Originally posted by: ElFenix
the S5 has a 6 to 72 mm lens. if you used a sensor twice the size you'd need a 12 to 144 lens to cover the same range. as the area of the lens increases with the square of the length, and weight increases with the cube, you end up with a much larger lens. you probably can't keep the same respectable speeds (f/2.7-3.5) either.
Yup yup. Just to give some more quantitativeness to this:
S5: 6-72mm f/2.7-3.5 (crop factor 6x)
The "f" in the aperture value actually stands for focal length! The value that you get when you do this division is the diameter of the actual aperture opening.
So at 72mm and wide open at f/3.5, the actual diameter of the aperture opening is
72mm / 3.5 = 20.6mm = 2cm = 0.8 inches
With this being said, at least one of the glass elements on the lens of the S5 needs to be at least 0.8 inches in diameter, and the lens barrel itself needs to be at least 0.8 inches (certainly more because of internal electronics/motors crammed inside and the actual housing itself).
Now let's switch to Fuji's awesome P&S sensors, which are bigger than Canon's at 1/1.7" (compared to Canon's 1/2.5" sensors). If Fuji wanted to make a super zoom with the same range as the S5, it would need an
8-96mm f/2.7-3.5 lens (crop factor 4.5x).
Using the same math as above, the lens would need to be at least
96mm / 3.5 = 27.4mm = 2.74cm = 1.1 inches in diameter, but definitely more because of the housing, electronics, etc.
If there was a camera with a sensor diagonal twice the size as the one on the S5, the focal length would be
12-144mm f/2.7-3.5, like Elfenix said. The diameter of the lens would then need to be at least
144mm / 3.5 = 41mm = 4.1cm = 1.6 inches, but more like 2 inches for the housing and electronics.
A 2 inch wide lens is a big lens that's no longer pocketable and harder and more expensive to manufacture. It's hard to justify this for a consumer camera or even a prosumer camera.