HIKVISION DS-2CD4A26FWD-IZS/P User Manual page 7

the dome cover, clean the dome cover with clean soft cloth and isopropyl alcohol.
 Make certain the installation location does not have reflective surfaces of objects
too close to the camera. The IR light from the camera may reflect back into the
lens causing reflection.
 The foam ring around the lens must be seated flush against the inner surface of
the bubble to isolate the lens from the IR LEDS. Fasten the dome cover to camera
body so that the foam ring and the dome cover are attached seamlessly.
Network Camera User Manual
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