| DOF - Depth of Field |
| What is DOF? The Depth of Field is the area in your photo that is in focus. The focus plane is usually parallel to the front of the camera and extends to the edges of the photo. The DOF is the area in front and behind the focus plane that is still in focus and can be a narrow space or a very wide space. The area in front of the focus plane is usually 1/3 of the total DOF space while the remaining 2/3 is behind. The DOF can be paper thin, or go to infinity. This guide will teach you how to control the DOF when taking photos. There are 3 changes you can make that affect the DOF - they are: f-Stop, Lens focal length, and Distance to subject. The f-Stop The f-Stop controls the aperture of the lens. The aperture is the round opening inside the lens and controls the amount of light. A wide open lens at f/1.4 will create a very narrow DOF. A very small aperture at f/22 will have a much larger DOF, however, a small aperture means much less light. Each full f-Stop will cut your light in half. Cutting the light in half means needing longer shutter speed and longer shutter speed raise the risk of motion blur, so you need another solution for controlling DOF. Focal Length The focal length is your lens size from the camera's image sensor to the front of your lens. A wide angle lens will automatically have a larger DOF. Telephoto lens will always have a much smaller DOF. Ultra-Wide lens from 10 to 24mm will have very large DOF. Longer telephoto lenses from 200mm onward will always have extremely small DOF. Subject Distance This is the distance between the camera and your model. Close up photos will always have smaller DOF. Long distance will have large DOF. However, anything past 3 meters is already considered long distance. This is the main benefit to large photo studios. Calculating DOF Yes, there is an exact science to determine the DOF size. For all you math geeks who carry your calculator everywhere (and love you iPhone apps), here is the equation. Otherwise, the DOF Table is much easier to read. You select your camera, the Unit of Measure and the lens length, then press Calculate. Across the top of the table are your standard f-stops. Down the left hand side is your distance from your model. Across the bottom is the hyper-focal distance to infinity. This table is very useful. You can print it out for each of your favorite lenses. |