Aperture is the size of the lens opening that can be made smaller or larger. The function of the aperture is to adjust the quantity of light entering the camera. Aperture functions just similar to the iris of an eye. The size of an aperture is known as F-stop. Each lens has a largest aperture like F2.8. The largest aperture allows the passage of most amount of light.
Aperture and F-stop are always in indirect proportion i.e. as aperture increases, F-stop decreases in number and the amount of light entering through the lens increases. This implies that a small F-stop is a large aperture and vice verse. This means that F2.8 is a larger opening than F22.
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