It is the ratio of the video signal level to the noise level. This indicator is an important indicator of the quality of cameras. The higher the SNR, the clearer the image, the higher the quality, usually above 50dB.
Cameras are required to work in a brightness (illuminance) light condition, and if the light is below a certain illuminance, the image cannot be seen.
Minimum illuminance (minimum illuminance) is the illuminance required for the image level to reach the specified value when the camera is open to the maximum aperture using maximum gain. Usually in dozens of lux.
such as DXC-537 minimum illuminance: F1.8 13LUX +18dB
F1.4 7.5LUX +18dB
DXC-637 minimum illuminance F1.8 1.5LUX +30dB
F1.4 1LUX +30dB