How Does Aperture Affect Depth of Field?

Photo of author
Written By Nate Torres

As you become more experienced in photography and venture into photography’s technical intricacies, you will learn how aperture (one of the components of the exposure triangle), affects the exposure in your images as well as the depth of field.

Well in this article, we’ll be exploring aperture’s relationship with depth of field.

I’ll be diving into the definitions of aperture and depth of field, how aperture affects depth of field, other factors that influence depth of field, and lots more.

Let’s dive in!

What is Aperture?

Aperture is often referred to as the “eye” of your camera and plays an integral component in controlling the amount of light that enters your camera and reaches your image sensor.

Similar to how the iris of human eyes expand or contract to regulate the flow of light, the aperture in your camera lens performs a similar function.

Aperture is measured in f-stops, denoted by numbers such as f/1.4, f/2.8, f/5.6, and so on.

These f-stop values represent the ratio of the lens’s focal length to the diameter of the aperture opening.

The smaller the f-stop number, the wider the aperture, and vice versa.

aperture photography chart
aperture (f-stop) chart

For the most part, your lens aperture setting affects two critical factors in your image, the exposure (how overexposed or underexposed your image can get) and the depth of field.

This leads us to our next section.

What is Depth of Field?

The depth of field refers to the range of distance in a photograph that appears sharp and in focus.

A good way I like to think of it is the interplay between your subject or focal point and the surrounding elements that adds a sense of dimension, depth, and realism to your images.

You can either choose to isolate your subject and add a dreamy blur bokeh effect, or capture a sweeping landscape in crisp detail.

The depth of field is influenced by various factors (I’ll touch on those other factors later), with aperture being one of the most significant.

As mentioned in the previous section, when you adjust the aperture/f-stop, it will affect the size of the camera opening, impacting the depth of field in your photograph (along with exposure).

How Aperture Affects Depth of Field

The relationship between aperture and depth of field can be likened to a delicate dance, where subtle adjustments yield impactful effects in your images.

As mentioned earlier, aperture, which is the opening in your camera lens that controls the amount of light entering the camera, plays a crucial role in shaping the depth of field.

It’s important to know that aperture and depth of field have an inverse relationship — meaning that the wider the aperture (a smaller f-stop value like f/1.8) then the more shallow the depth of field, and the more narrow the aperture (larger f-stop value like f/16) then the more narrow the depth of field.

Let’s take a closer look at this inverse relationship.

Wide Aperture and Shallow Depth of Field

A wide aperture (represented by a smaller f-stop number like f/1.4 or f/2.8) creates a shallow depth of field.

In this scenario, only a small portion of your image—often the subject—remains sharply focused, while the background and foreground gently blend into a pleasing blur.

Shallow depth of field is commonly used in portraiture, headshots, or product photography, as it allows the subject to stand out against a soft, bokeh-filled background, drawing the viewer’s attention to the person or object of interest.

So for example, to capture this kind of image, I usually set my camera focus setting to single-point focus. You then put the focus point on your subject and make sure they are a good distance from the background.

Once you take the photo you’ll see that the subject is in focus and the background will be blurred.

shallow depth of field portrait
shallow depth of field portrait

Narrow Aperture and Deep Depth of Field

A narrow aperture (represented by a larger f-stop number like f/11 or f/16) results in a deep depth of field.

In this case, a larger portion of the scene—from foreground to background—appears in sharp focus.

This technique is often employed in landscape photography or street photography, where the desire is to showcase intricate details from near to far, immersing the viewer in the breadth of the scenery.

narrow depth of field landscape
Image by Geoffrey Werner

Other Factors that Influence Depth of Field

While aperture is a key factor in controlling depth of field, it’s essential to recognize that other elements also come into play, shaping the visual impact and focus within your photographs.

Understanding these additional factors empowers you to have greater control over depth of field and create images that align with your artistic vision.

Let’s explore some of the other factors that influence depth of field.

1. Focal Length

The focal length of your lens affects depth of field.

Generally, shorter focal lengths (wider-angle lenses) tend to have a deeper depth of field, meaning a larger area appears in sharp focus.

In contrast, longer focal lengths (telephoto lenses) tend to produce shallower depth of field, isolating the subject from the background.

2. Distance to Subject

The distance between your camera and the subject also plays a role in depth of field.

When you get closer to your subject, the depth of field becomes shallower, emphasizing the subject while blurring the background.

Conversely, increasing the distance between your camera and the subject can result in a deeper depth of field, bringing more elements into focus.

3. Sensor Size

The size of your camera’s image sensor influences depth of field.

Cameras with larger sensors, such as those found in full-frame or medium format cameras, tend to produce shallower depth of field compared to cameras with smaller sensors, such as those found in most entry-level DSLRs or smartphones.

Final Thoughts

In summary, when it comes to manipulating the depth of field without affecting the composition of your photo, making adjustments to the aperture remains the optimal choice.

Its ability to selectively control focus and blur, coupled with its minimal impact on exposure, empowers you to shape the visual narrative of your image while keeping the intended composition intact.

Frequently Asked Questions

Why does aperture affect depth of field?

Aperture affects depth of field because it controls the size of the lens opening, determining how much light enters the camera and subsequently impacting the range of distance that appears in sharp focus in the resulting image.

What aperture is needed for deep depth of field?

A narrow aperture, represented by a larger f-stop number, such as f/11 or f/16, is needed for deep depth of field, allowing a larger portion of the image to be rendered sharply in focus.

Do you want high or low aperture for shallow depth of field?

A low aperture, represented by a smaller f-stop number, such as f/1.4 or f/2.8, is desired for shallow depth of field, creating a narrow range of sharp focus and a beautifully blurred background.