What Is Depth Of Field? Definition And Examples.

Published: June 18, 2024 | Last Updated: June 19, 2024

Depth of field means how much of an image is in sharp focus from front to back. If you have a shallow depth of field, only a small part of the image is sharp, while the rest is blurry. This is often used in portraits, commercials, and interviews to keep the subject clear and the background soft. The soft background is also known as bokeh. A deep depth of field means that most or all of the image is in focus, which is common in landscape photography, nature documentaries, and cinema to keep everything from the foreground to the background sharp.

Several factors influence the depth of field in an image, including:

Aperture: The size of the lens opening through which light enters.
Camera-Subject Distance: The physical distance between the camera and the subject.
Focal Length of the Lens: The distance between the lens and the image sensor when the subject is in focus.
Sensor Size: The dimensions of the camera’s image sensor.

Let’s break each one down in more detail below and see how each affects the field depth.

Aperture Adjustment

How aperture is related to the depth of field

When adjusting the depth of field, you can adjust the aperture, expressed in f/stops on photo lenses and t-stops on cinema lenses. The aperture size controls the amount of light entering the camera and influences the image’s sharpness.

Large Aperture (Low f-stop/t-stop): Allows more light, resulting in a shallow depth of field and more background blur. This is ideal for isolating a subject, such as in portrait photography.

The effect on aperture on the depth of field — **Example 1:** The effect of the aperture on the depth of field when the focal length remains the same. You must compensate with your camera’s ISO to achieve the same brightness in each image. See the section below about the exposure triangle.

Of course, landscape photography doesn’t automatically mean that everything needs to be in focus. Sometimes, you want to focus on something in the foreground or the background, like in the examples below.

Shallow Depth of field landscape photography example — ***Example 2:*** *Here, I focused on the almond trees in the foreground to highlight their silhouette and how the light from the setting sun illuminated the rim of the leaves. This is also a shallow depth of field.*

Depth of field background focus example — **Example 3:** Here, I focused on the setting sun, which also created a shallow depth of field with the trees and mountains in the foreground and middle ground out of focus.

Small Aperture (High f-stop/t-stop): This setting allows less light, resulting in a deep depth of field and greater sharpness throughout the image. It is often used in landscape photography.

To ensure satisfyingly sharp objects in the foreground (fx a flower) and background (fx distant mountains), you need to know the hyperfocal distance, which depends on your lens, sensor size, and aperture.

See how to calculate the hyperfocal distance.

Landscape photography hyperfocal distance example — **Example 4:** If you know the hyperfocal distance, you can ensure that objects in the foreground, middle ground, and background are all sharp.

When a lens is focused at the hyperfocal distance, everything from half that distance to infinity will be in acceptable focus. In this context, depth of field can be defined as half the hyperfocal distance to infinity:

Depth of field and hyperfocal distance — *The depth of field defined in relation to the hyperfocal distance.*

The Exposure Triangle

The aperture setting works with shutter speed/angle and ISO to achieve the desired exposure and focus. This interdependency can be illustrated with the exposure triangle:

A large aperture may require a faster shutter speed to prevent overexposure, while a small aperture may necessitate a slower shutter speed to allow sufficient light.

Increasing the ISO can compensate for reduced light from a small aperture, which may introduce noise into the image.

Camera-Subject Distance

The distance between the camera and the subject also influences the depth of field. When the camera is closer to the subject, the depth of field becomes shallower, isolating the subject from the background.

Moving the camera further away deepens the depth of field, incorporating more of the background into focus:

Distance and depth of field example — **Example 5:** I’ve changed nothing on the camera or lens. I just moved closer to the garden windmill.

Focal Length of the Lens

The focal length of a lens determines its field of view and magnification. Lenses with longer focal lengths (telephoto lenses) generally produce a shallower depth of field, while shorter focal lengths (wide-angle lenses) result in a deeper depth of field.

Focal length and depth of field example — **Example 6:** I’ve changed the focal length from 13mm to 25mm, not the distance or aperture.

Size of the Camera Sensor

Camera lens sensor size and depth of field

The size of the camera’s sensor also affects the depth of field.

At the same aperture settings, larger sensors (full-frame or medium format) produce a shallower depth of field than smaller sensors (APS-C or micro four-thirds).

This is because the larger sensor captures more light and detail, affecting the overall depth of the image.

Summing Up

You can control the depth of field by manipulating the aperture, camera-subject distance, focal length, and sensor size. Increasing the depth of field results in sharper images, while decreasing it creates a blurred background (aka bokeh) that can isolate subjects.

Using a shallow depth of field to keep the subject in focus while blurring the background can draw the viewer’s attention to the subject. This is great for portraits, interviews, and product commercials.

A deep depth of field can keep the entire scene in focus. This is great for landscape photography, establishing shots, and scenes where you want to capture everything that happens in the background – such as sitcoms or action sequences.

Depth of field can also convey emotions. A shallow depth of field can evoke intimacy and focus, while a deep depth of field can create a sense of vastness, inclusion, or feeling lost and isolated.

Up Next: The most common lenses and focal lengths used in movies.

What is Depth of Field? Definition and Examples.