I'm programming the camera (all layers in comp are 3D) to zoom in and incorporate also some x and y movement. What I find happening is, I will zoom the camera IN to a point in say 3 secs, 0 frames. Then I set another keyframe 2 secs later at frame 5;00 to begin a zoom OUT. Then in frame 7;00 I pull the camera OUT to a diff point.
That movement should look like: camera zooms in, stops at frame 3;00, stays still until frame 5;00, then zooms out until frame 7;00
What I get is what looks like momentum of the camera. During frames between 3;00 and 5;00 the camera moves in slightly until fr 4;00 and THEN moves out again to where it was at frame 3;00 when it reaches frame 5;00. Those frames should have NO movement, yet the camera is moving when I have not programmed it. Why is that happening, the camera should only be reflecting movement that I have programmed into the keyframes. Where is this extrapolation of movement coming from?
Look at your path and check if the keyframes have bezier handles causing the path to bulge out in between the two that have the same position. If so, break the points on the path to eliminate that. I would recommended though using a camera rig to animate your camera. Maltaannon has a great tutorial about that.
@Dave and @Jeremy
these were fantastic tutorials, they answered exactly the question of how to control the camera.
Just one little question more, to put icing on the cake, is there a video tutorial which includes how to easily add easing to the camera controls? That's the only thing needed now to make it really first class.