Bokeh – what is it?

Bokeh is one of those words that have newcomers to photography scratching their heads! Their confusion is made worse by the way that the word is misused by many authors and bloggers who should know better.

The Japanese word “bokeh” is usually pronounced with bo as in bone and ke as in Kenneth, with equal stress on either syllable.  It is often defined as the way a lens renders out-of-focus points of light. In general, some lenses render it in a more pleasing way than others.

OK, so what do we mean by “pleasing”? Well, you can easily spot “bad” bokeh. The out-of-focus areas of a picture will have a feeling that could be described as gritty, clumpy or wiry. These areas tend to draw the eye and detract from the picture, especially if they contain bright highlights or are in the foreground. Have a look at this or this. Warning – some of them may hurt the eyes.

“Good” bokeh on the other hand is often described as smooth or creamy. There is little to distract the eye from the parts of the image that are in focus. Out of focus highlights will be rendered smoothly without harsh edges. Often they will be circular, but will sometimes be a polygon whose number of sides depends on the lens diaphragm (frequently seven or nine-sided). Try some random examples – this or this or this.

The real problem with bad bokeh is that once you are aware of it, it draws the eye and can’t be ignored.

How can I get better bokeh?

There are articles and even books that imply that you can control bokeh. You can’t. What you can control is depth of focus, and anyone who has been on the Reflex beginner’s course will know how you can do that:

  • Lens aperture
  • Distance from the camera to the subject
  • Distance from the subject to the background

If you are aware of the rules and are still suffering from bad bokeh, what can you do about it? Use a different lens! There are some well-known rules of thumb:

  • Prime lenses usually give better bokeh than zoom lenses. Some zooms are really good for bokeh, but they tend to be large and expensive.
  • So called superzooms (with a zoom ratio of 10x or so) will generally have bad bokeh.
  • Very wide aperture lenses (e.g. F/1.2) can sometimes render very strange bokeh when wide open. They usually improve when stopped down but that rather destroys the point of them!
  • You usually get what you pay for. Cheap primes like the well-known brand 50mm F/1.8 lenses often have poor bokeh. That’s not to say they are not worth buying but it’s worth bearing in mind.
  • Mirror lenses have disastrously bad bokeh: highlights are rendered as bright doughnuts!

As always with rules of thumb, there will be exceptions…