I always like to look at my models as being geometric
planes. If a person is standing facing the camera, the
model’s body creates a rectangle. However, that rectangle is
actually three-dimensional. If you were to measure the fur-
thest body point away from the camera to the closest body
point to the camera, you could determine the depth of the
form.

Now, if the model were to extend her arms outward on
each side, keeping them parallel to the rest of her body, the
width of her form would change, but the depth would not.
If, however, the model were to extend her arms so that one
was in front of her body and the other was behind her body,
the width of her form would not be changed, but its depth
would increase dramatically-it would probably at least dou-
ble from the original width.

It’s precisely this increase in depth that leads to a dis-
torted view of the human body when photographed through
a lens (especially a long telephoto). When working with a
shallow depth of field, you’ll also have out-of-focus hands
and arms if you focus on the face of your subject.