The Optical Barrier
Crossing the LineA great subject for film buffs this one. It’s so simple, but it catches us all out at some time. It’s just a matter of helping your viewer tune in to each new shot as quickly as possible. If your cuts are invisible, he or she will be able to get on and enjoy the story. If you confuse him he’ll probably get fractious. And if he’s watching television he might reach for the remote… You’ll hear directors talk a lot about “crossing the line’ or the ‘optical barrier” and it all sounds jolly mysterious. Actually it’s not at all complicated in principle. Remember the hat owner and the nose proprietor? Here they are again:
They’re looking at each other. Or to be more exact, one is looking left and the other one right. So they appear to be looking at each other. It’s more or less how you’d see them with the eye.
The camera positions would be like this:
The camera positions would have been like this:
Car ChasesThere’s a similar sort of problem when you”re shooting any means of travel. If a car is going from left to right in one shot, it should continue that direction of travel in the next. If a man is walking from his front door to meet a friend and he”s going right to left, then when we see him arrive at where the friend is standing, he should still be moving right to left. It”s even more important to be careful about direction of travel if you”re shooting a chase. For example, can you imagine these two shots cut together?
There are many ways to make a car change visual direction.
Here’s one way to do it in the middle of a shot: