OK, I have read articles about this for days, now let's see if I understand...
This rule is used to help expose properly. The idea is that if it is sunny you set shutter speed to match ISO, and aperture at f/16. From there you would make adjustments based on what you are shooting.
For example, lets say I am shooting with aperture of 22, then I would take my shutter speed down by two stops, so instead of 350 (iso 400 film, my camera has no 400 shutter speed), i would use 180??
Am i understanding this right??