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.
Below 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.
In these two examples you can clearly see the difference that changing the f-stop makes. Each image has a different feel. Be sure to keep the depth of field in mind the next time you are out shooting.