Photo Tip of the Week: How to Master Depth of Field

Robert Keeley explains how you can use depth of field to add extra impact to your images.


Most dedicated amateur shooters have some understanding of depth of field, but many don’t really appreciate how they can use it more creatively in their images. Depth of field refers to how much of the image appears in focus in front of, and behind, the key point of focus in your image. In an image with a shallow depth of field some elements will appear in sharp focus while the background and foreground of the image fall away into a soft blur.

In an image with a broad depth of field the image will appear quite sharp from front to back. As photographers we can use depth of field creatively to affect the way people perceive and respond to our photos.

Using a short depth of field we can make a key part of an image pin sharp (say, the eyes in a portrait), while reducing the appearance of potentially distracting elements (for example, a cluttered background). Conversely, using a broad depth of field allows us to show the complete range of detail in a scene, particularly useful in subjects such as landscapes.



By using maximum depth of field the photographer was able to add the foreground interest of the red flowers, but still maintain sharpeness through to the far distance.

There are four main factors that affect depth of field – aperture, camera-to-subject distance, lens focal length and the camera’s sensor size. For any particular f/ stop, if you move your camera closer to the subject or use a longer focal length you’ll decrease depth of field. Conversely you can increase depth of field by moving further away from your subject or shooting with a wider angle lens. At a constant distance, using a wider aperture will decrease depth of field, while setting a narrower aperture will increase it.

Aperture: Aperture refers to the adjustable opening or iris inside the lens. Generally speaking a small aperture (for example, f/22), creates a large depth of field, while a large aperture (eg, f/2.8) creates a shallower depth of field.


A small aperture is the key control when you want to maxmise the depth of field in any image.

Lens focal length: In simple terms, it’s much easier to create shallow depth of field effects with a big zoom or telephoto lens than it is with a wide-angle lens which tends to render everything in relatively sharp detail.

Sensor size: Discussion of sensor size as it relates to depth of field is a little more complicated than it first appears. Basically, for two
different format sizes, if all other factors are equal (same distance from the subject, same apertures, lenses offering the same angle of view, and you’re viewing images at the same sizes) depth of field is inversely proportional to the format size. That is, a smaller sensor will offer more depth of field, while a larger one will present less depth of field. But this is an approximation that applies with some riders.

Camera-to-subject distance: The closer a lens is to the subject, the less depth of field will be available.


Photographing flowers is a key example where the close proximity of the lens to the subject will create a shallow depth of field.

If depth of field is something you particularly want to control in a photo try setting your exposure mode to Aperture Priority. In this mode, the photographer manually sets the aperture while the camera automatically chooses the required shutter speed to create a balanced exposure. You’ll be determining how much depth of field is created in your scene. So it’s relatively easy to start using depth of field as a creative element in your picture. But how should you use it? Your decision on what depth of field to select should be based on your creative objectives.

Great Depth of Field

Subjects which effectively recede into the distance for a long way can benefit from setting up extended depth of field. Lines of trees along a road, fences, or even rows of people can gain strength from shooting them with great depth of field. That means from close subjects to subjects further away, we can see a lot of detail.


Certain subjects will lend themselves to use of extended depth of field. But the alternative can often also be highly effective.

But conversely, if you want to emphasise just one part of such a scene, shallow depth of field will allow you to do this effectively. Many landscape images are shot using smaller apertures (like f/11, f/16 or even f/22), and because this frequently results in slower shutter speeds for a correct exposure, tripods are used to hold the camera very steady. Great depth of field works with landscape scenes because we can see detail from the foreground to the background and our eye is drawn through the scene.

Any scene where you wish to hold the viewers attention from the foreground to the far distance will need great depth of field. You should also be aware that the smallest aperture settings (used in an effort to create maximum depth of field) can result in diffraction problems (deflected rays of light), which can tend to defocus your image. To avoid this problem some landscape shooters recommend shooting anywhere between f/11 and f/13.

Shallow Depth of Field

Opposed to that, shallow depth of field works where you need to isolate a subject. Portrait photographers tend to use shallow depth of field to minimise distractions behind their subject. But it can also work on any subject where you want to focus the viewer’s attention on one specific element.



Even when subjects extend into the distance, a shallow depth of field should be considered for a different type of perspective on a scene.

Flower photographers can use shallow depth of field, but macro photographers are working within the limitations of shallow depth of field to begin with. These photographers know that shooting macro images actually requires them to maximise their depth of field because they’re shooting extremely close to their subject. The physical proximity of the subject to the lens usually means they don’t have much depth of field anyway.

These days focus-stacking techniques (where photographers make a series of images of an object which are sharp at varying focal lengths, then merge them using software to produce a very sharp overall scene) are becoming more common, though they require a degree of skill (and patience) to implement. There are now a range of software programs which allow you to create this type of image.

Controlling Backgrounds

For the less technically inclined, shallow depth of field can still be used effectively. It can be particularly useful if you’re shooting any subject with a distracting background. While the first option is usually to move either your subject or yourself to change the offending background, if this isn’t possible you can opt to use a shallow depth of field.


In this scene the photographer wanted to concentrate interest on the foreground flowers, so a shallow depth of field was used to keep our focus on the foreground. Shallow depth of field can be used if you want to mimimise any interest in a background.

It’s worth noting that this works better if you can at least put some distance between the background and your subject. If you want a shallow depth of field it also helps if you can shoot using a telephoto focal length. Because of the optics involved, telephoto focal lengths produce a shallower depth of field. But take note that tricky backgrounds can still create distractions, even if they’re blurred out. Bright spots behind a darker subject will be distracting, even if they’re blurred, so it’s best to change your position, or adjust these spots digitally.

Hyperfocal Distance

Hyperfocal distance is a related subject to depth of field, and it can be used (often by specialist landscape shooters) to increase depth of field, but it’s a subject for another column. If you’re a keen landscape shooter, check out its definition on the web or in photo books.