As we’ve previously discussed, for most of our macro/close-up photos we will need to position
the lens very close to the subject. The problem is that when the lens is that close, it makes our
depth of field very shallow.
In other words... It becomes virtually impossible to keep our subject in sharp focus from front to
back.
The closer your lens is to the subject, the shallower your depth of field but to fill the frame we
don’t have a whole lot of control over the lens’ distance from the subject. It’s got to be close! So,
we are forced to control the DOF in other ways, primarily with our aperture (f-stop) settings.
The smaller the aperture, the greater the depth of field.
An aperture (f-stop) is nothing but a hole. It is an opening in the lens that lets light go through
the lens and onto our photo sensor. We can control and adjust our depth of field by the size of the
opening (aperture) that we use. As mentioned, a smaller hole will give us a greater depth of field
and a larger opening will give us a more shallow depth of field.
This is an important concept to understand because depth of field is a major compositional
element in any photograph we take - whether it is a macro shot of an insect, or our kids playing
in the park - and it is important that you understand how to work with it.
We can – and often will – use a shallow depth of field to make our background blurry and force
attention onto our subject. (A larger aperture.)