Bokeh, which refers to the aesthetic quality of the blur in the defocused parts of an image, is an expression technique that is unique to photography. It can give depth to an image, and is essential means of drawing attention to a subject of focus. In this article, we shall explore 4 important factors in creating bokeh, and find out how to control the bokeh effect created so that it appears as intended. (Reported by Tomoko Suzuki)

 

4 important factors for creating visible bokeh

 

There are four factors that play a part in the visibility of the bokeh effect (i.e., the degree of defocusing in the intended area): Aperture, focal length, shooting distance, and distance between subject and background. Using the right combination of these factors as appropriate for the subject and scene will help you create a bokeh effect that looks just the way you intended.

Aperture: The larger the aperture (the smaller the f-number), the more visible (“larger”) the bokeh effect and vice versa
Focal length: The longer the focal length, the more visible the bokeh effect and vice versa.
Shooting distance: The nearer the subject, the more visible the bokeh effect and vice versa.
Distance between subject and background: The further away the background, the more visible the bokeh effect and vice versa.

In other words, to get the most obvious bokeh possible, you would need to use a telephoto lens, set it to maximum aperture, move closer to the subject until you are the minimum shooting distance away, and choose shooting location/position where the visible background is as far away from the subject as possible. However, simply creating the most obvious bokeh possible does not work for every photo. It is important to adjust the bokeh effect so that it suits the objective and intent of the photo—and this ability to adjust is an essential photographic skill.

Let's take a closer look at each of the factors influencing bokeh visibility.

 

Aperture

The examples below were shot from the same position, but with different apertures. At a large aperture (f/1.4), the background is obviously defocused (very visible bokeh effect), whereas at a small aperture (f/16), the entire image is in focus, including the background. This is because at a large aperture, the depth of field is shallow, which causes the background to be out of focus.

 

Focal length

The following images were both shot at f/2.8, but at different focal lengths. They were framed such that pillar with the name appears to be the same size in both images. At 70mm, the background bokeh effect is quite visible, but at 24mm it is significantly less obvious. This means that when you use a zoom lens, you will get a more obvious bokeh effect when you use a longer focal length.

 

Shooting distance

The examples below were shot at the same aperture (f/1.4), but from different shooting distances. You can see how the distance between the camera and the subject affects the visibility of the bokeh effect. When the camera is closer to the subject (the 50cm example), the background is more defocused and the bokeh effect is more visible. When the camera is further from the subject (the 70cm example), the background is more in focus and the bokeh effect is less visible. Do note that how close you can get to the subject depends on your lens’ minimum shooting distance (also known as its 'closest focusing distance').

 

Distance between subject and background

The following examples were both shot at f/1.4, but with different distances between the subject and the background. When the background is further away from the subject (60cm), the bokeh effect is more visible; when the background is nearer the subject (30cm), the bokeh effect is less obvious. This shows that if you want an obvious bokeh effect, you would want to make sure the subject is further away from the background.

 

Important things to note when creating a bokeh effect

1. Choose an aperture that retains adequate context in the image

The larger the aperture, the more intense the blurring and the larger the area of defocus. Of course, this draws more attention to the main subject, but if you create more blurring than is necessary, you would end up cutting out essential information that creates context in the image, such as the location and surrounding conditions. Consider how you want to portray your main subject of interest and choose your aperture appropriately.

 

2. To harness the power of suggestion, use a larger aperture

Using a small aperture puts everything in the image frame in focus. With elements so visually concrete, it becomes hard to suggest ideas and evoke images. Therefore, if your photo is intended to be more evocative than documentary, feel free to use a larger aperture and create a more visible bokeh effect. Doing so will help direct your viewers’ attention to where you want it to be, and give a clear idea of what it is that you want to show them.

 

The bokeh effect can help you achieve photos like this!

EOS 700D/ EF-S55-250mm f/4-5.6 IS STM/ FL: 127mm (203mm equivalent)/ Aperture-priority AE (f/5, 1/500sec)/ ISO 100/ WB: Auto

A long focal length and maximum aperture to create the optimum bokeh effect
This was shot at a long focal length (203mm in 35mm film equivalent), at the maximum aperture of f/5. I used two of the factors for visible bokeh to create a bokeh effect that blurs the details in the sea to draw attention to the seagull.

 

For more information on bokeh, check out the following articles:
Portrait Photography Techniques Using Bokeh
Improve Your Travel Photos with the EOS M10 #1: Using Bokeh to Isolate Subjects
Lens FAQ #8: Where Should I Focus On to Capture Beautiful Bokeh Circles?
Photographing Flowers: How to Create Brilliant Bokeh Circle Spotlights with a Macro Lens

 

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