Hik Vision in the past two years has improved the specifications reporting by specifying in most cameras (not all) the Horizontal and vertical field of view angle.
However, the still do not specify the f capability of the lens, that is the aperture of the lens. Therefore the minimum illumination specified usually is the minimum illumination of the sensor and not of the camera. For example the at f1.2 the sensor may have a minimum illumination of 0.001 but if the lens fitted is f1.6 (a typical medium quality lens) then the camera minimum illumination is 0,01. This now should not be considered a low light capable camera. The color VU line of cameras are advertised in some you tube videos of having f1.0 lens which is the ideal aperture (everyone with some photography experience knows that it is impossible optically to achieve f1.0). In this case the minimum illumination reported in the specifications can be considered as truly reported. In all other cases, the specifications of the minimum illumination are not always reported properly.