In a nutshell what is depth of field?

The term ‘Depth of field’, or DOF, refers to the depth of an image in focus, in a given video.  There are two types of depth of field; shallow and deep.  A shallow depth of field would refer to a shot, where the object or person is in focus with the background blurred.  On the other hand a deep depth of field would keep the whole image in focus, allowing the viewer to clearly see both the foreground and background.

picture example of depth of field

What specialist equipment, expertise or processes are involved?

No specialist equipment is needed for achieving your preferred depth of field.  The main thing to consider would be your choice of lens.  There are several ways that you can adjust a lens to alter the depth of field.  Firstly through the focal length.  In basic terms, the more zoomed in a lens is, the shallower the depth of field will be.

You can also adjust the F Stop settings, which allows more light to pass through the lens, also making the depth of field shallower.  Often cameraman will adjust both of these settings to achieve the desired focus.

DOF example flower shot

When shooting in well-lit locations or in exteriors, a camera with an ND filter is helpful. This filter is in camera behind the lens, still allowing as much light as you would like through the lens, but keeping you from over-exposing the image.  Some basic or DSLR cameras do not come equipped with an ND filter, but a separate detachable filter can be obtained which acts as sunglasses for your lens.

Depth of field is achieved completely in production, there is little work that can be done in the edit suite to adjust what has been shot on location.  Blurs can be added to background image to fake a shallow depth of field, but this often can look obvious and therefore becomes ineffective.

close up of camera lens

Why should I consider using depth of field in my video production?

You will always use depth of field in any video production, the question is what type of DOF does your video need?  Shallow depth of field lends itself more towards filmic type of productions and definitely adds a nice bit of production value to any video.  Alternately, deep depth of field is more effective with fly on the wall style documentary videos, allowing the viewer to completely grasp everything that is happening within the scene.

Summary

Depth of field really depends on what you desire from your video production.  There are definite advantages to both options but the best way to use depth of field is to move between shallow and deep focus depending on the shot.  Having a great mixture of shots throughout your video can add fantastic production value.