How to change Depth of Field

Depth of Field, originally uploaded by Ian Champ Photography.

Here's a series of photos that show the variation in depth of field by taking the same shot several times but changing the aperture for each shot.

At f 32 the iris hole is tiny and less light gets in. This gives you plenty of depth of field.

As the iris hole gets bigger (that is, the f number gets smaller) more light gets in - AND you get much less depth of field.

In this series of shots the "brightness" of the shots is kept more or less the same by speeding up the shutter speed as the hole in the iris gets bigger (bigger hole for the light to get in, but open for less time).