Focus & Depth of Field

Depth of field (DOF) is the distance in the scene that is in focus at one time. The depth of field range of a camera is determined by its sensor size, lens aperture and focal length. A narrow depth of field could be due to a very large sensor or a wide aperture in the lens. Whereas a wide depth of field is often related to the sensor being smaller or the aperture being narrow or “stopped down”. In subsea cameras, depth of field can be adjusted primarily with a couple of variables:

• Focus Distance: As you focus at a close distance, the depth of field narrows. As you focus at a farther distance, the depth of field widens.

• Optical Zoom: As the lens zooms in on the subject, this has the effect of narrowing the depth of field. From the point of view of the lens, zooming in moves the camera closer to the subject.