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What is Depth of Field?

Today we’re going to break down Depth of Field (DoF) in photography. Today, my friends will be the final day you will scrunch your eyebrows in confusion when someone starts talking about “shallow depth of field.” After today, you’ll be able to look at them with confidence, hold your shoulders high and mighty and say “ total cake.” That right there friends, that’s some real confidence. Buckle up.

Note: From this point forward, we will be shortening “Depth of Field” to just “DoF”.

What is Depth of Field (DoF)?

In photography, “DoF” is the technical term used to describe how much of the photo is in focus. And it’s DoF that allows us, as photographers, to determine what areas we want in focus in our photos. It’s the main tool used to either draw attention to or away from, specific areas of the photo or to the entirety of the photo, which is your choice to make.

Simply said, it’s how wide the field of focus is in an image. The Field of Focus being the distance from the point originally focused (Point of Focus), compared to the front and back edges of focus.  When focusing on a subject or object, DoF determines how much of that subject is in focus from the Point of Focus to the Field of Focus based on the Aperture setting selected. And how great the distance between the specific point you focus on and Field of Focus, both in front of and behind that point, is completely within your control.

Note: DoF is not affected by whether or not you’re focusing using autofocus or manual focus. However, a more shallow DoF will affect how easily it is to focus in both modes, especially when manual focusing.

How do we increase or decrease Depth of Field?

So then, since DoF can be controlled, how do we actually go about changing it? You mentioned this whole Aperture thing before, how does that work?

Yes yes. That’s exactly how it works. DoF is either increased or decreased by adjusting the Aperture of your lens. The larger the aperture setting of your lens, which is commonly referred to as “stopping down” a lens,  the greater the DoF in your image.

While, on the other hand, DoF can be decreased by reducing the Aperture of your camera or lens. And this is commonly referred to as “opening up” a lens.

This also means that as Aperture increases, the more in front and behind the specific focus point will also be in focus. And the exact opposite is also true.

Note: manual focusing only lenses have aperture settings directly on the lens themselves and cannot be controlled through the camera.

Think: larger number (Aperture) =  larger DoF

So wait… what happens when you have a larger DoF?

A larger DoF really just means that more of the subject and background are in focus. Nothing more to it than that really. And how much will be dependant on how close or far you are away from the subject

What happens as Aperture changes?

As we mentioned above, Aperture refers to the size of the opening of the lens.  Smaller Apertures (bigger numbers) means larger DoF’s. This means that as Aperture increases, so does the distance of the Field of Focus. And the Field of Focus only becomes larger and larger with each added step in Aperture.

The exact opposite is also true, where a larger Apertures (smaller numbers) means a smaller (more shallow) DoF’s. The value you see for Aperture, commonly known as “F-Stop” in your camera is the technical notation for how much DoF an image will have.

What are the (3) main ways to control Depth of Field?

The main ways to control DoF are:

  • The lenses Focal Length
  • Distance from the subject
  • Aperture (F-Stop) set in the camera

The focal length of your lens determines how wide or narrow your field of view will be. Simply said, a wide angle lens has larger viewing angles than a telephoto lens. When shooting with a wide angle lens, since the viewing angles are larger, the DoF even at lower values will still be greater than a telephoto lens.

This is because each lens have different viewing angle, and the relative distances when shooting wide angle lens makes objects from the foreground, midground and background appear the same relative distance to each other. And objects at the same relative distance will be similar in focus. And because of this, with wide angle lenses, you will generally get more narrow (or a greater) DoF compared to a telephoto lens, even with the same amount of light, same exact settings and distance from the subject.

DoF between different focal lengths will all be different because focal length directly affects DoF. So with that, know an Aperture of F4 isn’t the same across every lens. Macro, Wide Angle, Midrange, and Telephoto lens will all have different affects on DoF. If you want more shallow DoF, shoot with longer focal length lenses.

Note: the same applies if you’re shooting with a zoom lens versus a fixed focal lens (know as a prime lens). At more wide zooms, DoF will be greater, while at more narrow zooms DoF will be more shallow. Generally, a prime lens will have significantly more shallow DoF compared to a zoom lens zoomed at the same focal length. The next thing that affects DoF is your distance from where you are to where the subject is.

Whenever you’re closer to subjects, DoF is going to be more shallow. This includes even higher Apertures as well. And just know that moving closer to subjects will also decrease DoF making it more shallow, to some degree. The degree it does will depend on how close you can get to the subject. This is why it is especially difficult to shoot Macro photography because there’s so much magnification and the relative distances are so much larger.

Lastly, DoF is a function of the actual F-Stop value set in the camera or on the lens itself. As mentioned before, a smaller number means that the lens is more wide open and thus a smaller DoF. For example F1.8 vs F11. Since 1.8 is smaller than 11, the DoF for F1.8 will be smaller than F11 when a photo is taken of the same subject and at the same distance.

Note: the shutter speed does not affect the DoF, only Aperture will. And DoF is not affected by sensor size. So, whether you’re shooting with a crop sensor APS-C camera or a Full Frame sensor camera, it won’t make much of a difference on that front.

What’s the purpose of Depth of Field and why is it important? 

The purpose of DoF is for you as a photographer to be able to make a creative decision on how much you want and what you in focus when shooting. Before approaching a shot, consider how much you want in focus of not only the subject but the background as well.

For example: do you want only the subjects facial features to be in focus and then everything from their ears on backward to be out of focus? Do you want the whole subject to be in focus? Do you want some parts of the subject to be in focus and also some, but not all, elements in the background to be in focus? All of these questions will help you determine prior to even setting up the shot what Aperture will be needed to get the desired result you want.

So that then raises the infamous question, how do you get an out of focus background or background blurring, commonly known as “bokeh?” If you want a more shallow background, reduce your Aperture down to the lowest your lens has available. For example, if you were shooting a 50 mm 1.8 F lens, you would set the lens to 1.8. That’s the easiest way to get a more shallow DoF. You can also do the same thing by moving in closer to your subject, then slowly increase your aperture to get the elements of the subject that you want and focus but also get more shallow background blur.

What are the types of Depth of Field?

There are two types of DoF, the first being shallow and second being narrow. Shallow DoF being Apertures below F2.8, typically. And more narrow DoF being Apertures greater than F8.0 typically. Shallow DoF has Bokeh or background blur, while Narrow will have most, if not all, of the image in focus.

Tips on getting the Depth of Field you want!

When shooting landscape photography where you want everything in focus in the image, set your aperture to the maximum value allowed by your lens, typically F22, so that both your foreground and background are in focus. Now if shooting with a wide angle lens, set your Aperture to the middle of the range and shoot at F8 to F11, so that will give you the sharpest images. Typically, most lenses are manufactured so that they’re actually sharpest in the middle of their ranges. So a lens that goes from F1.8 to F22, would actually be sharpest around F8-F11.

Note: the lens used will determine both the maximum and minimum Apertures available for use, which would then determine your DoF. And each lens will have different DoF’s.

Note:You can find more information on your specific lens by doing a quick search online for the lenses model number followed by DXOMark sharpness and looking at the measurements page for each F-Stop value.

When shooting portraits, both inside and outside, start with an Aperture of F4.0, then go either up or down in Aperture depending on how much of the subject you want in focus. If you want a lot of background blur, set your leans to the lowest Aperture available (F1.8 or below), but make sure to focus on the eyes since everything else will more than likely be out of focus.

When shooting fashion and beauty photography, set your Aperture to F8 to F11. This allows there to be a large enough DoF so that the entire model is in focus, but not enough for all of the background to be.

Last Updated on May 7, 2023 by Photography PX Published July 9, 2019