11 September 2011

Bokeh for Beginners

It is one of those words bandied about by photographers and it is too often assumed that people actually know what is meant when someone says that they love the bokeh of a particular shot. No need to reach for the dictionary later, looking for the definition of bokeh. Here is a brief guide to bokeh for beginners.

Let’s go along with the Do-Re-Mi song from The Sound of Music and start at the very beginning: the word itself. It doesn’t look English and it most certainly doesn’t sound English. You would be forgiven for thinking it sounded like it was the latest Kabala-like craze sweeping the nation, maybe some sort of odd skin condition (‘ew, look at the bokeh on that kid’) or the name of one of the transformers. The word is Japanese in origin and literally means a haze or a blur. In Japanese the ‘h’ at the end is not present – it seems to have been adopted in English speaking circles to help with the correct pronunciation. If you say boke-aay then you are pretty close.

You have probably guessed by now that it is all about focus. Yes, but of course there is a little more to it than that. Who exactly coined the word in terms of photography and for the English speaking world (not to mention the added h) is hotly debated but the forerunner is one Mike Johnston who used to edit the Photo Techniques magazine. Boke had been in use in photographic circles from the mid nineteen nineties. The word with the added letter has been seen in print since at least the turn of the new century. Do not, then, feel as if you should have known this word already. In terms of the English words, it is very new. How marvelous it would have been, though, if Shakespeare had coined the word. “The quality of mercy is not bokeh”.

One of the big differences between photography and other forms of art such as painting or drawing is the issue of focus. When we, as humans, regard the world then our eyes see everything in front of us in focus, whether it is near or far. Historically that is how artists have mostly reflected that world back to us. Even though the person or object at the front of the canvas may be produced using sharper colors and more detail, the objects which were intended to be less prominent were generally still produced as the eye would see them.

If you do it purposefully, however, your eye can haze out the less important of those things that you see in front of you. The photographic lens can de-emphasize parts of an image, whether at the front, the near field as it is known or in the background. Different lenses on different cameras have varying success in this technique. Cameras with large aperture lengths are particularly adept at catching out of focus bokeh. Those with small aperture lenses usually simply soften the photograph.

The foreground and background of an image can be controlled by the F-number (one of a number of things admittedly). The F stands for Focal. Focal length is determined by how strongly a lens converges or diverges light, or in other words how much it focuses or defocuses it. The F-number is the focal length divided by the size of the aperture of the camera. The larger aperture creates a blurrier background.

However, bokeh is not just science and mechanics – it is also about aesthetics. Bokeh is defined by many not so much in terms of how blurred the background (or indeed foreground) is but how pleasing the overall effect of the blur is. When you appraise bokeh you should always ask yourself how pleasing the haziness is to your eyes.

The quality of an image can be enhanced with bokeh as it makes the subject of the photograph leap out of the picture and forces the human eye (with its focus on everything) to concentrate on that part of the photograph – indeed, that which the photographer wishes them to look at. Bokeh is hugely important for macrophotographers to capture and emphasize the detail of the tiny object being captured. What are the blurs behind the giant dead dandelion above? A tree in a field, of course. Yet bokeh makes the image front of field all the more attractive as it is so very much the focus of our attention.

Bokeh could almost be called a trick of the eye in some sense as it does effectively force the eye to focus on one are of an image rather than another. One could say that about virtually any photographic technique, however, from tilt shift to Chiaroscuro. Confused? Well, you are going in the right direction because it is all to do with something called the circle of confusion. This is a spot which a cone of light rays from a lens creates when it does not come to a ‘spot on’ focus when creating an image. When an area is out of focus then it becomes an image of the aperture. Most lens apertures are polygonal and that is why when you see bokeh, the shapes in the picture are generally similarly shaped. However, if you keep your camera set to its maximum aperture size then bokeh should appear circular.

The lens is all important in the creation of bokeh. The discs in bokeh can be illuminated uniformly. Alternatively they can be brighter near the radius or brighter near the center. This is all dependant on the spherical aberration of the lens and how it is corrected for it. This is an effect that happens when the refraction of light through the lens is increased. In ‘normal’ photos this would be an aberration, but in bokeh it is up to the individual photographer. In other words, the photographer may alter the camera settings so that the spherical aberration is poor to achieve his or her desired effect.

Of course, there is always the school of bokeh for bokeh’s sake.

Some argue that another Japanese word should join the English language lexicon. That word is pinto. It means in focus and it is pronounced ‘peen-toe’. Effectively, then, anything in an image that isn’t pinto is (or can be argued to be) bokeh. As the meerkat says, simples (British joke).

Ultimately the appreciation of bokeh is completely subjective. It is entirely up to whether you think an image fails or succeeds because of bokeh. To recap though, if asked what it is you can get away with saying that it the out of focus part of an image and in particular the characteristics of that part. Whether you like it or not, however, is always and completely up to you.