Have you been wondering what this Bokeh, that most pro’s talk about, is? It is actually the misspelling of a Japanese word if you take it in a literary sense. The real spelling is Boke and its a Japanese word meaning Fuzzy. OK don’t wonder where your friends learned Japanese from. Photography has a lot to do with Japan and there are a lot of Japanese pro’s this word was commonly used by them to explain the fuzzy areas and its quality. Now an English writer writing for an English magazine made it bokeh which is the way it is pronounced.
To explain Bokeh we need to understand DOF or Depth Of Field. DOF has two measurements one is the distance of the Focused area from the lens the second is the depth of the area in focus. The first is called DTF depth to field and the second is DOF or depth of field. To understand this two concepts the image below should help. The camera has three butterflies in front of it.
These are divided into three regions the not in focus area in front, the area in focus and the area not in focus at the back. Now anything that is in the Depth of Field area will be considerably sharp and will be the area of interest in the photo. The area in front and behind this region will be blurry.
Bokeh refers to this blurry area. Now why all the fuss about this blurry area , is it not blurred ? Lets understand bokeh in further detail. Let us understand that the quality of bokeh is subjective, but the subjectivity is due to the fact that there is difference between bokeh produced by different lenses.
The characteristics of a given lenses bokeh is analyzed by looking at the circle of confusion. Circle of confusion is the (blurry) spot that is produced by a (definite) spot that is out of focus in the image.
Now the circle of confusion has a lot to do with the shape of the aperture. That is the shape of the circle of confusion is determined a lot by the shape of the aperture. Lenses depending on their build quality have different type of aperture. That is in short aperture shape is not a circle. It is more like a polygon than a circle. The best bokeh have circle of confusion that is defused or has no sharp edge.
Better quality bokeh gives the image a more pleasing look. Bokeh comes into question only when a short DOF is used when a large DOF is used most of the field is in focus and there is no blurry component to have a bokeh. In short DOF applications mostly we intend to give the object in focus importance, depending on the application we might want or not want the onlooker to have attention on the area that is blurry. The type of bokeh usually helps us in doing this.
Some more expensive lens allows the photographer to control the bokeh. Though a useful feature you might be better off paying for more aperture or constant aperture than paying for bokeh control.
Most of the retouching software have options to create artificial blurr and along with it tools to control the bokeh of the blur thus created.
The quality of an image is greatly improved with the look of the bokeh. Next time you are out purchasing a lens do look at the bokeh the lens creates. The quality of the same can make or break you picture bokeh.
This image shows circle of confusion distinctly towards the mid right. If you expand the image (by clicking on it) you will notice that these circles are not diffusing but rather are quite sharp towards the edge which shows a low quality bokeh, but if you look at it further you will notice that the circles being noticed give a better look to the image all together. The purpose of the image was to make you understand what is circle of confusion how to rate them and most importantly that the quality of bokeh is subjective. Depending on the way you photograph, one type of bokeh might suite you better than another type.
So decide for your self what type of bokeh you like and would complement your work. Also look around on the net for images taken using the particular lens you are interested in. Flickr or other such social photo sharing platforms could be of great help in this endeavour. Even with point and shoot cameras you can look around for images to understand their capabilities. Mostly point and shoot cameras don’t have small DOF and thus bokeh doesn’t count at all, but there are some higher end version where bokeh counts.
There is another interesting thing to note about bokeh, you could actually give shapes to it. This is done by using a very small aperture and a cutout of the same size(to avoid vignetting), the cut out is put in front of the lens and the shape of the cut our becomes the shape of the circle of confusion. This can be used to create very interesting images.
The image on the left shows a heart shaped bokeh. This is created by using a card board with a small heart shaped hole cut in it. This is then place in front of the camera’s lens. The aperture is set to a similar, in fact a little larger size.
So next time you buy a lens do check out the bokeh it produces. Also do give importance to the bokeh your current lens produces.