The term Depth of field is common photography jargon. It refers to the part of a photo that is in acceptably sharp focus. The range of how much is in focus varies depending on your chosen settings and the camera and lens you use.
One of the first things photographers learn about depth of field is that the f stop setting controls it. This is correct but not complete information. There are other factors that govern the depth of field. These are the size of your camera’s sensor, the distance you are from your subject, and, apparently, the lens’s focal length. Managing these variables allows you to set a shallow or a large (or deep) depth of field.
Once you’ve learned to control the depth of field, you’ll be able to take more creative and interesting photographs. Getting the right amount of depth of field in a photo requires practice and experimentation. You need to know and understand what factors contribute to the depth of field and how to manage them. But first, let’s take more of a look at what depth of field is.
Table of Contents
- What is the Depth of Field?
- Which Factors Affect Depth of Field?
- The Effect of Lens Focal Length on Depth of Field
- How Subject Distance Affects Depth of Field?
- How Sensor Size Affects Depth of Field?
- Managing Depth of Field
- Why it’s Important to Control DoF?
- Tips for Managing DoF
What is the Depth of Field?
Depth of field refers to the distance, from closest to farthest, in a photo that appears to be in acceptably sharp or in focus. It denotes the extent of the photograph that is in focus.
When you focus your lens, everything at the same distance from your camera’s sensor will be precisely in focus. Anything closer or further away will not be so sharp. But whatever is ‘acceptably sharp’ is within the depth of field.
Certain types of photography typically work best when a lot of the image is in focus, such as:
- Group portraits,
There is no definitive list of subjects that require being photographed with a deep depth of field. Used well, depth of field is a creative aspect of photography and very subjective. Managing how much of your photograph is acceptable sharp helps to shape the mood of your image. There is no right or wrong way to do this. When you know how to, you can make better creative decisions based on the style of photos you want to take.
Let’s say you are looking at a landscape image that has everything in focus. This is an example of a deep depth of field. Landscape photographers often prefer to have as much of their pictures in focus as possible.
In this street portrait, the subject’s face, and more specifically her eyes, are in focus. Most of the foreground and the background are out of focus. This is an example of a shallow depth of field.
Which Factors Affect Depth of Field?
Factors that affect the depth of field include not only the aperture value. Camera sensor size, the focal length of the lens, and the distance from the subject to the lens also affect depth of field. The f stop is the first, and sometimes the only, contributing factor to the depth of field many photographers learn about.
Controlling the F Stop to Adjust Depth of Field
The F Stop, or F-Number, denotes the lens aperture setting. This is the size of the opening the diaphragm in your lens is set to. Every lens has this adjustable opening. It’s part of the exposure triangle and is used to help regulate light entering the camera. It also affects the depth of field.
The narrower the opening, the higher the f stop, the deeper the depth of field. Less light will also be able to enter the camera. The wider the opening of the diaphragm, the lower the f stop, the shallower the depth of field. More light will also be able to enter the camera.
In this article, we are looking at a depth of field, so I won’t explain how aperture settings affect exposure. To learn more about this, please take a look at these articles.
When you want to take a photo with a deep depth of field, you can choose a small lens aperture. That’s a high f-number. The smaller the aperture diameter, the deeper the depth of field.
Taking photos with a very shallow depth of field requires a large aperture. That’s a low f-number. The wider the aperture diameter, the less of your photo will be in focus.
Being able to manage the f stop setting well, you can better control how much of your photo is in acceptably sharp focus. However, you also need to work with the other factors that contribute to the depth of field as it’s not all about the f stop you choose.
The Effect of Lens Focal Length on Depth of Field
The focal length of the lens also is a contributor to the appearance of depth of field. A longer focal length lens will produce a shallower-looking depth of field compared to a wider lens. That is one reason landscape photographers prefer using lenses with short focal lengths.
Consider taking a photo with a 300mm lens and a 50mm lens on cameras with the same size sensors. Both lenses are photographing the same subject. They both are focused on the same distance and have the same f-number setting. The photos taken with the 300mm lens have a shallow depth of field than a photo taken with a 50mm lens.
The composition will also be a lot different. This is because the longer focal length lens crops in tighter when at the same focus distance as the 50mm lens. Elements at different distances from the camera also appear closer together with the longer lens. Telephoto lenses have the characteristic of compressing depth in compositions.
This makes it more challenging to achieve a deep depth of field when using lenses with long focal lengths. As focal length increases, the depth of field looks shallower. This is why you don’t often see close-up photos of dangerous animals with a deep depth of field. The photographer has to use a longer lens to keep their distance. So they get a shallow DoF.
Some technical-oriented photographers argue that the depth of field is the same with longer focal length lenses as it is with wider lenses. I prefer to explain photography more pragmatically. Practically, what we see in a photo is what matters. Using a longer focal length lens, the background looks more blurred than when using a wider lens.
How Subject Distance Affects Depth of Field?
The closer what you are focused on is to the camera, the shallower depth of field your photo has. The further away you are focused, the deeper depth of field your photo has. This relationship with subject distance is true for any camera and lens combination.
In macro photos, only a small part of the main subject might be sharp. This is because the camera to subject distance is very short. So, even when you set your f stop to the highest number when you are focused very close to your subject, you may only have a very shallow depth of field.
When you want to isolate a building or tree in a landscape, it can be challenging to create a shallow depth of field. You need to back up from your large subject so you can capture all of it. The more you back away and increase the focal point distance, the more your image will look acceptably sharp.
Even with a standard prime lens, like a 50mm set at f/1.4, you may not achieve a shallow depth of field. When you are far enough away from your subject to include it all in your frame, you will have a deeper DOF. Using a wider focal length lens allows you to get closer and include the whole subject. But you’ll still be challenged to create a shallow depth of field because of the wider focal length lens.
If space allows, backing away from your large subject and using a longer focal length lens is an option. If there are obstructions, then getting further back may not be practical.
How Sensor Size Affects Depth of Field?
Sensor size has a major influence on the depth of field. The larger the sensor in your camera, the shallower depth of field it captures. This has nothing to do with the number of megapixels which is sometimes confused with sensor size. It’s the physical dimensions of the sensor that are relevant.
With any lens set to the same aperture, the photos taken on a larger sensor have a shallower depth of field than those taken on a smaller sensor.
Let’s say you are using two cameras: one a full-frame camera and the other an APS-C DSLR. You are trying to compose the same photo with the same focal length set to the same aperture. With the APS-C camera, you will have to step back away to capture the same composition. This happens because the smaller sensor effectively only sees a small section of the composition. When you step back, the depth of field increases.
If you’d like to know the technicalities for this, please read my longer article on Depth of Field where I dig into more details on this whole subject.
Managing Depth of Field
Juggling aperture size, camera-subject distance, and lens focal length might seem a bit much when all you want to do is take a few photos. But it is important to manage your camera technique for mastering depth of field. Knowing the style of photo you want certainly helps figure out the desired depth you produce in any picture. A photo with a deeper DOF looks remarkably different than a photo of the same subject with a shallower DOF.
Taking time to learn and practice with the basic equipment settings, you’ll soon be able to create great photos. Each one having as much of the composition as sharp as you want it to be. You’ll be able to do this with any given focal length lens and minimize or maximize depth as you think best suits each photo you take. Deciding the style of images you want to take helps determine how much depth of field to incorporate into your photos.
Is it important for the closest and farthest objects to be in sharp focus? Will your main subject stand out enough if you use a small aperture? Will decreasing the shutter speed help you maximize depth of field?
How Much Light is There?
One of the first considerations has to be how much light do you have to work with. Aperture size not only influences the depth of field, but it is also part of your exposure calculation. This means the aperture size you set makes a difference to how much light hits the image sensor, not only to the depth of field.
In low-light situations, you may want to take photos where the entire image is sharp. Managing your camera settings in low light is often more challenging. To obtain a greater DOF you’ll need to work with small apertures. This will mean balancing your exposure with a slow shutter speed and/or a higher ISO setting.
On a bright sunny day or other situation when there’s a lot of ambient light, it can be challenging to create photos with a very shallow depth of field. You’ll need to work with your aperture setting to ensure good exposure. This can mean having to use a small aperture when you want to choose a large aperture. In these situations, decreasing camera subject distance or using a telephoto lens can help.
So you need to be mindful of how aperture affects not only depth of field but also exposure. This is why so many photographers prefer working in aperture priority. It helps them manage their camera settings more easily. The photographer chooses the f stop in aperture priority mode, and the camera manages the shutter speed. Doing this supposedly means you don’t need to think about your exposure as the camera manages this for you.
I do not find aperture priority particularly satisfactory. This is because the camera does not know what you are photographing. It also never knows what your intent for your photos is. Manual mode provides you with more flexibility in both exposure settings and image sharpness. It doesn’t take long to learn to use manual mode when you set your mind to it. When you practice and learn a little frequently, you can master your basic equipment settings in no time.
What Lens is Best for this Subject?
Sometimes you have many options for what focal length lens you can use for a photo. Other times you will not. Photographing wildlife and sports matches generally requires the use of a long focal length lens. You’re hardly likely to capture a photo of an aggressive grizzly bear with a wide-angle lens and live to tell the tale of it. At times wide-angle lenses are not appropriate to use, so you are challenged when you want to take photos with greater depth.
When your options are more open, you can choose which lens to use based on how you want to compose your subject. You can also pick a lens with a wider f stop to help you get a very shallow depth of field. If you are photographing products or portraits, you have more choices about which lens to use.
Think about what you can frame with a lens at any given focus distance and how this affects the depth of field. Sometimes it might be better to move back and open your aperture up. This can give you the same depth as having a closer focus point and using a wider aperture diameter. You’ll need to keep in mind the crop factor of your image sensor when choosing which focal length lens to use.
With macro photography, you have to get in close, so you need to use a lens that can manage a short focus distance. Macro photography requires special lenses for this or other basic equipment to allow you to obtain a short focus point.
Why it’s Important to Control DoF?
You can isolate your subject using a very shallow depth of field. You can create a deep depth of field when it’s important to have the closest and the furthest objects sharp. Controlling the depth of field in your photographs can help convey meaning and produce the desired atmosphere.
Portraits with shallow depth of field help draw attention to your subject. A tree, building, vehicle, or any other subject can be made the center of any composition when you isolate it using a shallow DOF.
Any time you want sharp images with a maximum depth of field, you can control this. Sometimes it means landscape photography with a wide-angle lens and a small aperture. It often involves choosing the most effective focal length and setting a slow shutter speed so you can use a narrow aperture.
Your intent is what makes the difference. Knowing how you want your photo to turn out guides your choices for controlling the depth of field. But it’s not only a matter of choosing between a very shallow depth of field or a deep depth of field. Being in control of how much of your image is sharp allows you to create more interesting compositions.
At times you’ll want some of what’s behind your subject to be blurred, but not so blurred that it becomes unrecognizable. Creating bokeh is not always what’s most important. Maybe you’re taking an environmental portrait. Your subject is sharp and so are whatever elements are on the same focal point or plane. Some of the backgrounds may be relevant too, but it might be distracting if it’s all in sharp focus. In this situation, finding the sweet spot in the focal range for how much depth of field can truly enhance a photo.
Too much depth of field can distract attention from the main subject. Too little depth of field can eliminate too much relevant information. Finding a balance where what’s in the background is visible and recognizable but not invasive is the superb depth of field management.
Tips for Managing DoF
Know What Your Want
Having a clear idea in mind for how you want your photos to turn out is one key to becoming a successful photographer. Part of this is knowing how much of each photo you take to be sharp. Leaving this to chance does not help you produce more creative photos. Instead, it will lead you in the opposite direction, and you’ll end up with a higher percentage of images you throw out.
Manage Your Focal Length
Purposefully choose which focal length lens you will use partly based on how much depth of field you want. Think about how far away your focus point needs to be with any given focal length lens. Let this factor into your calculations. You may also want to look at the hyperfocal distance when you want a deep depth of field.
Choose the Most Effective F Stop
Set the f stop to achieve the style and amount of blur you want. This will depend on the effective focal length of the lens you’re using and the crop factor of your image sensor. You will get used to this when you practice often. You can build a real sense of knowing how much of your photos will be in focus with any given lens and focus point when you practice enough.
Close Means More Blur
When you want a shallower depth of field, get in closer. Reduce the distance between you and your subject, and you’ll see less of the background in focus. This is true whether you’re using a wide-angle lens, a medium lens, or a telephoto lens.
Use A Depth of Field Calculator
A depth of field calculator is a handy tool that shows you how much of an image will be in focus when combining the various contributing factors. This can help understand the depth of field.
Learning how to make the most of your camera and lenses by controlling the depth of field is a key aspect of taking your photography to the next level. It’s always best to take your camera out and experiment with different techniques to find what works best for you.
We found a couple of videos on depth-of-field you’ll find are very informative. The first is from Dylan Bennett, where he explains the depth of field, how it works, and how to control it. The second video on the depth of field is from Mark Wallace for Adorama Photography TV.