What Is Depth Of Field In Photography?

Depth of field is the distance between the nearest and farthest parts of a photo that look sharp. It decides what the viewer sees clearly and what dissolves into blur, which makes it one of the strongest ways you have to tell someone where to look.

In the petals above, the sharp zone is a few millimeters deep: one curled edge is crisp and everything else is soft. In a landscape focused carefully at f/11, the same sharp zone can run from a rock at your feet to the mountains on the horizon. Both are depth of field. You control which one you get with four things: the aperture, how far away you focus, the focal length, and how big the final picture is seen. This page explains why each one works, gives you real numbers for each, and shows how to choose.

Why only one distance is truly sharp

A lens focuses perfectly at exactly one distance. Picture each point of light in the scene sending a cone of light through the lens. For a point at the focus distance, that cone comes to a tip right on the sensor, and the point records as a point. For a point nearer or farther, the tip of the cone lands in front of or behind the sensor, so the sensor cuts through the cone and records a small disc instead. That disc is called a blur circle.

Blur circles near the focus distance are tiny. Your eye cannot tell a tiny disc from a point, so those areas still look sharp. Move farther from the focus distance and the discs grow until, at some point, you notice them. Depth of field is simply the range of distances where the blur circles are still too small to see. The largest disc that still passes for a point is called the circle of confusion.

Three things follow from this picture, and they explain almost everything else on the page:

• Sharpness falls off gradually. There is no wall where sharp turns to blurry. The edges of depth of field are a judgment about when blur becomes visible.
• A wider cone makes bigger discs. Anything that makes the cone of light wider (a bigger aperture opening) makes the discs grow faster as you move away from the focus distance, so the sharp zone gets thinner.
• “Visible” depends on how the picture is seen. A disc invisible on a phone screen can be obvious in a large print or a 100% crop. Depth of field is partly a fact about the lens and partly a fact about viewing.

One more distinction will save you a lot of confusion later. Depth of field is how deep the sharp zone is. Background blur is how big the blur circles of a far background are. They usually move together, but not always, and many online arguments about lenses and sensors come from treating them as the same thing. The quality of that blur, whether it looks smooth or busy, is a third thing again, called bokeh.

Wondering why some backgrounds melt smoothly and others look nervous and busy? That is the character of the blur, not its amount, and the bokeh page covers what shapes it.

The four controls, and how much each one moves the sharp zone

Try it before reading the details. The simulator below asks you to isolate a subject with a shallow sharp zone; change one setting at a time and watch what happens to the background.

Want the other challenges? The full camera simulator has all 21, across eight scenes.

Aperture: the control you can change without moving

The aperture is the opening inside the lens, and the f-number describes its size relative to the focal length. A low f-number such as f/1.8 is a wide opening and a wide cone of light, so blur circles grow quickly and the sharp zone is thin. A high f-number such as f/16 is a small opening and a narrow cone, so blur circles grow slowly and the sharp zone is deep. If f-numbers still feel backward, remember that they are fractions: f/16 means the opening is one sixteenth of the focal length.

Here is what that means in practice, for a subject 3 meters away on a full-frame camera (circle of confusion 0.03 mm):

Read across any row and each step to the next f-number in the table (about two stops) roughly doubles the depth or more. Read down a column and you see focal length matters a lot too, as long as you stay in the same spot. Changing the aperture also changes how much light reaches the sensor, so every stop you close costs a stop of shutter speed or ISO. That trade is the reason aperture priority mode exists: you choose the depth of field and the camera handles the rest of the exposure.

Focus distance: the control that costs no light

Depth of field grows roughly with the square of the focus distance. Double the distance and the sharp zone becomes about four times deeper; halve it and the zone shrinks to about a quarter. Distance is a big part of why the petals at the top of this page, shot from close up, have a sharp zone of millimeters at f/4.2, while a 50mm lens at f/4 holds most of a person 3 meters away.

Distance is also the control people forget. Stepping back costs no light and changes nothing in your settings. Stepping closer is the cheapest way to get a thinner sharp zone with a modest lens: a 50mm at f/4 focused at 1.5 meters has a shallower zone than the same lens at f/1.8 focused at 3 meters.

Focal length: real, but mostly because of magnification

From the same spot, a longer lens gives a much thinner sharp zone. Standing 3 meters from someone at f/4, a 24mm lens holds about 1.85 to 7.89 meters in focus, more than 6 meters of depth. Zoom to 70mm without moving and the zone shrinks to about 2.80 to 3.23 meters, roughly 43 centimeters. That is about fourteen times shallower, and it is the effect most people mean when they say long lenses blur more.

But that comparison also changes how big the subject is in the frame. Keep the subject the same size by walking back as you zoom in, and something surprising happens. Here is a waist-up portrait at f/4, framed the same way with three lenses, with a background 10 meters behind the subject:

With the framing locked, depth of field barely moves: about 60 centimeters with every lens. What changes is the background. The 85mm makes each background blur circle almost three times larger than the 24mm, and its narrower view shows a smaller slice of that background, so it looks smoother and more separated. That is the real reason a longer lens “blurs the background more” in portraits. The rule underneath is that at the same f-number, depth of field depends mainly on magnification, how big the subject is on the sensor. Focal length and distance are two ways of setting that magnification.

Wildlife photographers live at the far end of this. A 200mm lens at f/2.8 focused on a bird 8 meters away has about 26 centimeters of depth, enough for the bird and not much else, and a forest well behind it becomes soft texture. The distance from subject to background matters as much as the settings: the farther the background is behind the subject, the larger its blur circles get.

Is the “squashed” look of a long lens the same thing? No, that comes from where you stand, not from blur, and lens compression shows the difference.

Sensor size and viewing size: the hidden fourth control

The circle of confusion is not fixed by physics. It is a standard based on an 8 by 10 inch print (about 20 by 25 centimeters) seen from about 25 centimeters away. A smaller sensor has to be enlarged more to make that print, so its blur circles get magnified more, and the standard figure is smaller: about 0.03 mm for full frame and about 0.02 mm for the common smaller format with a 1.5x crop factor.

That gives two answers to “does a bigger sensor have less depth of field?”, depending on what you hold the same:

• Same framing, same f-number: the bigger sensor gives the thinner zone. Framing a subject at 3 meters, a 33mm lens at f/4 on the smaller sensor holds about 1.4 meters; the matching 50mm at f/4 on full frame holds about 0.9 meters.
• Same framing, f-number scaled by the crop factor: the two look the same. The full-frame 50mm at f/6 (f/4 times 1.5) holds about 1.3 meters, nearly identical to the smaller sensor at f/4.

Phones are the extreme case. Their sensors are so small, and their real focal lengths so short, that a typical phone main camera at f/1.8 focused 1.5 meters away keeps roughly 1 to 3 meters sharp, and focused at about 3 meters it keeps everything from about 1.6 meters to infinity sharp. The soft backgrounds in phone portrait mode are calculated by software from a depth map, which is why hair edges and glasses sometimes go wrong.

Shooting on a phone and want real separation? Portrait mode explained shows what the software does and where it fails, and shallow depth of field on an iPhone covers the tricks that work without it.

Viewing size works the same way. A photo that looks sharp front to back on a phone screen can show soft corners or a soft horizon in a large print, because the print enlarges every blur circle. If you plan to print big, judge depth of field at 100% on screen, or use a stricter circle of confusion in a calculator.

Put the four controls together in the tool below: change the aperture, focal length, focus distance and sensor one at a time, and watch which figures in the row stay sharp and how soft the hills become.

Where the sharp zone sits around your focus point

The sharp zone is never centered on the focus point. More of it always lies behind the focus point than in front, and how lopsided it is depends on how far you focus compared with the hyperfocal distance (explained in the next section, written H here):

The rule “focus a third of the way into the scene” comes from that middle row. It is a reasonable first guess for a medium-distance scene at a moderate aperture, but it is not a law. When you focus far closer than H, as in close-ups, the split is nearly even, so focus right in the middle of what you want sharp. As you focus nearer to H, more and more of the depth lies behind the focus point, so focus nearer than a third of the way in.

Hyperfocal distance: sharp from close up to the horizon

For any focal length and aperture there is one focus distance, the hyperfocal distance, that puts the far edge of the sharp zone exactly at infinity. Focus there and everything from about half that distance to the horizon looks sharp. Focus at infinity instead, which is what many people do with landscapes, and you throw away all the near sharpness between half the hyperfocal distance and the hyperfocal distance itself.

The formula is: hyperfocal distance = focal length squared divided by (f-number times circle of confusion), plus the focal length. Work in millimeters. For a 24mm lens at f/8 on full frame: 24 times 24 is 576; 8 times 0.03 is 0.24; 576 divided by 0.24 is 2,400; add 24 and you get 2,424 mm. Focus at about 2.4 meters and everything from about 1.2 meters to infinity is acceptably sharp.

Some full-frame values worth knowing, in meters, with the near limit always about half the figure shown:

The table shows why wide lenses are easy for front to back sharpness and normal lenses are not. A 16mm at f/8 gets everything from about half a meter onward; a 50mm at f/8 can only start sharpness at about 5 meters. If your foreground is close and your lens is long, you may not be able to get it all, and that is a sign to change position, change lens, or move to the methods further down.

Treat the hyperfocal distance as a starting point, not a guarantee. The 0.03 mm standard is generous by the standards of today’s high-resolution sensors and large prints. If the horizon matters, focus a little beyond the calculated figure, then magnify the shot on the screen and check both ends.

Want the numbers for your own lens and camera without the arithmetic? The hyperfocal distance calculator gives the focus point, and the depth of field calculator gives the near and far limits at any distance.

Compare the arch with the petals at the top of the page. One uses a small aperture and a distant subject to hold a whole scene together; the other uses a close subject to isolate a single edge. Neither setting is correct on its own. The right one is the one that matches what you want the viewer to look at.

Now try the arch rather than the petals in the simulator below: get the nearest rocks and the far horizon both sharp without going past f/16, using where you focus as much as the aperture.

When one aperture cannot give you enough depth

Closing the aperture further is not free. As the opening gets small, light spreads as it passes the edges of the blades, an effect called diffraction, and it softens the whole frame, including the part in focus. On most full-frame cameras the softening starts to show around f/11 to f/16 and becomes obvious by f/22; on smaller sensors it shows sooner. Past that point, more depth of field means less sharpness overall.

When you need more depth than a sharp aperture can give, you have three ways round it:

• Step back or go wider. Less magnification means more depth, then crop or accept a wider view.
• Focus stacking. Take several frames at a sharp aperture, each focused a little farther away, and blend the sharp parts in software. This is standard in macro work, where even f/16 gives only a few millimeters.
• Tilt the plane of focus. A tilt-shift lens lets you lay the plane of sharp focus along the ground instead of facing the camera, so a field of flowers and a distant hill can both sit in it at a moderate aperture.

Choosing depth of field for the picture you want

Start from what the viewer should see, then pick settings. Some starting points, all for full frame (on a smaller sensor, open up about a stop for the same look):

• Single portrait. f/2 to f/4 with a 50mm to 85mm lens. At 85mm f/1.8 from 1.5 meters the sharp zone is about 3 centimeters, less than the distance from nose to ears, so focus on the nearer eye. Read more on portrait photography.
• Two or more rows of people. Rows a meter apart need about a meter of depth. A 50mm at f/2 focused 4 meters away holds only 3.65 to 4.42 meters; at f/5.6 it holds 3.16 to 5.45 meters, enough for both rows. See photographing groups.
• Street and travel. A 28mm at f/8 focused at about 3.3 meters keeps everything from about 1.6 meters to infinity sharp, so you can shoot without waiting for autofocus. That is zone focusing.
• Landscape. f/8 to f/11 and focus at or a little past the hyperfocal distance, not at infinity.
• Wildlife. The widest aperture that keeps the whole animal sharp, and a background as far behind it as you can find.
• Close-ups. Accept that depth is millimeters. Line the important plane up with the sensor, so a flat flower face or an insect’s side sits square to the camera.

When you want a blurred background, you do not always need the widest aperture. Get most of the separation from background distance and focal length first, then set the aperture. Stopping down a little from wide open gives a bigger margin for focus error, sharper results from most lenses and room to keep both eyes sharp.

Two practical points catch almost everyone. First, the viewfinder or screen usually shows the lens wide open, not at the aperture you set, so it shows less depth than you will get. Use the depth of field preview button if your camera has one, or take the shot and magnify it. Second, focus peaking highlights edges that are in focus and gives you a fast look at where the sharp zone actually falls.

Which control caused the blur? Reading your own photos

When part of a photo is soft and you did not want it to be, work through these questions in order:

1. Is anything sharp at all? If nothing is sharp, depth of field is not your problem. It is camera shake, subject movement, or a missed focus. See how to take sharp photos.
2. Is something sharp, but not the thing you wanted? Focus landed in the wrong place. Look for the sharpest part of the frame, often the background behind a face, and use a single focus point next time.
3. Is the subject sharp, but parts of it are soft? The sharp zone is too thin. Close the aperture a stop or two, or step back a little.
4. Is the foreground sharp but the horizon soft, or the reverse? Your focus was in the wrong place for the depth you had. Use the hyperfocal distance, or focus stack.
5. Is everything slightly soft, even at the focus point, at f/16 or beyond? That is diffraction. Open up to f/8 or f/11 and use one of the methods above to get the depth.

Common mistakes and misconceptions about depth of field

• “A blurry background always makes a better photo.” A thin sharp zone hides context. Landscapes, groups, architecture and any picture about a place usually need more depth, not less.
• “Long lenses have less depth of field.” Only from the same spot. At the same framing and f-number, depth of field is nearly the same with any lens. What grows with a long lens is the size of the background blur.
• “Full frame always has shallower depth of field.” Only at the same framing and the same f-number. Scale the f-number by the crop factor and the two formats look the same.
• “The sharp zone is split evenly around the focus point.” It is nearly even only when you focus far closer than the hyperfocal distance, as in close-ups. Otherwise more of it lies behind the focus point, and at the hyperfocal distance all of the far side runs to infinity.
• Focusing landscapes at infinity. The sharp zone then starts at the hyperfocal distance instead of half of it, so you lose everything in between. Focus at the hyperfocal distance instead.
• Shooting at f/22 “for maximum sharpness”. Diffraction softens everything. On most full-frame cameras f/8 to f/11 is the best balance of depth and overall sharpness.
• Trusting the viewfinder. It usually shows the lens wide open. Check the actual picture, magnified.
• Forgetting the background distance. A wide aperture with the subject standing against a wall gives little blur. Move the subject away from the background.

Try this: one subject, three controls, ten minutes

Put a small object, such as a mug, on a table about 1.5 meters from you, with something detailed a few meters behind it, like a bookshelf or a fence. Use aperture priority, or on a phone use the main camera without portrait mode. A phone has a fixed aperture, so on a phone do step 2 only.

1. Aperture. Without moving, shoot the same frame at your widest aperture, f/5.6, f/11 and f/16. Focus on the mug every time.
2. Distance. At your widest aperture, take one frame from half the distance and one from twice the distance, keeping the same lens setting.
3. Framing locked. With a zoom, go back to twice the distance and zoom in until the mug is the same size as in your first frame. Shoot at the widest aperture you used before (if your zoom loses aperture as you zoom in, use the aperture it allows at the long end for both frames).

Judge the results on a big screen, side by side. In set one, the background should get steadily more detailed as you close down, and the f/16 frame may look a touch softer on the mug itself. In set two, the closer frame should have the softest background. In set three, the depth on the mug itself should look much the same in both frames, while the background in the zoomed frame should look softer and show less of the bookshelf. If you see that, you have seen with your own camera the difference between depth of field and background blur.

Questions about depth of field

What does shallow depth of field mean?

It means only a thin slice of the scene is sharp and everything in front of and behind it falls into blur, as in a portrait where the eyes are crisp and the background melts away. You get it with a wide aperture from a fast lens, a close subject, a longer focal length and a background well behind the subject; it is a form of selective focus. Its opposite, deep depth of field, keeps a whole landscape sharp from near to far.

Is depth of field the same as bokeh?

No. Depth of field is how deep the sharp zone is. Bokeh is what the out of focus areas look like, smooth or busy, round or cat’s eye, and it depends on the lens design. Two lenses at the same settings can give the same depth of field and very different bokeh.

What aperture gives the most depth of field without losing sharpness?

On most full-frame cameras, f/8 to f/11 gives deep focus with little diffraction softening. Past about f/16 the whole picture starts to soften. For more depth than that, step back, focus at the hyperfocal distance, or focus stack.

Why is my background still sharp at f/1.8?

Usually because the subject is far from you, the background is close behind the subject, or both. Move closer to the subject, put more distance between subject and background, or use a longer focal length while keeping the same framing.

Does focal length affect depth of field?

From the same spot, yes, strongly: a longer lens magnifies the subject and thins the sharp zone. At the same framing and f-number, depth of field is nearly the same with any lens, but the longer lens blurs the distant background more.

Where should I focus to get the most front to back sharpness?

At the hyperfocal distance for your focal length and aperture, which makes everything from half that distance to infinity sharp. If you have no calculator to hand, focus a little in front of your main distant subject rather than at infinity, then check the shot magnified.

Why do phones keep everything in focus?

Their tiny sensors use very short real focal lengths, so at normal distances the sharp zone is deep even at f/1.8. The blurred backgrounds in portrait mode are added by software rather than created by the lens.

Ready to check what stuck? Try the aperture and depth of field quiz, or the hyperfocal distance quiz if you want the harder questions.