Many photographers are aware of the one-third/two-thirds foreground/background rule of thumb when taking pictures. However, this rule is not valid when the subject being photographed is very close to the lens. In the case of macro photography, this distance can sometimes be just mere centimeters in front of the lens! In macro photography, the near field (foreground) and far field (background) distances are in the order of half and half. That is to say, the two distances are approximately equal.

Now, some people may ask, “Why all this fuss about the depth of field, near field, far field terms when all I want is to simply take a picture close up!” The set of images shown above give the best explanation as to how critical the effect of controlling the depth of field can be to the final image. Note the gradual focused effect in both the background and foreground as the aperture is stopped-down from f/5 to f/64, and all this was done without re-adjusting the focusing ring!

Suffice to say, there are no hard and fast rules as to what apertures must be used for specific situations. It is more the case of knowing how the aperture will affect the final image and deciding on what sort of effects, including sharpness, best suit the composition (this is of course dictated by YOU, the photographer!)..