editor at the time, commissioned three papers on the topic for the March/April 1997 issue; he altered the spelling to suggest the correct pronunciation to English speakers, saying “it is properly pronounced with bo as in bone and ke as in Kenneth, with equal stress on either syllable”. The spellings bokeh and boke have both been in use since at least 1996, when Merklinger had suggested “or Bokeh if you prefer.”The term bokeh has appeared in photography books as early as 1998. It is sometimes pronounced /ˈboʊkə/ (boke-uh). (as quoted from https://en.wikipedia.org/wiki/Bokeh). Since those first references to boke or bokeh the concept has become a near religion for some photographers. (Note: I personally dislike the term and its use not because I dislike the concept or the quest but because of many misunderstanding about it by many photographers, new and experienced.)
Now that we have that out of the way, let’s go into the rabbit hole.
I, like so many others, enjoy being able to separate my subject from the background unless that background enhances my subject. Many times, in portrait photography we chose a background that can be chaotic if it is in focus. This is where the quest begins, which I often liken to the hunt for the Yeti. This quest becomes even more challenging when we don’t understand or misunderstand what we are seeking.
Bokeh is more than just blurry. Bokeh refers to the quality blur, smooth creamy without hard edges and soft almost circular “points of light”. As a result, this doesn’t mean you have to open up to the widest aperture to achieve this look. I equate this with yoga pants, just because you can doesn’t mean you should.
Understanding depth of field
Before we can begin our quest for the Yeti, bokeh, we need to understand depth of field. There are two major players in depth of field, aperture and focus distance to the subject.
The key is to understand the relationship of two elements of depth of field. Those elements are aperture and distance to the subject. (There are other factors but these two have the most influence on depth of field)
Given any aperture and the aperture remains constant, the closer we are to our subject the shallower our depth of field. For example, if I am using my Nikon D750 (a full frame camera) with a 50mm f/1.8 lens opened up to f/1.8 and I am 10 feet from my subject I have a total depth of field of 15.4 inches, 7.2 inches in front of my focus point and 8.2 inches beyond my focus point. If I move in to 4 feet from my subject I have a total depth of field of 2.4 inches, 1.17 inches in front of my focus point and 1.23 inches beyond my focus point.
Using the example above, if I focus on the tip of a person’s nose at f/1.8 with a 50mm lens from about 4 feet away their eyes will most likely fall outside the depth of field and become blurred.
Does this mean we never shoot wide open? Absolutely not. This means we must determine what is important to have in focus and what is not.
Stop chasing the Yeti
Until you fully understand these basic concepts my advice is to stop chasing the Yeti (bokeh). You will sacrifice the importance of your subject and the Yeti will still be elusive.