Experimenting with aperture settings

The aperture has a similar function to the pupil in the human eye. The aperture setting on a camera determines how much light is allowed through as the shutter opens and closes. Also known as depth of field, and indicated by the f-stop number on a camera settings, having control over the aperture has many uses, including close up photographs such as portraits or macro photography. To control the aperture, select the AV setting on your camera. This means you can manage the f-stop number and let the camera work out the rest of the settings.

A smaller aperture number (say f/4.5 for example) will allow more light in and reduce the depth of field. This means that objects towards the front of the photograph (such as a face) are in focus, while the background is blurred. This blurring effect behind the subject is known as bokeh (from the Japanese for ‘blur’ or ‘haze’).

To practise setting the depth of field I created an outdoors scene in which there was something happening close to the camera and there was also action further away. The first photograph has an aperture of f/4.5 so, as you can see, the depth of field is small and the background is blurred. The camera used a shutter speed of 1/60 second and an ISO of 125 for this photograph.

Next, I wanted to concentrate on the action both right in front of the camera, and further behind. To extend the focal range I set the aperture to f/27. As you can see, the action further back in the picture is now clearer and you can make out figures and a motorbike. The other settings for this photograph were shutter speed of 1/45 and ISO of 2500.