Bokeh is not a term that is commonly used in ordinary language. The term is rather associated to photography, so if you’re new to photography, then you may not be familiar with bokeh. What is bokeh and how does it work?
To understand bokeh a bit better, without risking over explaining it, have you noticed a photo with the subject on focus and the background out of focus? Take a closer look at the out of focus background, if the quality of the background, or if the background has smooth or rather rough edges, than that is what is called bokeh.
In photography there are two types of bokeh, good and bad. Good bokeh is when the out of focus or blurred background has smooth edges. Bad bokeh is when the blurred background has rough edges. However, depending on the type of effect you are going for, a bad bokeh maybe something that you want. This means that good and bad does not necessarily refer to their meaning but just a description of the two types of bokeh.
The Smaller the Aperture Number better the Bokeh
The quality of bokeh you can create relies on the quality of the camera lenses that you have. Higher quality lenses, with maximum aperture 2.8 or below will be able to create a smoother bokeh. For example: NIKKOR 85mm f/1.4G . If you really can’t afford to buy high quality lenses for now, don’t worry. You can still create bokeh, not just as smooth.
In order to create bokeh, you will need to adjust your aperture settings for a shallow depth of field. This means that the object is in focus but the back ground is out of focus. This effect makes the viewer of the photo focus on the object rather than the background.
You will not be able to create bokeh if you have your aperture set for a wide depth of field (bigger aperture number) . This is because the whole photo will be in focus.
In order to control the quality of bokeh you create, practice with different aperture settings for a shallow depth of field. However, keep in mind that you will want to capture the entire target and the only parts of the photo you want to be blurred is the background.
The Longer the Focal Length the better the Bokeh
Tele lenses (70mm an above) produces better Bokeh than wide angle lenses (35mm and below). Thats why lenses like, Canon EF 85mm f/1.2 L is called bokeh king. Just check the example on that page.
The closer you get to the subject the better Bokeh you get
Another thing to keep in mind is that bokeh will also be affected by the distance of the background from the target. When practicing bokeh at different aperture settings, make sure that you change the distance of the target from the background as well.
When you do this, you can get a feel of how bokeh is affected not only by aperture settings but by background distance as well.
Shape & number of Aperture blades controls the Nature of bokeh.
An five Blade aperture diaphragm will produce a pentagonal bokeh with a recognizable shape. As the number increases for example: 8/9, bokeh effect become more circular shape & smoother. Results great bokeh. Same way curved shaped blades produces better & smoother bokeh.
Bokeh provides a very cool effect on your photograph is used properly. There will be situations where you would want to create a bad bokeh effect and a good bokeh effect just won’t do. In order to recognize what these situations are, you will need to do a lot of practice with bokeh. Take plenty of photographs of different objects at different locations under different lighting conditions and you will find out what situations will require you to use a bad or good bokeh effect.