Selective Focus In Photography (…and how to use it well)

If you are used to taking photos with your phone, then you probably just have most of the image in focus most of the time.

But with cameras and lenses that give you more control, you can use selective focus to enhance the image and bring attention to the most important parts of it.

What Is Selective Focus In Photography?

Selective focus is a photography technique of focusing the camera on your subject while rendering the rest of the image out of focus. It helps to bring the attention of the viewer to the subject.

It is relatively easy to learn the basics and it is a technique that goes a long way towards making your images look more professional.

Separating The Subject From The Background

The main reason that you would use selective focus is to separate the subject from the background or other elements in the image.

Doing that brings attention to the subject and not everything else in the frame. This is useful for portraits but can also be used in many other types of photography when the important part of your image is a single object or person rather than the entire scene.

There are some things you need to know in order to blur the background in a photo (and do it effectively).

Let’s cover them now…

Using Shallow Depth Of Field For Selective Focus

The way to achieve that professional selective focus look in your images where the subject is in focus and the background falls off to a very aesthetically pleasing blur (often called “bokeh”) is by using something called shallow depth of field.

Depth of field is the range of distance from your camera that is in sharp focus. Depending on the lens and settings you are using, that range can be large or it can be small.

When you use your camera settings to create a small range of distance that is in sharp focus, photographers call that a shallow depth of field.

Choosing A Focal Point

When using selective focus, choosing your focal point is one of the most important steps towards creating a good image.

Selective Focus For Portraits

If you are shooting a portrait of a single person then it’s actually quite easy to choose your focal point.

Unless there’s a specific reason to do otherwise, you should be focused on the eyes of your subject for a portrait. In fact, if you are getting close to them, like a headshot, for example, then you should be focused on the eye that is closest to the camera.

Because we tend to focus on a person’s eyes when we talk to them in person, an image where a person’s eyes are in focus will appear “correct” to the human eye.

In fact, if you have an image where the eyes are in focus and the rest of the face is slightly blurred due to a very shallow depth of field, your brain will still register that image as being “in focus.”

On the other hand, if the eyes of a person are out of focus and everything else is in focus, the image just won’t look quite right.

If you are shooting more than one person, check out my article on shooting group photos with a 50mm lens for a more detailed discussion on dealing with depth of field for group photos.

Selective Focus For Landscapes

Here, things get a little more complicated as you’ll have some decisions to make.

First off, in general, the goal for landscape photos is to get the entire scene in focus, so you should have a very compelling reason to use selective focus for a landscape image.

Often, you’ll want to employ this technique when there is a small but compelling subject like a flower or a shell on the beach and you don’t want it to get lost in the larger landscape.

But, when using this approach, it’s always a good idea to shoot multiple photos both with and without using selective focus. You might not know which one you like better until you get it back home and look at them on your computer.

Aperture Setting Controls Depth Of Field

The primary way you can control depth of field is by changing the aperture setting on your camera.

There are two basic things you need to know about aperture to control depth of field.

This part confuses beginners so pay close attention…

1. A larger number (or f-stop) means a smaller aperture and a smaller f-stop number means a larger aperture.
   
2. A smaller aperture increases the depth of field and a larger aperture decreases (or shallows) the depth of field.

So that means if you want to have the most shallow depth of field possible for your lens, then you want the largest aperture (which means setting it to the lowest number f-stop).

Below is a table that shows you how changing the aperture can affect depth of field. You’ll see that the focal length and the distance to the subject stayed constant.

As you can see, changing the aperture has a drastic effect on how much of the image is in focus.

Let’s look at some real world examples to help understand how this works practically…

Here are two images I took on the same day, around the same time and within about 50 feet from each other.

In this first image, I used an aperture setting of f/3.5 and you can see that the background is blurred out and I have selectively focused on the flower.

You can still tell that there are trees and a cabin in the background but they are just blurred enough so as not to draw the attention of someone viewing the image. Because I am using a wide-angle 16mm lens, the depth of field isn’t as shallow as if I had used a longer focal length…but there’s more about that below.

In this second image, I used an aperture of f/10 and more of the trees in the background are in focus.

Having the background in focus here detracts attention from the yellow flower which is the clear subject of this image.

Fast Lenses For Selective Focus

Not all lenses will have a wide maximum aperture to let you achieve a shallow depth of field.

Your average kit lens that comes with entry level cameras has a maximum aperture somewhere between f/3.5 and f/5.6 and that often varies on a given lens depending on which focal length you are using.

If you want a lens that will allow you to get a very shallow depth of field, look for lenses with a wide maximum aperture. Photographers call those “fast lenses” because they can let in a lot of light.

Common maximum apertures that will give you a shallow depth of field can range from f/1.4 to f/2.8.

Prime lenses are often found in that f/1.4 to f/1.8 range and fast zoom lenses can be found with maximum apertures of f/2.8. Of course, a faster lens is going to be more expensive, especially those f/2.8 zoom lenses.

A great place for beginners to start learning to use selective focus is a 50mm f/1.8 prime lens. They are often the least expensive lenses in most systems.

Camera To Subject Distance

The closer you are to the subject, the easier it is to blur the background.

The reason for that is that as you get closer to a subject, your depth of field gets smaller.

For example, if you are using a 50mm lens set to f/5.6 and you are focusing on something 25′ away, your depth of field will be almost 35′. Take that even further to 50′ and the subject and everything behind it will be in focus (this is usually designated by the infinity symbol “∞”)

But if you move the subject closer, keep the settings the same and focus on them, your depth of field is only about 1 foot!

Using Extension Tubes

An inexpensive way to get a shallower depth of field without having to buy a new lens with a wide maximum aperture is to try using extension tubes.

These are often used for macro photography, but you can use them on a variety of lenses to effectively increase the focal length of your lens which will allow you to get closer to the subject with a more shallow depth of field.

Keep in mind that adding extension tubes will also decrease the amount of light getting to the sensor, so you will need more light (or a slower shutter speed) to compensate.

Getting Selective Focus Settings Right

One mistake beginners often make when they first start using a lens with a large maximum aperture is overusing that maximum aperture.

Shooting at f/1.8 or f/1.4 will give you a shallow depth of field but those settings also make it more difficult to get your subject in proper focus.

Take a look of this image below. Because it’s a shot of a single animal, you may be tempted to use a very larger aperture to blur the background.

However, if I shot this at f/1.8, much of the texture of the rhino’s skin would be blurred out and I think that is one of the most interesting parts of this image.

Here’s an example where the eyes of the dog are in perfect focus but the depth of field was too shallow to get the nose in focus. The result isn’t terrible because the eyes are sharp, but it would have been better if I got his full face in focus.

So remember, using selective focus, doesn’t always mean taking it to the extreme.

Best Focus Modes For Selective Focus

Most digital cameras have three main focus modes…single shot, continuous focus, and auto mode.

Choosing the right mode is very important when you are using a shallow depth of field because having the focus just slightly off can ruin an image.

If you are shooting a still subject, such as a landscape or a portrait of someone staying still, then single shot is usually going to be your best option. For DSLR cameras especially, single shot focus is going to be the most accurate.

Continuous focus is good for keeping focus on moving subjects. So if you are shooting sports or any kind of moving subject, continuous focus will give you the best chance at nailing the focus.

You shouldn’t use continuous focus with still subjects because sometimes, the continuous focus will keep trying to refocus even when the subject isn’t moving. This can cause a blurry frame every so often for a still subject.

Auto just lets the camera choose between single shot and continuous. This is helpful if you have a subject that is sometimes still and sometimes moving, like the rhino photo above.

Tips For Using Selective Focus

Keep these in mind when using shallow depth of field and you’ll get better results overall.

Don’t Ignore The Background

Just because you are blurring the background, doesn’t mean you can ignore it.

Whenever you take a photo, whether using selective focus or not, be sure to give at least a quick look at the background. Even if it is sufficiently blurred, certain things can be distracting such as bright areas or colors that stand out.

If there are distracting elements in the background they are going to draw attention away from your subject, effectively ruining the whole reason you used selective focus to begin with.

To fix this, you can simply adjust your positioning or the subject’s positioning, if possible, to get a better, less distracting, background.

Use A Tripod For Still Subjects

Another helpful tip for nailing your focus is to use a tripod when shooting still subjects.

If you have a very shallow depth of field, simply swaying back or forth a little with the camera in your hands can change the focus. So whenever possible, use a tripod to eliminate camera movement.

I even use a tripod for shooting portraits sometimes.

Changing Your Shooting Angle

If you can’t quite get the background blur you want for selective focus (or your lens doesn’t have a wide enough aperture) then there are other ways to reach your goal.

One way I like to ensure the viewer’s attention is on the subject is by changing the angle from which I am shooting.

Now this can be as simple as moving left or right to get a better background, but something a lot of people don’t think about is moving up or down.

Getting low for a shot can change the background dramatically, and often you can find a positioning where the only background is the sky. That ensures that there’s a huge distance between your subject and the background and the focus of the image will surely be on your subject.

But even the opposite is true. Getting high up can help declutter the background. You may not be able to blur the ground, but it is often less cluttered than a busy park or city street.

This approach works great when shooting portraits of kids. Try getting both high and low to help you control the background and get the focus on them.

Macro Photography

An extreme example of using the distance from the camera to the subject for selective focus is macro photography.

When you are shooting macro images, the depth of field is often going to be razor-thin. So getting focus for macro photography shots is very difficult.

But, because it can be tricky, it is a great way to practice shooting with selective focus. So find a macro subject that doesn’t move, grab your tripod and experiment.