[ICA-HM127] Why the screen is so dark?

In this condition, you can try to adjust the DC-iris to optimize the video, please follow the instruction as below:
1) Rotate the adjust screw clockwise to the end.

2) Connect the DC-iris line, put the camera in the dark place.
3) Rotate the screw slowly until the video turn to the temperate brightness, ths is the best DC-iris configuration.