Getting blurry with depth of field
If you’re looking for a low tech way to create a beautifully blurry background, keep on reading. We’re looking at how the photographer’s position can impact a photograph. All too often photographers stay in one place while they take a series of photographs. If you do this, you’re missing out on so many opportunities to completely change a photo by moving yourself.
In this tutorial we’re looking at moving around to impact depth of field. This is such an easy low tech way to create a beautifully blurry background without spending a fortune on a really expensive lens.
What is depth of field?
We’ve written a detailed explanation of depth of field in this tutorial: Using depth of field for gorgeous photography composition
So I’ll just briefly explain depth of field and we can get onto discussing how to manipulate it by moving around. Like anything that involves depth, there is a shallow type and a deep type. You’ll also hear it referred to as narrow depth of field and wide depth of field, respectively.
Deep (wide) depth of field
You will see deep depth of field used mostly in landscape photography. This is because landscape photographers generally want front to back sharpness. In other words, they want both the foreground and the background to be as sharp and in focus as possible.
Shallow (narrow) depth of field
Portrait photographers in particular like to use a shallow depth of field, except for when photographing groups. This is because they want a “blurry background” behind the subject so that the subject stands out. This is also known as separating the subject from the background.
What affects depth of field?
There are four ways to manipulate depth of field:
- focal length
- camera sensor
Okay, let’s get back to the main subject of this post – altering the look and composition of an image by moving. We’re looking at using distance to control depth of field by moving. Distance between your subject and the background, as well as distance between you and your subject.
How does distance affect depth of field?
When considering distance, we’re talking about the distance between photographer and subject, as well as the distance between subject and background. The closer you are to your subject, the smaller the field is. As the distance is compressed, there will be more of an impact with small changes in distance. It’s a ratio thing.
Let’s look at 3 distances to put it in perspective. We’re looking at the distance between you (the photographer) and the subject in relation to where you are photographing.
Imagine you’re at one end of a football pitch and your subject is on the half way line. If you take at step forward on your end of the football pitch, it’s not going to make much of a difference.
Now imagine you’re at one end of your living room and your subject is in the middle. Unless you have some kind of insanely big home, there will be a massive difference in distance between you and your subject. If you took a step forward in your living room, proportionally that is a huge difference.
Now imagine you’re standing in an elevator with your back to the wall and your subject is in the middle. If you take a step forward, you’re going to be very up close and personal.
So, you can see how distance is relative. How do we translate that to being able to work out what the depth of field is? In other words, how can you know what the area of focus is around your subject in these three examples?Great gear does not make a great photo. It’s in the eye, the hands and the feet of the photographer.Click To Tweet
Working out the depth of field (area of focus)
The area of focus either side of your subject is a standard proportion of the distance between you and your subject. This is roughly 1/3 of the distance in front of your subject and 2/3 of the distance behind your subject.
Let’s go back to our 3 examples to illustrate. I’ll use yards as the unit of measurement in all 3 examples for consistency.
If your subject is on the half way line of the football pitch and you’re at the end, your subject is about 50 yards from you. So the area of focus is roughly 16.5 yards in front of your subject and 33 yards behind your subject.
Let’s say when your subject stands in the middle of your living room, and you have your back to the wall, they are 3 yards from you. The area of focus will then be 1 yard in front of your subject and 2 yards behind your subject.
In the middle of an elevator your subject will be 1 yard from you with your back to the wall. The area of focus is much smaller now, with just 1/3 of a yard in front of the subject and 2/3 of a yard behind the subject.
You can imagine how every centimetre of movement in the lift is going to make a difference when you have only 92 centimetres (1 yard) to play with.
If you’re used to using a zoom lens you might have got into a bad habit of not moving around enough during a shoot. If you “zoom with your feet” to get closer to the subject you will start having a greater impact on the depth of field of your photos.
By zooming in with a zoom lens we change the focal length of the lens and therefore magnify the image to get in closer. However, if we zoom in with our feet, the depth of field impact (a.k.a blurry background) is far greater.
This is an especially important point to remember if you are using a kit lens with your camera or a prime lens that doesn’t open wider than f5.6. The zoom lens that came with your camera is not as optically advanced as the more expensive zoom lenses. It therefore won’t achieve the same easy level of “beautiful blurry background” as the fancy lenses. This is why they are more expensive – there are some serious optics inside those lenses. They are far more technically advanced.
Before you feel the need to rush out and buy a better lens to take better photos…please stop right there. We absolutely do not advocate upgrading gear to improve photography. There are many ways to take a great photo…and they do not involve blowing your savings.
If you have a kit lens or a lens that doesn’t go wider than f4, your biggest ally is space. So you need to use it. Zoom with your feet. Change the distance by physically moving yourself closer to your subject, or further away from your subject, or move your subject further away from the background.
What happens when you zoom with your feet?
As we’re photographers, let’s talk in photos.
PS: for consistency, all these photos were shot at f4 with a shutter speed of 1/500 and ISO 200.
Here are two photos where our lovely model, Shelby, remained in the same place, but I moved. The focal length is 70mm in both photos.
In the first image the distance between Shelby and me is shorter, although she is still the same distance from the background. Proportionally, the background is therefore closer to Shelby than in the second photo. The underlined area = the area of focus
Background – – Subject – Photographer
The background is sharper in the second image, because it is still within the area of focus (underlined area = area of focus).
Background – – Subject – – – – Photographer
In these next two photos I remained in the same place and Shelby moved towards me. I also kept my focal length (62mm) the same as she approached.
Photographer – – – – Subject – – Background
She was shortening the distance between us and lengthening the distance between her and the background. As I was focused on her, the background became more out of focus the closer she got to me – the area of focus moved away from the background (underlined area = area in focus).
Photographer – – Subject – – – – Background
So, get moving. For no reason other than to create beautifully blurry backgrounds. Or not. Maybe you want front to back detail. Either way – the solution is in your feet, or your subject’s feet.
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If you have any questions about how to use distance to create images with a blurry background, let us know in the comments.
Also, we love good news, so if our photography tips on changing position to improve composition have helped you to understand how to control depth of field, share that too.