This is a somewhat tricky set of problems, so I made a simple example file to test out some ideas.

In the first test, I simply attached ("parented") the camera to the upper stage so that it follows it. I thought this would be really boring, but the changing light creates an interesting effect. This is also reminiscent of footage from cameras mounted on spacecraft (even though of course this particular shot couldn't be done that way).

In the second test, I parented a Bezier curve to the upper stage and animated the camera along it. I then used tracking constraints for both the upper and lower stage to get the camera to try to keep both in frame. Unfortunately this sometimes means the camera is looking at the empty space between them.

In the third test, I moderated this by defining IPO curves for the influence of the two tracking constraints. This way the camera can be set to follow one or the other stage at the appropriate points along its track. A little trickier, but it works.

None of these motions is really "physical". Ideally, I'd like to set angular and linear velocities. That would create more realistic movement, at least for stages separating in vacuum and zero-gee conditions. I might try some kind of simulation approach later.

I'll be applying what I learn from this to work on Lunatics!.

CC By-SA 3.0

Music: "D10-2000" by Gregoire Lourme, same license.