What is depth of field and why is it so important?

Technically speaking, depth of field is the portion of a scene that appears sharp in the image. Never mind what kind of photo you want to take you want to have total control over depth of field.

To understand the depth of field better we need to divide an image into 3 parts.

These parts or elements of the image are subject, foreground, and background. Subject is what the main point of interest that you want to capture is. Foreground is everything in front of the subject and background is everything behind the subject.

To get all these parts of the picture in focus it would require you to have a very large depth of field. Usually we want a large depth of field when we are shooting landscapes.


On the other hand, there are occasions when you don’t want a whole picture in focus. You would want that, whenever you need your subject to stand out of the picture and avoid a cluttered background that steals attention away from the main subject.

If you only wanted to have the main subject in focus and have the foreground and background out of focus that would require a shallow depth of field.

How can you change depth of field?

You can change the depth of field by changing the aperture on your camera. Smaller apertures yield images with more depth of field and wider apertures yield images with shallower depth of field.

This means that whenever you want your main subject in focus and the background out of focus, you need to open the aperture wide. This is done by lowering the f-stop number.

On the other hand, whenever you want a whole picture in focus, you need a smaller opening. You can achieve that by raising the f-stop number.


If you want to learn more about aperture, read this article that explains the aperture in more details.