Depth of Field Explained

By Geoff Harris

Depth of Field Explained, Understanding Deepth of Field, DOF, Aperture,

Understanding Depth of Field

Learning how to understand and control depth of field in your photographs is one of the best ways to take your photography to a new level. And it’s not difficult! So what is it, and how do we use it?

The term depth of field is defined by Wikipedia as “the distance between the nearest and farthest objects in a scene that appear acceptably sharp in an image.” So in a photograph with a large depth of field, most of the objects in both foreground and background will appear sharp. In a photo with a shallow depth of field, the object that the photographer focuses on will appear sharp, while areas in front of or behind it may appear soft and out of focus.

Depth of Field Explained, Understanding Deepth of Field, DOF, Aperture,

The amount of depth of field is controlled by setting the aperture in your camera’s lens (The hole size). The aperture settings are known as f stops, and are represented by a range of numbers from around f/2.8 to around f/32. The exact range will vary from one lens to another.

The lower numbers (f/2.8 etc.) will give you a wide aperture (a large hole), while the higher numbers give you a small aperture.

And a wide aperture will give you a shallow depth of field, while a small aperture gives you a large depth of field.

So the rule of thumb is, the higher the f stop number, the larger the depth of field!

Depth of Field Explained, Understanding Deepth of Field, DOF, Aperture,

The exact depth of field in any situation will also depend on the distance between yourself and the subject that you are photographing. And this is also related to another factor – the type of lens that you use.

If you photograph the same subject from the same place with different lenses, a telephoto lens will give you a shallower depth of field than a wide angle lens. For instance, if you focus on a tree with a 300mm lens, you will have a much shallower depth of field than you would if you photographed the same tree from the same position with a 28mm lens, at the same f/stop setting.

Depth of Field Explained, Understanding Deepth of Field, DOF, Aperture,

However, if you were to move closer to the tree and photograph it with the 28mm lens in such a way that the size of the tree in the resulting image was the same as in the image taken with the 300mm lens, then at the same aperture setting, the depth of field given by each lens would be the same as well.

If this is getting a little too complicated, then just go back to the golden rule - the higher the f stop number, the larger the depth of field!

Depth of Field Explained, Understanding Deepth of Field, DOF, Aperture,

Then in any given situation, you can evaluate the scene in front of you, and decide whether you would like front to back sharpness or not. You might choose to use a shallow depth of field in order to emphasise just part of the scene by throwing other areas out of focus. Typical examples of this might be isolating a flower and throwing its distracting background out of focus, or taking a portrait of a person against a background which doesn’t add anything to the image when it is sharp.

In other situations you may want front to back sharpness in your photograph, perhaps in landscape or architectural photography.

But there are no rules about this, and the decision about depth of field is one of the creative choices open to the photographer – and one which will significantly affect the resulting photograph.

25-01-2013 09-36-52

Geoff Harris

I am a journalist and photographer and currently work as the Deputy Editor of Amateur Photographer (AP) - the oldest weekly photographic magazine in the world. Before that I served as the editor of Digital Camera, Britain's best-selling photography magazine, for five years. During my time as editor it became the UK's top selling photo monthly and won Print Publication of the Year at the 2013 British Media Awards. As well as being lucky enough to get paid to write about photography, I've been fortunate to interview some of the greatest photographers in the world, including Elliott Erwitt, Don McCullin, Martin Parr, Terry O'Neill and Steve McCurry. This has been a wonderful learning experience and very influential on my photography. Beyond writing, I am a professional portrait, travel and documentary photographer, and reached the finals of the 2016 Pink Lady Food Photographer of the Year competition. I am a Licentiate of the Royal Photographic Society and hope to take my Associateship whenever I can find the time. In addition I write about well being/personal development and antiques collecting for a range of other titles, including BlueWings, the in-flight magazine of Finn Air.

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