>>3765488>Telescopes do it much better, diameter of the aperture is the number that really matters.I think you're fundamentally misunderstanding what f/stops mean?
The amount of light that ends up hitting the focal plane is dependent on BOTH the diameter of the aperture and the focal length, which is what the f/stop represents. The diameter of the aperture ALONE doesn't matter--a 50mm lens with a 50mm aperture is going to let in four times as much light as a 100mm lens with a 50mm aperture.
So the whole point of f/stops is to abstract that away. So a 50mm lens with a 50mm aperture diameter will let in the same amount of light as a 100mm lens with a 100mm aperture, so they would both be f/1.0.
Granted, the f/stop is a *little* bit off from the ideal because physical reality means some light is lost going through the lens elements, but it's close enough for anything other than cinematography (where you're effectively taking 24 photos every second and the exposure needs to line up exactly regardless of what camera/lens that chunk of the movie was recorded at).
