Focus on Bokeh

20 October  2014

amended 30 August 2016

Photographers today refer to Bokeh more than before. The term itself attributed to the phenomenon is relatively new. But the things change. In particular, the tools we use, of which we have more in the first place, are generally more advanced and they are also getting more differentiated. And the photography as a whole has continued to evolve and further differentiate.

So let’s have a look at the Blur. What that has to do with the photograph?

As the blur in the picture is related to the depth of field, the less of DOF during the capture, the more of the blur is becoming its part. Larger DOF reduces blur to barely noticeable traces, though it always is more noticeable in larger prints, whereas the shallow DOF exaggerates it making it additional feature in the photo, influencing the way its content is formed and rendered.

What place has the blur in the photograph?

The blurred sections in the image are often simply part of the photo, but they can also gain more important role, especially when they are part of a deliberate effect that has a direct relationship with the subject in focus or when they become a visually significant part of the image.

The blurred, out-of-focus parts of the image point to some converging links between the way we look at these features and our own way of visual and mental perception of the world. Generally, the convergence notices two different principles that become very alike in resulting shape, behaviour or response despite them being quite different in their essence. It is often demonstrated in biology and evolution. Here, the subject isolation, the peripheral perception of the blur rendered in a photo and the way of seeing these things in our daily lives are similar. After all, in both cases, optics and the mental picture are working for the end percept. The subject isolation effect in a photograph is a familiar experience to us and is similar to the way we perceive our world around us. And the blur rendered in a photograph is gaining a particular role for the picture.

Subject isolation

It happens when the subject is in focus and the other parts of the image are out-of-focus (blurred) exactly the same way as it happens when we focus our eyes on a subject and the difference in distances to the subject and to other objects included in the field of our sight is great enough for the effect to show and especially to become perceivable. The camera can create this effect visually (if not mentally) more prominent and we can focus on both features more (or completely) independently so they now have become powerful and distinct features in a photo.

The way we perceive through our own eyes and brain can be considered more complex but here we focus on the photograph and similar media like the painting, where the 3D way of seeing is compressed within a 2D picture. The photograph can do remarkably well in the area that is otherwise reserved for more sophisticated systems. Another strength of the photograph is doing this its own, very specific way, and that is further enabled by the development of tools like lenses and materials (like in printing). 


When the blur next to the subject in focus intensifies, the rendition of the objects ‘in the background’ changes and the features of the objects are modified as they become more abstract and sketched. They don't necessarily become less real by this to us but the language of the picture changes the way it speaks to us and that is the deliberate aim. By becoming blurred the features take on a new form and they enter the realm of contours, become more schematic, simplified and symbolic.

Character of the Blur

plays a vital part in the role the blur can convey the content the desired way. In that respect, photographers refer to it as to the quality of the blur. This quality has gained significance among them as the lenses vary not only in the degree they can blur out of focus areas but also what the blurring looks like and how the rendition is valued.

That has its own typical criteria and one of the most important ones is rendering of out-of-focus details in a way that isn't distracting but is either neutral or in some way harmonising with the subject in focus.

The intensity of the blur is one factor and the character of the blur another. It is these two together that influence the rendition of the ‘background/foreground' part of the scene and while the first is more of a technical sort (and of a varied intensity and gradualness) the later gives the blur its own, aesthetically specific imprint for every single lens. The role of the bokeh for the picture and its quality by its nature is subjective and in the overall assessment of the lens often tied to other things like colour, sharpness, other contrast-based renderings, tonality, colour temperature and other important characteristics.

The bokeh’s character itself and the intensity of the effect for a given shot can become a subject of intense debates. The mainstream idea of a smooth, soft bokeh that is showing less edge definition or artefacts on high contrast elements in the photo and that is rather blur-intensive (strong effect) is generally prevailing view. Although the existence of hundreds of lenses (also so-called legacy lenses) and the variety of unique characters among them specially favoured by the photographers break a firmly established pattern. This is understandable once trying to realise the number of possible expressions and their potential for subjective views. It has a direct effect on how the blurred parts of the scene are rendered and its quality and character can provide and enhance context for the subject and the parts that render sharper as they are more in focus. The interactions between in-focus and out-of-focus parts are then letting us be more creative and reflect better our own perception. And although the large DOF photograph remains a powerful and fundamental concept in picture taking, the variety of the blur effect, its applications and variety of the bokeh rendition itself bring an additional element of individuality to the process. It allows us to express more of the inner and individual via the photo and refine the image for the desired characteristics, personal style and the intent.


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