Then what have you checked based on the 2 following suggestions from members as below?
It was suggested the camera was improperly installed or the camera was mishandled when installing and the lens was rotated from its proper orientation.
It was suggested someone dropped or mishandled the camera when installing and the lens became displaced, knocking it out of focus and making the image blurred.
It was also suggested the dome is dirty; over time UV and smog can permanently fog the image.
My remark was about the reactions, that have nothing to do with my cameratypes. In suggest that people start their own topic, to keep subjects separated.
Some clarification then, Tony:
In previous setup with exact the same camera's, there were settings in the firmware that allowed you to flip and turn the camera image. These seem to have disappeared.
The focus is not related to mishandling, as the blurred image only happen during the night, under IR light. Hikvision suggest that this is caused by bleeding, or straylight, in the dome, by UV.
So I will investigate this.
Domes are clean and undamaged.