Quote Originally Posted by Claire Senft
It is probably a good time to explain what an fstop means. F stands for fraction.
Not quite. "f" (lower case) is the standard symbol for focal length.
Properly, the aperture should be written as "f/stop" Where "f" = focal length divided by "stop" = aperture diameter.

It is a ratio. Equal numeric f/stops transmit equal amounts of light.