How far is the most a television camera lens can zoom?

I'm talking professional television camera lens - for example, how far would the Panavision 300x lens be able to zoom? (in kilometres)

It's hard to tell without knowing the exact lens focal lengths. 300x tells me it will have a big zoom, but depending on what sort of lens it has, this could vary greatly

Also, this totally depends on the field of view you're looking for. If you want to zoom in on someone's face, then they will have to be closer than if you wanted to zoom in on, say, a car.