What is the difference between depth of field and depth of focus?

Question

Reading this answer I realized that I didn't know the difference between the two depths (of field and focus). Browsing related questions didn't reduce the blur (!) between the two...

Wikipedia provides a discussion which is helpful but I think that it could be useful to clarify the distinction between the two here in more detailed terms (e.g. physically they are not the same effect but does this really affect the final result? Is the confusion really misleading?)

Answer 1

Depth of field tells you the range of distances from sensor/film where your subject can move in scene so it would still remain in focus.

Depth of focus is used in two slightly different meanings . It tells you the range of distances from lens where your sensor or film can move so

• the same object plane would still remain in focus;
• or, the same subject would still remain in focus (this depends on placement of subject - greater on edge of image).

Depth of focus is usually much less than a millimeter and becomes relevant when

• your camera does not correctly tension film against back wall of the camera,
• or you are using bellows between lens and film/sensor,
• or you are freelensing,
• or you are using a lens which has bellows as part of its construction, such as Lensbaby Muse.