This article outlines how to troubleshoot IR reflection on a camera.
Listed below are various causes of how IR reflection:
The following image shows an example of IR reflection due to poor gasket seal.
The following image shows the same camera with a proper gasket seal.
Proper camera deployment can help mitigate most of the IR reflection causes. In the case of a dirty dome, a can of compressed air and a microfiber cloth can easily remove dust and other debris.
The most common cause of IR reflection is the lens gasket not being sealed against the dome optic and the IR is reflecting off the interior. This is typically caused by the rubber lens gasket being removed during the camera install. To fix this, make sure the gasket is well seated when putting the dome cover back on. It may be required to take off the gasket and only lightly put it back on the lens. Allow the gasket to compress against the dome when it is closed up.
The following image shows an MV21 with the gasket seated correctly.
The following image shows an MV21 with an improper gasket placement.
The following image shows an MV21 with no gasket on.