Why the image of one of the camera is blurred.

There could be four reasons to lead to the problem:

1. Irradiation distance is too close, pls try to adjust the angle;  
2. The lens may be blur, you need to disassemble the camera and adjust the focus.
3. Maybe the cable get problem, pls use another working cable and connect the camera to another interface to test.
4. pls revise the output resolution according to the resolution the minitor supports.