Hyperfocal Distance and Depth of Field - Everything You Need to Know

In this episode of Photo Myths, I sit down with pro photographer Richard Bernabe, and together we tackle an oft-repeated photo rule, which states that to get sharp focus throughout the image frame, you should "focus one-third of the way into the scene."

I hear this one all the time. In the video below, Richard and I explain why this is a total photo myth.

In the video, Richard and I discuss hyperfocal distance, depth of field, and a bunch of other stuff related to this idea of "sharpness" in photography, but we don't take too deep of a dive into the topic. Frankly, it's confusing even to advanced photographers. If you really want to learn more, then keep reading—but don't say I didn't warn you!

Circle of Confusion

Whether an object in a photo appears to be sharply in focus or not is determined by something called—and I’m not making this up—the Circle of Confusion. Here’s a definition from Wikipedia:

In optics, a circle of confusion is an optical spot caused by a cone of light rays from a lens not coming to a perfect focus when imaging a point source. It is also known as disk of confusion, circle of indistinctness, blur circle, or blur spot. In photography, the circle of confusion is used to determine the depth of field, the part of an image that is acceptably sharp.

Without realizing it, you’ve just stumbled into an unholy collision of optics, physics, and lots of ridiculously complicated math. You’ve descended into the Tenth Circle of Hell, reserved for photographers who can’t take sharp photos.

I’m not a science and math whiz: I just take pictures. Frankly, I don’t understand any of this technical stuff. But like me, you don’t need to understand it in order to make intelligent choices about focusing for your photos.

Plane of Focus

When we talk about focus, we often use the phrase “focus point,” but this is misleading. Actually, a more accurate way to think about it is as a focus plane. I don’t mean an airplane, but rather “plane” as in “a flat surface.”

The plane of focus is a two-dimensional plane in front of the camera at the point of focus, and it is always parallel to the camera’s sensor. So, if you are photographing a wall in front of you that is completely parallel to your camera sensor, if you focus on any part of the wall, all of the wall will be in focus because the wall is entirely in the plane of focus. It is important to note that the plane of focus remains in the same position relative to the sensor plane, so if you tilt your camera up or down, the plane of focus will tilt with it. Going back to the wall example, if you tilt your camera down while photographing the wall, the top and bottom of the wall will be in different planes of focus.

"Sharp" Focus

Okay, I’ve been using phrases like “sharp focus,” but that isn’t exactly correct.

Focus isn’t like a light switch that’s either on or off. Instead, whether something is sharp or unsharp occurs as a gradual transition. Anything that is in front of or in back of the focus plane begins to immediately lose sharpness, although this decline in sharpness might not be perceptible. At some point, however, we begin to notice, with the appearance of sharpness declining the further away you get from the focus plane. This is where the whole “circle of confusion” things comes in, which is an effort to quantify when something begins to appear unsharp to the human eye.

As you might have already guessed, this injects a huge amount of uncertainty into the process. Don’t be fooled by all the math and science: all of this stuff is built on a rather shaky foundation of subjective human visual perception! This is nothing that you need to worry about for now. I just wanted to share this basic premise: we’re not really talking about bringing a scene into sharp focus. Instead, we are seeking to bring the entire scene into “acceptable” or “apparent” sharpness. In other words, we are looking to make sharpness seem good enough that most people won’t notice.

Of course, this apparent sharpness might vary considerably depending on your final reproduction size; if you are only posting photos in small resolution on the Internet, it is easier to make everything look sharp than if you are making a really big print to hang on your wall. In other words, the larger the eventual reproduction size, the more precise you need to be when setting focus.

Hyperfocal Distance

Hyperfocal distance is a confusing concept, involving a lot of mathematical formulas, making the whole thing seem ridiculously complicated. But without a basic understanding of hyperfocal distance, you will find it difficult to adequately ensure that all parts of the image frame are acceptably in focus. Here’s what Wikipedia has to say on the subject:

In optics and photography, hyperfocal distance is a distance beyond which all objects can be brought into an "acceptable" focus. The hyperfocal distance is the closest distance at which a lens can be focused while keeping objects at infinity acceptably sharp. When the lens is focused at this distance, all objects at distances from half of the hyperfocal distance out to infinity will be acceptably sharp.

Wow. Got that? I’m not surprised if you didn’t. Let’s see if I can simplify the discussion.

Basically, hyperfocal distance tells you where to focus your lens. But when it comes to making sure everything in your picture frame is acceptably sharp, the definition of hyperfocal distance is misleading: simply setting the lens to the hyperfocal distance won’t ensure sharp focus from near to far in your composition. Hyperfocal distance doesn’t act alone; instead, it works in conjunction with depth of field, which extends your apparent zone of focus in front of and behind your chosen focus point. How much depth of field you have is determined (mostly) by your choice of aperture.

Depth of Field

Depth of field is another ridiculously confusing yet vitally important concept for you to understand (sorry for all the confusing stuff—it just comes with the territory). Depth of field can be thought of as a "zone of sharpness" around the focus point. Here’s Wikipedia’s definition of depth of field:

Depth of field (DOF), also called focus range or effective focus range, is the distance between the nearest and farthest objects in a scene that appear acceptably sharp in an image. Although a lens can precisely focus at only one distance at a time, the decrease in sharpness is gradual on each side of the focused distance, so that within the DOF, the unsharpness is imperceptible under normal viewing conditions.

Several factors affect depth of field, including camera-to-subject distance, lens focal length, sensor size, and the selected lens f-number (or aperture).

Aperture and F-stops

Every lens has a variable aperture that lets in light to the camera sensor. The aperture consists of multiple blades arranged in a circular array that work together to increase or decrease the size of the aperture opening (thus changing the amount of light passing through). An f-stop or f-number describes the size of the aperture opening. Once

again, we turn to Wikipedia for clarity:

In optics, the f-number (sometimes called focal ratio, f-ratio, f-stop, or relative aperture) of an optical system is the ratio of the lens's focal length to the diameter of the entrance pupil.

Yeah, that helps.

So, here’s why f-stops matter for photography, and why you need to roughly understand how they work: the f-stop determines depth of field, which, as you know from the previous section, determines how much of the scene appears to be in focus. Remember that circle of confusion thing I mentioned at the beginning of this article? Well, your f-stop changes the size of the circle of confusion, thus either expanding or contracting your depth of field as a result. But ignore all that: all you need to know is that smaller f-stops such as f/22 and f/16 produce lots of depth of field, while larger f-stops such as f/2.8 or f/4 produce less depth of field.

Determining the Hyperfocal Distance

Essentially, hyperfocal distance tells you where to optimally set your focus so that you may extend depth of field over the entire scene. So, how best can you determine the proper place to focus for a photo? Remember, hyperfocal distance is defined as “the closest distance at which a lens can be focused while keeping objects at infinity acceptably sharp. When the lens is focused at this distance, all objects at distances from half of the hyperfocal distance out to infinity will be acceptably sharp.”

Let’s turn that definition upside down to make things easier. To find the hyperfocal distance (or at least something that sufficiently resembles the hyperfocal distance that it is good enough for us to work with), all you have to do is focus on a point that is twice the distance from the closest object in your composition.

For example, let’s say your composition includes flowers in your foreground that are three feet away. To focus on the hyperfocal point, all you need to do is set your focus to six feet. Don’t worry about making precise measurements, as this method is designed to be (1) close enough to be reasonably effective, (2) easy to work with in the field, and (3) achievable with a minimum amount of thought (which is extremely useful when working in fast-changing lighting conditions). By the way, depth of field doesn’t spread out evenly around your focus point; as it turns out, most of it is behind your focus point, which is why the hyperfocal distance tends to be so close to the camera.

Easy, right? The hard part is that this method doesn’t really tell you anything about what aperture to use. Don’t worry, I’ll cover that next!

Choosing the Correct Aperture

Subject distance should be considered first. If your subjects are all far away, then you don’t have to worry about depth of field as much as when you have both near and far subjects. For example, if everything in your photo is at infinity, then you don’t really need any depth of field at all.

But near-far compositions, where you have something close by in the foreground and a background at infinity, will need a lot of depth of field to get everything in focus. Your focal length will also impact how much depth of field you have, and it is easier to get extreme near-far depth of field with a wide-angle lens than it is with a long telephoto. Smaller sensor sizes also have more depth of field, making it easier to get everything in focus even with larger apertures.

Also keep in mind that the closer you focus, the shallower your depth of field (that's why macro photographs often feature extreme selective focus). With extreme near-far compositions, your hyperfocal point may end up being very close to you, requiring a smaller aperture to make everything in the scene appear to be acceptably sharp.

That said, you should avoid whenever possible using your smallest apertures. Even though very small apertures can produce extensive depth of field, an optical defect known as diffraction limits the overall appearance of sharpness. Diffraction is most apparent when you are using your lens' smallest apertures. If you need the depth of field, then by all means, use those small apertures, but if you can get by without them, your photos will look sharper as a result.

For most of my near-far compositions, I end up using f/11 or f/16 to ensure sharp focus throughout the image frame. Selecting the correct aperture is the hardest part of this whole thing. Unfortunately, there aren't any easy guidelines you can follow. You'll have to use some trial-and-error to get comfortable with choosing the correct aperture, and even then, it still involves a fair amount of guesswork.

One way to determine if you have the correct aperture (and therefore the correct amount of depth of field) and you are focused in the correct place is to zoom into 100% when reviewing the photo. Scroll through the foreground and background parts of the image, and if everything looks sharp, you're good to go. If the foreground or background are out of focus, then you can try moving your focus point or selecting a smaller aperture. Keep trying until everything looks sharp.

Focus Stacking

One way to take all of the guess work and subjectivity out of the process is to do what is called focus stacking. This involves taking a focus bracket, keeping everything else the same (exposure, composition, etc.) and just moving the focus point for each separate image in the bracket, starting with the nearest part of the scene until you reach the farthest point. Then, you blend the images together on the computer using a focus stacking program like Helicon Focus. Focus stacking is typically easy to do, and it ensures a sharper image.

I discuss focus stacking, as well as other creative focus techniques, in my Creative Focus Course (PRO members can access the course here as part of their membership).

Conclusion

I know this hyperfocal distance and depth of field stuff is confusing, but every photographer needs to understand these concepts at a basic level. Sure, focus stacking can make this all seem obsolete, but there are times when focus stacking isn't an option (such as when there are moving objects in your composition, or you are working in fast-changing light and every second is precious).

If you understand hyperfocal distance and depth of field, you'll be able to get the apparent sharpness you need, no matter what the conditions are like.