If you have installed the camera some time before, it is possible that there are dust collected on the lens and transparent cover.

Please check for contaminants and clean the surface with a clean cloth. Also check whether moisture has entered the lens and cover and remove them accordingly.

Also, the lense focus could be off. Use the focus control lever to check whether to lens focus is off or not.

Hanwha Vision is the leader in global video surveillance with the world's best optical design / manufacturing technology and image processing technology focusing on video surveillance business for 30 years since 1990.