From the rockpapershotgun side article about leveling
"An example of perks, for the bow and arrow: “one to zoom in, one that also slows down time when you zoom in. Perks also have ranks; maybe there’s two levels of the zoom"
Heres the link if u wanna read it... http://www.rockpapershotgun.com/2011/04/18/skyrim-skills/#more-57393