Vertical FC is provided by the room...not the cam. There is no spec for min Vertical FC.
However we do have a low min lux spec as well as built-in dynamic range control and noise suppression. The end result is a good image in low and mixed light.
The old VTC spec for lighting was shoot for 55 fc with a 3:2 contrast with subject background. The PTZOptics is far more forgiving than that. We have a .5 lux lighting requirement to give us enough to produce a 1920x1080p image on our CMOS sensor.