First off, what is Bokeh? To simply put it, Bokeh is just a term used to describe a photo with a blurred background. In fact, the literal meaning of Bokeh in Japanese is "blur". You've probably seen Bokeh used in Christmas photography, where Christmas lights in the background are blurred to appear as colorful orbs. You can actually see this exact effect used in one of the photos for our earlier posts for the release of 12 Days of Gifts.
Bokeh is controlled by three factors: 1) the aperture (the size of the opening in a lens to let light in); 2) focal length; and 3) distance. Without getting too technical, you will want to use these three factors to achieve a shallow depth of field which refers to the area that is in focus.
Let's start by observing what happens if you shoot an image with a wide aperture like f1.4. In this situation, the main subject is the sphere. Focusing on the sphere sets the focal distance but, since a wide aperture has a very shallow depth of field, neither the pyramid nor the cube will be included and therefore appear blurred.
This time, by maintaining the focal distance and reducing the size of the aperture to f5.6, we notice the depth of field widens. Widening the depth of field results in all three objects being included, meaning they all appear in focus once the photo is taken.
However, this is not necessarily how an iPhone works. Generally current smartphones ship with a fixed aperture.
In this situation we have opted for a new subject and a background. Since an iPhone has a locked aperture, we don't have the freedom of controlling the depth of field. In this example our subject is the cube so as usual, tap to focus to set the focal distance. However, notice how the background is now also included inside the depth of field and will appear in focus if we take a picture. So how do we overcome this? It's actually quite simple.
First of all, we want to try limiting the focal distance as much as we can. This means bringing the subject as close to the camera as possible before your iPhone can't focus on it anymore. Of course this will also depend on how large your subject is, but try to stay close. Because the aperture is locked, the depth of field remains relatively similar. So to blur the background, all you have to do is push it back as far as possible and that is where the third condition - distance, comes into play.
Here is a photo that I took a while ago with an iPhone 5 applying the same concepts mentioned above. This photo is straight from the iPhone's camera with no post-processing.