Background blur aka bokeh. It’s the creator of moods, the teller of stories, and the hallmark of a professional portrait photo.
But how do I get a sharp subject with a blurred background or vice versa, you may ask?
In three easy steps: use a +35mm focal length, get up close, and go wide open on the aperture ring.
Why Blurry Background?
First of all, photos that have blur in them come across as more natural/realistic.
Furthermore, when the subject is razor-sharp against a blurred-out background, the two get separated from each other.
This is why you’ll hear the phrase ‘background separation’ a lot. Conversely, when both are equally in focus, they blend together.
Try holding your hand as close to your face as the eye can focus while keeping the background as far away as possible.
Notice how everything except your hand gets blurred out?
We overlook this effect due to constantly being exposed to it.
A blurred background can look pleasing and help create a certain mood and feeling in the shot.
Factors That Affect Background Blur
The higher the maximum aperture setting of the lens, the more blur it can produce. While the overall image can become too soft at maximum values, there is an easy fix.
Stop up one or two clicks to achieve better center sharpness while keeping the rest blurry.
Distance Between Background and Subject
The further the background is from the subject, the more significant the difference in sharpness.
This is particularly easy to notice outdoors, but experienced photographers have it as second nature to be aware of and modify the background — a lot.
Naturally, the focal length of your lens also plays a dramatic role when it comes to blurry backgrounds.
In particular, from 50mm and up, there is a massive difference. While 35mm and 24mm can get decent bokeh, it usually requires getting up close.
Distance Between Camera and Subject
Some fairly wide lenses have super short minimum focus distances. This lets us get into the near-macro territory and get some nice, dreamy bokeh — even on a wide-angle lens.
No matter what lens you use, distance to subject alters the amount of bokeh. Also, sensor size plays a role here too. The larger the sensor, the better bokeh potential.
Background Blur Quality
Not all blur is created equal. Sometimes, it has erratic patterns and harshness. Otherwise, it can be smooth and dreamy or even swirly.
Several technical factors like optics and the number of aperture blades affect the bokeh quality.
Depth of Field and Bokeh
High aperture = low depth of field. When working with a small aperture value like f/1.8, only a thin ‘slice’ of the image is in focus. Anything before or after it – stays blurry.
Try aiming the lens along the pavement. Now observe the effect by manually sweeping through the focus range.
Camera Settings to Blur the Background (or Subject)
You might be thinking, ‘alright, this makes sense — but how do I actually get a sharp subject with an out-of-focus background?’
Easy peasy, here’s how:
Your camera probably has a macro mode (often represented by a tulip symbol). Using this mode enables getting as close as possible to the subject and blurring out the background.
AV or Manual Mode
AV is short for Aperture Value. Perhaps you are confident enough to shoot in full manual. If not, AV mode is perfectly OK and won’t disqualify you as a photographer.
Simply dial in the wanted aperture setting, and the camera adjusts the ISO and shutter speed for correct exposure.
Combine macro mode with AV priority and get the most amount of bokeh possible.
How to Blur the Subject and Get a Sharp Background
Simply reverse the technique and focus on the background, to get it crisp and sharp, with a blurred-out subject.
Other factors still apply — distance, focal length, and aperture setting.
Creating Blur in Post
Perhaps your lens doesn’t go wide enough, or there is no room to create enough distance between the subject/model and the background.
If so, then there is one last resort: editing in the blur during post-production.
This can, of course, be achieved in Photoshop. But there are also many intuitive mobile apps (including PS Express) that let you blur out any part of the image in a few taps.
You can effortlessly get gorgeous bokeh in the image using the proper focal length and aperture setting.
Factors like the distance between the lens, subject, and background also impact the amount of blur.
The technique works similarly for blurring out the foreground or subject.