How to get background blur in photography
- February 21, 2019
- by
- Alexia
One of the first things I wanted to do when I bought my first camera was the background blur (or bokeh). I share with you in this article the technique for making a beautiful background blur.
At the same time as you read the article, I advise you to bring your camera and find a subject (decorative object, toy ...) to take a picture to practice.
But… what is the depth of field?
The depth of field is the area of the image in which objects are sharp, it is the sharpness area.
When the blur behind the subject is pronounced, the depth of field is said to be shallow (or reduced). Conversely, when all the elements are sharp on an image, the depth of field is said to be large.
How to create a background blur?
To make a beautiful creamy background blur you have several parameters to take into account:
- The aperture
- The focal length
- The distance of the background from the subject
- The distance of the camera from the subject
Here is a picture, where no particular settings have been applied. We will add settings as we go along in this picture to get our background blur. You can do the steps at the same time as me to practice.
By the way, I would like to introduce you Axel the Pelican who kindly agreed to pose for me:
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| Settings: 1.25s, F/11, 17mm |
The aperture
If you have read the article in the exposure triangle, you have understood that the aperture is used to manage the amount of incoming light as well as the distribution of blur and sharpness in the image.
To create a background blur, you have to open your diaphragm, so set the aperture to small values (f/1.4, f/2.5, f/3.5...). The blur takes up much more space and the sharpness area becomes smaller.
As shown in this diagram, the more you open the diaphragm and therefore lower the number after the F, the more you will get this famous blur.
Let's take our test photo again with an aperture at f / 2.8 (my maximal aperture).
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| Settings: 1.25s, F/2.8, 17mm |
The maximum aperture is indicated on your lens:
The notation 17-70mm 1: 2.8 - 4 means that the maximum aperture of the lens when I zoom at 17mm is f/2.8, and at 70mm it is f/4.
The focal length
The focal length is what you certainly call: the zoom. It is expressed in millimetres (mm). I can say that at 200mm I zoom in a lot, at 10mm I zoom out a lot. The longer the focal length (zoom), the shallower the depth of field.
Basically to create background blur you need to... Zoom in to the maximum! So here I'm going to zoom at 70 mm.
Let's zoom on our picture as much as we can:
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| Settings: 1.15s, F/4, 70mm |
The distance of the background from the subject
It seems logical that if you focus on an object at, let's say, 50cm, if there is a wall just behind it, that wall can't really be blurry. To really get a blurry background, the background must be as far away as possible from the object on which you are focusing.
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| Axel is 1 meter from the background |
The distance of the camera from the subject
The last parameter that affects the blur is your distance from the subject.
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| On the first picture, I am 20cm from the subject. On the 2nd I'm at 1m. |
Detach a subject from the background
I also tested these settings on a real person. You can see that the background blur can be used to isolate your subject from the background. The eye will immediately be drawn to this clear area and forget everything that is blurry.
Here, the background blur is important. You can see that in the first picture Lisa is not demarcated. In the 2nd picture, people are blurry, so our eye is focused on Lisa.
What to remember
Phew, that's a lot of notion all of a sudden, isn't it? I propose a short summary of the parameters that affect the depth of field:
· The larger the aperture (= a small f), the shallower the depth of field.
· The longer the focal length (zoom), the shallower the depth of field.
· The further away your background is from your subject, the blurrier this background will be.
· The closer you are to the subject, the shallower the depth of field.
With all these settings combined, you should be able to create a beautiful background blur!
Depth of field is a complex concept, I myself had trouble understanding everything at once. I hope this article will help you to better understand your choices in your settings.
Of course, if you have any questions, don't hesitate to post a comment. 😉
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This is a good post. This post gives truly quality information. I’m definitely going to look into it. Really very useful tips are provided here. Thank you so much. Keep up the good works. background remover
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