Depth of field

When would you use shallow depth of field?

A really good example of when it would be appropriate to use a shallow depth of field would be when taking photographs of people. In the example below, I have used a shallow depth of field for creative effect. I have focused on my hand and lens but blurred the background. I wanted to include the background so that the viewer can see what is going on in the image. But I wanted a shallow depth-of-field so that the background is not distracting and point of focus is in the centre.

self portrait

self portrait

When would you use a large depth-of-field?

A prime example of when you would want to consider using a large depth-of-field, would be when photographing landscapes. Generally (but not always) you want front to back focus in landscaped photography. In the example below, I have used a large depth-of-field so that you can see foreground detail in the grass and on the path as well as detail in the large hill of Higger Tor in the background.

The path to Higger Tor BY Jonathan Dudley

The path to Higger Tor BY Jonathan Dudley

How to control the depth-of-field on your camera? Depth-of-field can be controlled by making changes to the Aperture on your camera. Aperture is measured in something called F-Stops. Full F-Stops are as so: f/1, f/1.4, f/2, f/2.8, f/4, f/5.6, f/8, f/11, f/16, f/22, f/32. Aperture is a measurement of how much light enters the camera and can be compared to the pupil of an eye. So for example when there is low light in a room, pupils tend to be large so that more light can be passed to the back of your eye, and vice-versa for when it’s bright. A full f-stop such as f/2.8 allows twice the amount of light into your camera than compared to f/4. F/2.8 also allows half the amount of light into your camera than compared to f/2. So the smaller the number, the larger the aperture which doesn’t quite sound right but you can read more on aperture from the following linkAperture of f/4

Aperture of f/16

Aperture of f/16

Camera and lens limitations

Compact cameras

If you own a SLR camera, you will without a doubt have the ability to control aperture. But if you use a compact camera you will probably find that the function to change this is not available. Compact cameras are designed to make photography easy to use and so everything is pretty much automatic. However don’t be too annoyed by this, as camera manufacturers always allow you to change the scenery mode. For example you are likely to see modes for portraits and for landscapes.

  • You will find that using the portraiture scene mode will force the camera to use the largest possible aperture that it thinks is right for the scene. So this should produce a shallow depth of field when focusing on a person.
  • When using landscape scene mode, the camera will use a small aperture which will allow for a large depth-of-field.

Lens limitations

  • All camera lenses will display on them their largest aperture. On zoom lenses there are sometimes 2 apertures written on them such as f:2.8-f:5.6. What this means is if you zoom out fully you will be able to achieve f:2.8. But when you zoom in to the maximum, you will only achieve f:5.6.
  • On wide SLR lenses such as a lens which has the zoom value of 10-22mm. You will find achieving a shallow depth-of-field is quite tricky simple due to the way the glass is designed.
  • Macro lenses suffer quite badly from shallow depth-of-field when you don’t wish to produce shallow depth-of-field. This is again due to the limitations of how the lens is designed. So if you was photographing a flower really closeup, achieving front to back focus will be almost impossible. A lot of people use something called focus stacking which is where you take multiple photos focusing on different points of the macro shot. Then using photoshop to combine them all to create a large depth-of-field.
  • If you are photographing something where you wish to have a large depth-of-field with front to back focus. As the aperture needs to be small, it will let less light into your camera. The issue with this would be the possibility of camera blur. As counteract your camera allowing a small amount of light into your camera, is the camera will need to keep the shutter open for longer. A slow shutter speed means, you will probably have a blurred image at the end of it. In this case use a tripod to steady your camera.
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