Depth of Field (dof) is part of an image that appears sharp (in focus). When composing an image it may be necessary to have the entire image in focus (large dof) and at other times it may be necessary to emphasize only a small portion of an image, such as the subject, background, or foreground, by using a shallow dof.
The 3 factors that determine an image’s dof are:
- Focal length
- Circle of confusion