How to Define your Subject using Depth of Field

What is Depth of Field?

DOF is the distance between the nearest and farthest objects in a photograph that appear reasonably sharp. Think of this area as the focal plane as well. Lenses can precisely focus on a given point. However, anything closer or further away from that point begins to leave the focal plane. This is how you get the nice blurry backgrounds you see in some photographs or the tack sharpness in others.

  • The smaller the opening (higher the f-stop number) the greater depth of field.
  • The larger the opening (smaller the f-stop number) the shallower the depth of field.
  • Aperture is one of the most powerful tools in a photographer’s arsenal to creating compelling images. It vital to your photography that you fully understand what changing aperture numbers will do to your photograph.

To the right is a list of typical f-stops you see on modern lenses and a graphical representation of what happens to the depth of field as the f-stop number changes. I highly recommend that you memorize these apertures as it will help you later when you are determining manual exposures and depth of field.

Using Depth of Field to Define your Subject





Depth of Field can be used to bring out your subject.  Take the four images above as an examples.  The right images were shot at smaller aperture where as the left two images were shot with wide apertures.  Notice how the shallow depth of field isolates the subject making it very clear what it is being photographed.

Often times small apertures are good for landscape images but in these cases it cluttered up everything.  

When you are out consider playing around with different f-stops just to see what it does to your subject.