Bokeh or Blurred background in photography is a term referring to out of focus area in an image. It makes viewer’s eye focus only on the subject in the frame making the entire composition strong and appealing. Especially in portraits, blurred background is a very important composition tool. In this post, I will try to describe camera and composition settings to achieve maximum blurred background.
Aperture – Higher the Better
A fast lens is a best suited for a highly blurred background. In photography, fast lens refers to a lens which can open wide open, like f/1.4 or f/1.8 or f/2 etc. A higher aperture can get us a very thin Depth Of Field (DOF) hence throwing the background (and foreground) out of focus. There are many online DOF calculator and mobile apps which can be used to calculate the exact DOF of any lens at given aperture. But we need to be careful when using a narrow DOF as it may render some parts of the subject also blurred, unless, we need that to use creatively. My Nikon 50mm 1.4G gives a sharp DOF and it is difficult to even keep both eyes of a person in focus.
A very cheap Nikon 50mm 1.8G lens (~200 USD) is a great choice for achieving amazing background blur. Lens which have aperture wider than f/1.8 are often expensive as they are costlier to make due to larger glass components. Nikon’s latest lens 105mm 1.4G (~2200 USD) is a bokeh monster. See samples from Nikon here.
Focal Length – Longer the Better
This is a very important and often neglected factor. A lens having a focal length greater than 85mm ~ 200mm is a wonderful tool to achieve a blurred background. On a longer focal length, even an aperture of f/4 or f/5.6 gives amazing background blur.
Shutter Speed and ISO – Does not Matter
Other camera settings like Shutter speed and ISO have no affect on how blur is the background in any images so these can be really ignored.
If you only have a kit lens (example – 18mm-55mm f/3.5-f/5.6) ; which is neither fast nor telephoto; you can play around with these composition techniques. These techniques will certainly help in getting more background blur.
Camera to Subject Distance – Closer the Better
DOF of any lens at fixed focal length and aperture is shallower when the distance to a subject is less. For example, a 200mm lens at f/2.8 has a DOF of only 0.03 feet when the subject is kept at 5 feet. While it is 0.12 feet when the subject is kept at a distance of 10 feet. As a result, try to keep the subject as close to the camera as possible to achieve maximum blur.
Subject to background Distance – Farther the Better
This one is no brainier. Farther your background is from your subject, more the background blur. Unfortunately, this may not be possible to achieve in-house.
Both above composition techniques when combined gives a higher subject to background distance ratio resulting in more blurred background.
Quality of Background Blur (or Bokeh)
Let’s talk about some technical stuff now. Bokeh, technically speaking, refers to the quality of background blur and not the background blur itself. But these terms are interchangeably used on the web these days. Bokeh is essentially a feature of aperture blades. A higher number of aperture blades creates more rounded lens opening resulting in a pleasing bokeh. Expensive lens have a higher number of blades, hence better bokeh. These days lens manufacturers are using rounded blades, which result in a perfectly rounded lens openings.
Some more bokehlicious Images to Inspire you