Depth of field is a very important thing you can do to make your renderings more realistic. Almost every real photo has it. Even if you take a picture with your smartphone, it focuses on something. Sometimes you hardly notice it. But it’s always there.
Blender`s camera has depth of field built in. Just scroll down to the “Depth of Field” tab and set the “Iris” to “F/Stop” and set the F/Stop number as you like to get the result you want. If you do not want to use an empty slider, you can simply set the Distance slider.
Focus length is not always needed, but sometimes it can really help rendering. The higher you set it, the further an object looks. Each camera lens has a set focus length. By default, Blender’s Camera is set to 35mm, which is a good preset. It is a very common focus length. But not ideal for many situations.
In this article we won’t go further into different focus lengths as this would go beyond the scope. You will find many interesting articles on this subject on the Internet.
The one-third rule does not exactly contribute to realism, but it certainly improves quality, so let us include it anyway.
The one-third rule has existed since about the 18th century and it is still as useful as it was then. The third rule basically divides the picture into nine equal parts and then you place the main focus of the scene on one of the four middle corners.
Under this tab Blender has a third control in the camera settings.