Perszyk+

A 1:1 macro lens has the capability to make objects appear life size on the camera sensor.  My expertise ends there.  My guess this that if you shoot 1:2 then the object appears 1/2 life size on the sensor.  So 1:n equals 1/n size on the sensor.  Just a guess.  The photo of my macro lens shows the focal distance window.  The top line is the 1:n line.  You can see the 1:1 only works on pretty close-up objects.