Focus as a compositional tool

The human eye is flexible & adaptive. When we look we see things as though everything is in sharp focus.

A camera lens freezes focus – so we notice when viewing the results the resulting photo that parts of the image are no in sharp focus and those that are.

Photographers use focus as a compositional tool in two ways

• To direct attention (as the photograph below demonstrates)
• To obscure distractions

By controlling focus, you can control a viewer’s attention, as sharp focus helps to build & support visual relationships.

So how do you achieve selective focus?

Selective focus is otherwise known as depth of field (the angle of distances in front of a lens that are rendered in sharp focus).

Photographically speaking there are three ways to control depth of field

• Lens aperture. The smaller the aperture (the larger the f number), the more extensive the depth of field. 
• Lens focal length – although an aperture value produces the same exposure on any lens, depth of field will be shallower on a longer lens.
• Focusing distance – most lenses have on their barrels numbers that indicate how far away the lens is focused, as well as depth of field indicator lines that show the range of distances in sharp focus. 

October 13th, 2006