As we saw in the Exposure section our eyes focus and adjust to brightness very quickly when we look at something. In photography, things are very similar.

Most modern cameras have automatic lenses so we don’t have to worry about setting the focus. Nevertheless, it’s worth knowing how lenses work so that we can set up a manual camera correctly if we need to and for one other very important reason - DEPTH OF FIELD.

Knowing about Depth of Field and how to use it can make the difference between a so so snapshot and an outstanding photograph.

Compare these two images -

Notice how the iris flower on the left doesn’t stand out against the background, like the one on the right.

These photographs were taken using the same camera in the same position, within a few seconds of one another. The foreground and background of the one on the right is much more blurred, and therefore less distracting, than the one on the left.

Composition, lighting and exposure are the same for both shots but by knowing how to control Depth of Field, we can vary the appearance of the final image.

If your camera allows you to adjust the aperture, try photographing the same scene using the largest aperture (low number such as f4.0) and the smallest aperture (high number such as f22.0). If your camera does not allow you to adjust the aperture in this way, it might have settings for subject type; such as "Close-up" and "Landscape" - using these will give you similar results.

How is it that the same lens on the same camera can produce such different results?

Now we can see the effect of using a large aperture setting on the camera.

As with composition, lighting and exposure, it’s best to try these things out - so have a go.

It won’t be long before you will be taking better photographs now you know how the professionals do it.