What Determines the Depth of Field, DOF, in Film and Video?
The depth of field is a term that you have almost certainly heard before. When describing the scene or set to be captured on camera. If you’re not sure what depth of field is, it’s the size of the area within your image. In which the objects of the image appear sharp and focused. The area represents the “field.” The size of the area is sometimes referred to as the z-space. And represents the “depth.” But what determines depth of field, DOF, in film and video?
Depth of field is determined by the camera sensor. A larger camera sensor will result in less depth of field. And a smaller camera sensor will result in a larger depth of field. Depth of field, When light rays enter the lens, the Depth of Field, DOF, is impacted.
Understanding Depth of Field
Depth of field, DOF, is governed by the angle in which various light rays enter the camera lens and cross the sensor. When a camera with a large sensor is used to capture an image, the depth of field is decreased.
This is because the cinematographer must move very close to the subject in order to fill the frame and, as a result, less light passes through.
The Area Size
Depth of field is described by the field. Which is represented by the area in which objects would appear sharp. And the size of the field, which is depth of the field. The area size is described in terms of z-space.
Within the depth of field, the center most point is represented by the point of focus. This represents the imaginary two dimensional plane which extends from the center point.
Known as the plane of focus. When an image falls within any area of this plane of focus, it is considered to be “in focus.”
What Determines Depth of Field in Film?
In filmmaking, depth of field is determined by aperture, focal length, and distance from the subject. Thus, altering any of these elements can impact your depth of field resulting in a shallow or deep depth of field.
Here’s how each of these elements determines or impacts your depth of field in film:
- Aperture – responsible for controlling the amount of light that enters the camera lens, a wide aperture will result in less depth of field and a small aperture will result in a deep depth of field.
- Focal Length – determines the image magnification with a wide lens, the focal length is shortened and there is a wider depth of field. A longer focal length or zoomed lens will create less depth of field.
- Distance to Subject – refers to the area between the camera and the focus of the image, where the closer the camera is to the subject, the narrower the depth of field and the further away the wider the depth of field.
As you can see, each of these factors impacts depth of field resulting in either a shallow depth of field, medium depth of field, or deep depth of field.
