A zoom lens for a camera is adjusted to change its focal length from 38 mm to 304 mm. If
the same amount of light is to be admitted to the lens in both cases, what is the final
f-number if the original f-number was f/2.0?

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The Answer of A zoom lens for a camera is adjusted to change its focal length from 38 mm to 304 mm. If
the same amount of light is to be admitted to the lens in both cases, what is the final
f-number if the original f-number was f/2.0?

A Zoom Lens for a Camera Is Adjusted to Change