What is Depth of Field? and how can you take advantage of this feature to put the emphasis on your main subject or create a sharper overall image? Photographer, Bryan Esler will give you some handy insights.
Images by Bryan Esler
As photographers, depth of field is something that's important to take into account with every image we produce. While it can create some cool creative effects like bokeh, it can also be used in professional ways to create a more appealing photograph.
Depth of field is often overlooked. This aperture controlled amount of focus is inherent in every lens made. It can be used to create blurred highlights known as “bokeh.” Professionally, depth of field is a great way to tell stories more effectively.
What is Depth of Field?
Simply put, depth of field is the "distance between the nearest and farthest objects in a scene that appears acceptably sharp in an image" (Wikipedia). Another way of stating this is that depth of field is the amount of acceptable sharpness in front and behind the actual point of focus. A large, or broad, depth of field (small opening large number i.e. f/16) has more of the image sharp and in-focus, while a small, or shallow, depth of field (large opening small number i.e. f/2.0) has less of the image sharp and in-focus.
When to Use a Shallow Depth of Field
Of course, you want your images to be in focus and sharp. It's also important to put an emphasis on your subject. Using shallow depth of field isolates your subject from what's behind. This technique is useful in things like environmental portraits, nature, sports and editorial photography.
Here, I wanted the coffee drink to be the main focus of my photograph. By going with a small f-stop number (f/2.5), I was able to blur everything else in the photograph.
Bokeh
Using a shallow depth of field can also create the effect known as bokeh, which occurs when you have a shallow depth of field and small blurry light sources behind your subject. Bokeh is Japanese for blur by the way.
You can see that by using a shallow depth of field (f/2.8) and having small light sources behind your subject, will create a bokeh effect with the out-of-focus lights that are present in the scene.
When to Use a Broad Depth of Field
When you're photographing a subject that has to be fully sharp, increase the depth of field by choosing a small aperture (big number) like f/16. This is particularly useful with landscape, architecture and product photography. On the other hand, it can mean that your background might compete with your primary subject for the viewer’s attention in the photograph.
By using a bigger f-stop number like f/22, you get more of your image in focus. This is quite useful for landscapes.
Controlling Depth of Field
Control depth of field by adjusting your aperture. By using a small f-stop number (and therefore opening up your lens), you create a shallow depth of field that blurs the background.
Alternatively, by using a large f-stop number (closing your lens), you create a broader depth of field, sharpening your image across the frame.
Aperture size controls depth of field. The larger the hole, (small number) the less depth of focus. As the aperture closes down to smaller holes, the depth of field and the aperture numbers increase.
The aperture dial isn't the only thing that will control your depth of field — the distance between your camera and subject also affects depth of field. The closer you move to your subject, the more blurry your background will appear. The further away you move, the larger your depth of field gets, and the sharper your image gets.
If you can't change your physical distance, change the focal length of your lens instead. The longer you go, the more shallow depth of field you'll obtain at a given aperture.
