ABOVE: Oooops! The wagon seems
to switch directions between shots.
(No Sound)
BELOW: Screen direction is consistent
in all 3 shots.
When
editing, you must always ensure that your screen direction
remains consistent. That is, objects in the scene that
move should be going the same direction in every shot.
To
the right is an example from my film "The Oregon
Trail." In the top clip, the wagon seems to switch
directions between shots! That's because the screen
direction of the first and third shot is right-to-left,
but the second shot is left-to-right. Not good.
In
the second clip, all three shots have right-to-left
screen direction.
One
way to ensure you never run into screen direction problems
is to make sure you always stay on one side of a moving
object. That way, your screen direction will stay consistent.
This principle is known as the "180 degree rule."
The
idea is that if you stay within a 180 degree arc, you
won't have screen direction problems. Sometimes students
have a hard time visualizing a 180 degree arc. My suggestion
is to imagine a football game, and stay on the home
team side—don't go over to the visitors, and you
will be OK.
In
fact, it you watch a televised football game, you'll
notice that all the cameras are on one side of the field.
What would happen if they put a camera on the opposite
side? When they showed the shot from the opposite-side
camera, it would appear to viewers that the players
are running the wrong direction. On some national broadcasts,
they DO put a camera or two on the opposite side of
the field. But they use it only for replays--and label
it "Reverse Angle" because it's so confusing.
180
degree rule explained: This animation
looks down on a moving object. The
idea here is to keep the camera on
one side (it doesn't matter which)
and STAY on that side. If you do that,
you won't have screen direction problems.
