For maximum front-to-back sharpness in a landscape or cityscape, use short focal lengths and apertures of around f/16 or smaller, and focus about a third of the way into the scene. To keep the camera steady during the longer exposure, use a tripod or increase the ISO instead.
Whether you're shooting people or animal portraits, the most successful shots are frequently those where the background is beyond the depth of field and consequently blurred. Longer focal lengths and wide aperture settings are a good choice here, although focusing needs to be bang-on.
Depth of field decreases the closer you focus, so when it comes to photographing miniature subjects the choice of aperture becomes crucial. Even the smallest aperture available on a lens may only give a depth of field measured in millimetres when the lens is used at its closest focusing distance.
How to choose the right aperture
Set the camera to Aperture Priority or, if time allows, Manual mode. These two exposure modes give you full control over the choice of aperture, enabling you to change from a wide aperture to a small one in seconds.
We've used the near extremes of this lens's aperture range to illustrate the impact that aperture has on depth of field. In reality, the change as you move through the range isn't so abrupt.