Name: Photography Tutorial - Depth of field explained (shallow vs deep)
Uploaded: 2025-08-03T18:36:29.000Z
Duration: 10 min 12 s
Description: Thousands of YouTube videos with English-Chinese subtitles! Now you can learn to understand native speakers, expand your vocabulary, and improve your pronunciation...

It doesn't matter what kind of grand creative ideas you have if the part of your image that should be in focus ain't in focus.

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Now you might say, isn't it also like that with exposure and composition?

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Not necessarily, because exposure and composition can be altered in post-production.

If an image is out of focus, you can't fix it.

Now before you say, but there are sharpening tools in my image editor.

No, sharpening tools don't restore focus.

This is why I've been so adamant about keeping track of shutter speed and autofocus while you're shooting.

A slow shutter speed puts you at risk of blurring camera shake, and if you're not keeping track of what your camera's autofocus is doing, you won't necessarily get what you want in  So, having said all of that, we're now going to look at the concept of depth of field, which lets you ensure that some parts of your image will be out of focus.

When you're creating an image, your job as a photographer can be boiled down to a single task to control the viewer's eye when they look at your photo.

It's a visually complicated world out there, and you're trying to capture a representation of part of it.

Within that representation, you're trying to make certain that the viewer looks at specific things and sees them in a particular way.

Every technical and creative decision that you make serves that one goal.

Now, you have a lot of tools for doing that.

You can compose in a particular way, you can expose in a particular way, and you can focus in a particular way.

When you're exposing, you can, for example, plunge shadows into complete black so that there are no distracting details.

Depth of field gives you control over focus, and the simplest example is one that we've all seen a lot, a portrait.

Here is a portrait with deep depth of field.

That is, everything in the background is sharp and in focus, as is the subject.

So you might think that this is a successful portrait because everything is in focus, and as he said, focus is the most important thing.

Here's the same portrait shot with shallow depth of field.

The background is blurrier, but my subject is still in focus, and that defocused background is a way that I've grabbed the viewer's eye and made sure that they look at the subject rather than the background.

Depth of field is the final piece of the answer to the question of why there are two physical mechanisms for controlling light.

Shutter speed and aperture both allow you to control the brightness of your image, and as you've seen, shutter speed also allows you to control motion stopping.

Aperture, in addition to controlling brightness, gives you control of depth of field, and I will argue that depth of field control is something you'll think about a lot more often than motion stopping.

Unless you're a sports or wildlife shooter, motion control is not something you'll need to think about very often, but depth of field is something you'll consider every time you go shoot.  Because, for example, in a landscape shoot, you usually want to have very deep depth of field.

Portraits, as we've just seen, usually have shallow depth of field.

Product shots usually want deep depth of field.

In street shooting, your depth of field might vary a lot.

Like shutter speed, depth of field has its own corresponding set of numbers.

This may seem intimidating at first, but as with shutter speed, depth of field is very simple once you understand some fundamental concepts.

Apertures are measured in f-numbers, which have this odd progression, f2, f2.8, f4, f5.6, f8, f11, f16.

You should know that each one of these numbers represents the size of the circular opening that is the aperture in your lens.

You should also know that, from left to right, each one of these numbers represents an aperture that is half the size as the previous number.

In other words, each one of these apertures represents a one-stop difference in exposure.

The tricky bit here is that larger numbers correspond to a smaller opening.

So f16 is half as big as f11, or one stop smaller.

For example, if your camera chooses a 30th of a second as a shutter speed, a speed that might be too slow for handheld shooting, you know that you can increase the shutter speed by one stop to a 60th of a second.

But that's a change that will darken your exposure by one stop.

So to compensate for that, you can open your aperture by one stop to let in the same amount of light that your shutter speed change eliminated.

Those equal and opposite changes give you the same level of overall brightness in your final exposure, but with the advantage of a faster shutter speed in that case.

However, changing the size of your aperture does more than simply change the brightness of your exposure.

As shutter speed changes affect brightness and motion stopping power, aperture changes affect brightness and depth of field.

As your aperture gets smaller, depth of field increases.

For example, I'm going to look in this camera over here.

We're on a tighter shot here, and the background is about as sharp as what you've been seeing in this camera over here.

But right now, we're affecting a change in that other camera so that when I look back to it, depth of field is much more shallow than it was before.

And what I mean by that is the background back there is a little bit softer.

The change that we affected is that we opened up the aperture of this camera.

Before we had a very small aperture, which gave us deep depth of field.

Now we have a larger aperture, which is getting us a much more shallow depth of field.

Again, one is not necessarily better than the other in any sort of objective sense, but they do have very different feels.

Let's take a look at some stills side by side.

So in the left one, you can see I've got my smaller aperture, which is giving me deeper depth of field.

In the right hand image, I've got a wider aperture, which is giving me more shallow depth of field.

You can argue that the shallower depth of field kind of isolates foreground more by making the background less distracting.

Here's a landscape shot with very deep depth of field.

Shooting the scene with shallow depth of field doesn't really work in this case.

We want to see all of the details in the shot.

So going shallow doesn't work as well, in my opinion.

But again, depth of field is subjective, and very often your subject matter will drive your depth of field choices.

So now you have another factor to work with in your exposure balancing act.

Perhaps you're shooting in a dark room and your meter is reporting very slow shutter speeds.

You can, of course, increase the ISO, but you can only take that so far before your image becomes too noisy.

This will allow you to use faster shutter speeds, but it will also reduce the depth of field in your shot.

Depending on what you're shooting, that may or may not be a problem.

If you want to shoot in low light, have very deep depth of field, and freeze motion, that may not be possible.

In that situation, some cameras will do better than others because some cameras can have their ISOs pushed higher before they produce a lot of noise.

But still, there will be situations where, for reasons of practicality and physics, you simply cannot get the balance that you want.

Aperture then can be summed up as follows.

An aperture is a mechanical circular opening, usually contained in your camera's lens.

It can be made bigger and smaller, and as you make it smaller, the depth of field in your scene increases.

Smaller apertures are represented by larger numbers.

You just need to memorize all of that, it won't take long, and soon the particulars of aperture will be second nature.

However, these aren't the only things that you need to know to take control of depth of field.

Wider apertures make for shallower depth of field, but aperture is not the only thing that affects the depth of field in your image.

Sensor size, the distance to your subject, and the size of the objects in the background of your image all have a bearing on how soft the background will go.

Smaller sensors have inherently deeper depth of field than larger sensors.

This has nothing to do with sensor technology, it's just a fact of the physics of optics.

Smaller pieces of film also have inherently deeper depth of field than larger pieces of  Here's a portrait shot with two different sized sensors.

It's got a tiny smartphone camera sized sensor in it.

It has a fixed aperture, and it has a very particular focal length.

That is, it has a lens of a particular length.

Here's a portrait shot from the same position with a Canon 5D Mark IV.

It has a sensor that's the size of a 35mm piece of film.

That's dramatically larger than the sensor that's inside the iPhone.

I set it to the same aperture, and I used a lens of equivalent length.

In other words, pretty much everything is equal in these shots except for the sensor size.

And as you can see, the iPhone produces much deeper depth of field than the SLR does.

If you want the option to shoot with the shallowest depth of field possible, then you'll want to choose a camera with a bigger sensor.

In general, though, any SLR or mirrorless camera, and even some high-end point-and-shoots, will be able to produce a nice defocused background if you know how to properly use them.

Because of their tiny sensor, smartphone cameras will never be able to get that blurry background.

These days, some cell phones have a special portrait mode which fakes the look of shallow depth of field by digitally blurring the background.

Sometimes that works, sometimes it doesn't work so well.

As you get physically closer to something, depth of field decreases.