In some implementations, the lens assembly 704 includes a cover glass 705, a camera lens structure 1132 and an infrared filter 1134. The IR filter 1134 is activated in the daytime mode for precise color reproduction, and disabled in the night mode for greater light sensitivity when the field of view of the doorbell camera 106 is illuminated by the IR illuminators 1105. Optionally, the ALS assembly 714 is also used to cause switching between the daytime and night modes, and enable/disable the IR illuminators 1105 and the infrared filter 1134. In some implementations, the lens holder 1120 is supported by the infrared filter 1134 to protect lenses in the lens assembly 704 from being pushed when a user touches or presses the front cover plate 708. The doorbell camera 106 may include at least a sensor board 1108, a main board 1110 and a secondary board 1112 that are stacked within the device housing 702. In some implementations, the sensor board 1108 includes a connector 1108A that is coupled to another connector of the main board 1110 directly. Alternatively, a flexible cable is optionally connected to the connector 1108A for electrically coupling the main board 1110 to the sensor board 1108. In some implementations, two ends of a flexible printed circuit FPC 1126 are electrically coupled to a respective connector at the main board 1110 and the secondary board to couple them to each other. The sensor board 1108 optionally sits on a rear interior surface of the device housing 702. An image sensor array 1114 may be disposed on top of an end of the sensor board 1108, and the lens assembly 704 may be further disposed on top of the image sensor array 1114, such that light passing through the lens assembly 704 arrives at the image sensor array 1114 to form an image captured by the image sensor array 1114. In some implementations, the sensor board 1108 includes an image processor.