Factors Affecting Depth Of Field

There are three factors that affect Depth Of Field (DOF): Aperature, Focal Length, and Distance to subject.

• Aperature The greater the Aperature, the shorter the DOF. The smaller the Aperature, the larger the DOF.
  • Set aperature to f/16 to have everything in focus
  • Set aperature to f/2.8 to have subject in focus and background out of focus
• Focal Length The longer the Focal Length, the shorter the DOF. The shorter the Focal Length, the larger the DOF.
  • Use 35mm wide angle focal length lens or shorter to have everything in focus
  • Use 300mm telephoto focal length lens or longer to have the subject in focus and background out of focus
• Subject Distance The shorter the Distance to the subject, the shorter the DOF. The longer the Distance to the subject, the larger the DOF. This is why Macro Photography is difficult, the distance to the subject is often just a few inches. It is important to emphasize that it is not the Macro lens that makes the short DOF, it is the distance to the subject. If a Macro lens were used and the distance to the subject were large, the DOF would be large.
  • Stand 100' from subject to have everythign in focus
  • Stand within a few feet of subject to have the subject in focus and background out of focus

For short DOF:
• Wide Aperature (i.e., f/2.8)
• Long Focal Length lens (i.e., 100mm or more)
• Short Distance to subject (i.e., 5' or less)

For long DOF:
• Small Aperature (i.e., f/16)
• Short Focal Length lens (i.e., 35mm or less)
• Long Distance to subject (i.e., 50' or more)