Okay so a student in my class asked our teacher why are they called f/stops? My teacher said he really didn't know but his guess was, back in the day when cameras where huge, the photographer most likely had an assistant to help adjust the lens in the front while the photographer would look through the lens. While telling his assistant to keeping turning he would then yell out "stop, right there!" So maybe that is where "stop" was introduced to photography lingo instead of f/step or f/position which I guess seem to make more sense. Anyone have a different theory or agree with my teacher?