Question by -Mersadies-: Why does aperture go up with zoom?
Why does the aperture go “up” (in number) when I zoom? Is there a way to keep it the same no matter what length the lens is at?
Answer by Sakura
The aperture is the opening that determines the amount of light a lens will let through. The amount of light let through is also dependent on the quality of the lens. It turns out that when the focal length gets larger, this opening also needs to get larger in order to let in enough light to expose the image. This is because the amount of light gathered by a telephoto lens is spread over a larger area, thus making the brightness less.
There is no way to keep it the same.
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