Now here's a thing...

So in the second of my photography tips, I want to talk about depth of field.

The log is in focus, but the stacks of logs and trees in the background are out of focus.

Depth of field can be described as which parts of an image are in or out of focus.  So if you look at the image of the log above, you can see that the log is in sharp focus, but everything behind it is out of focus.  This effect is sometimes called 'bokeh' (boh-ke), which comes from the Japanese word meaning 'blur'.

So how do we achieve this?  Well, it's all down to the aperture one uses.  The aperture controls how much light you let into the camera.  A wide aperture (eg: f2.8), lets in a lot of light, and gives a shallow depth of field, as one can see in the above picture.  A narrow aperture (eg: f16) lets in a limited amount of light but gives a very large depth of field, which means most of the image will be in focus, like the image below of Blackrock Castle .

Blackrock Castle - everything from the castle to the lights and tanks behind are in focus.

There are additional caveats to what I've just said.  When focusing on a subject, depth of field is usually about one third in front and two thirds behind your focal point, but as your focal length increases it becomes more equal. 

Additionally, the depth of field is determined by the distance you are away from your subject.

The focus point is the corner of the cupboard and the focus drops off dramatically the deeper we go into the picture.

For the picture of the cupboard, I was very close and I focused on the corner and used f2.8, which gave a shallow depth of field.  If I had been on the other side of the room and used f2.8, the whole of the cupboard would have been in focus.

So to sum up:

Increase depth of field

  • Narrow your aperture (larger f-number)
  • Move farther from the subject
  • Shorten focal length

Decrease depth of field

  • Widen your aperture (smaller f-number)
  • Move closer to the subject
  • Lengthen your focal length

I hope that helps you understand depth of field.  Of course, depth of field is something I teach my students during the lessons I give.  To find out more about tuition, why not give me a call on: 086 738 8863, or drop me an email: