Okay, I know that these terms are beginning to sound a lot alike, but trust me, they are different enough that ignoring their concepts can cause you problems while editing.
Continuity. This is a big one and encompasses two thoughts.
1) The clock read 3:05 seconds ago and now says 6:10. The bad guy was lying face down, now he’s face up. And Where did the hole in the floor come from? Okay, this one is an obvious thing, and usually occurs during production while being shot. The Script Supervisor is responsible for ensuring that these little issues never happen. They are easy to avoid, but it is amazing how often they will crop up in professional films. There are websites devoted to continuity mistakes.
2) Continuity in editing (which is the concept that we will discuss) is about watching someone walk through a door, and the shot changes and they aren’t as far through the door as they were in the previous shot. They sit down in a chair, change camera angle and they suddenly seem to leap forward in time and are planted in the chair before they ought to be.
So Continuity 101. If someone is walking, they have a rhythm – Left/Right and repeat. If you are cutting from a wide to a close, you must ensure that you got the correct foot coming down at the correct time. You can tell.
A friend of mine insists that the best way to teach editing continuity is to film someone walking to and sitting in a chair, from several different angles and distances – and then cutting it together. It is an oddly complicated thing to do.
How I approach continuity is to think of the action as if it is one shot even if you are seeing it from several angles. If you can watch it as if it is a single action, despite the number of cuts you might make, then you’ve got good continuity. If your character action is not one smooth motion – despite the number of shots – it will have the same effect as taking a single shot, blade tooling pieces out of it, deleting them, and then watching the action. Jump Cut heaven.