1. How the lens reflects and refracts light This is usually at the point where the light originates

2.  Is the distance between the nearest and farthest objects in a scene that appear acceptably sharp in an image.  Depth of field is the front-to-back range of focus in an image — that is, how much of it appears sharp and clear.

3.  cinematographic technique using a large depth of field.  Depth of field is the front-to-back range of focus in an image — that is, how much of it appears sharp and clear.

4.  A technique incorporating a small depth of field.  Depth of field is the front-to- back range of focus in an image — that is, how much of it appears sharp and clear.  In shallow focus one plane of the image is in focus while the rest is out of focus.  Shallow focus is typically used to emphasize one part of the image over another.

5.  Shifting the attention of the audience of a film or video by changing the focus of the lens from a subject in the foreground to a subject in the background, or vice versa.

6.  a method of decreasing (narrowing) the apparent angle of view of a digital photographic or video image.  Digital zoom is accomplished by cropping an image down to a centered area with the same aspect ratio as the original.

7.  to make an object appear farther away, closer, larger or smaller than it actually is.  It manipulates human visual perception through the use of scaled objects and the correlation between them and the vantage point of the spectator or camera.