optikamõõtevahendeis valguskiirte teel olev läbipaistmatu vahesein, milles on (reguleeritav) ava, device that allows light to pass for a determined period, exposing photographic film or a light-sensitive electronic sensor to light in order to capture a permanent image of a scene, stop in the light path of a lens, having an aperture that regulates the amount of light that passes, vahesein läätse valgusteel, millel on ava, mis reguleerib läbiva valguse kogust