Photography Tips: Depth of field

In this photography tip, we shall look in more detail at Depth of field; what it means, how to control it and how to use it to your advantage.

Depth of field refers to the amount of the photograph which is in focus. It is determined by

• the focal length of the lens - longer lenses have shallower depths of field
• the exposure - larger exposures have shallower depths of field
• the distance to the subject - closer mean shallower

Depth of field is one of the key creative tools the photographer has at their disposal. Landscape photographers tend to use wide angle lenses and tiny apertures to ensure that everything in a scene is in focus. Portrait photographers do the opposite; they try to make the depth of field just deep enough to cover the subject and nothing else. That way the viewers eye is drawn to the subject.

In boudoir photography, it can serve an additional purpose - allowing you to shoot provocative poses without being pornographic.

This image by fabulous photographer Perry Gallagher (reproduced with his permission) illustrates the technique perfectly. f1.4, 1/80th second at ISO200.

When shooting with a very shallow depth of field be careful to make sure you don't go too far. Here are a few examples to use as a rough guide:

Note that at 100mm and above the depth of field is less than an inch when you are 4' from the subject - which means that if you focus on the eyes, the end of her nose may be blurred! In which case you need to move back or close the lens down a bit.