I’m pretty sure it’s in seconds lol 
And to the person who posted this, not sure what you mean but if you want to zoom in on a character you’d need to change the “in 0” part to a number higher than 0.1 (anything between 0.1 and less than 1 second is really fast). In 0 means it will take 0 seconds to zoom on someone, meaning it will be zoomed on them without taking any seconds. “in 5” means the zoom on them will last 5 seconds. “in 3” lasts 3 seconds, “in 7” lasts seven seconds, “in 0.5” lasts 0.5 seconds and so forth.
To read about zooms check out: Zoom Directing (The Art of the Zoom Made Easy)