Zooming from characters please help!

Does anyone know how to zoom on a characters face, and then zoom onto a different characters face, and it move back and forth from the two characters?

Heres a guide on basic zoom directing:

When you want sort of a pan zoom effect, then you have to add a timer on the zoom.
For example:

@zoom on X Y to % in 2

The zoom will take 2 seconds to finish, therefore it will move instead of just automatically switch around on the screen.

Thank you!!