"Many burglars first ring at the door to find out if anyone is in", confirms Chief Inspector Wilfried Jasper of the Stuttgart Criminal Investigation Bureau. Bad luck for thieves if they happen to be standing in front of a video intercom system with video memory. The door cameras on these systems automatically take a picture every time the bell is rung. Just like a telephone answering machine, the video memory module records who rang at the door and when. Once the module is full, the oldest picture is overwritten.

A particularly clever twist: The deluxe models of the Siedle video telephones are fitted with an insert for external memory cards. This increases the capacity to a maximum of 255 pictures; the standard internal memory is capable of storing 28 photos. And with the card it is also simplicity itself to transfer the pictures for instance to a PC and save them permanently – or if the worst happens, to hand them over to the police. The darkness coveted by burglars is not an impediment, as high-quality door cameras have their own built-in lighting, and the top models even work with an automatic day/night switchover facility. In darkness, they switch over to the monochrome photography mode, making for markedly enhanced sensitivity. In this way, clearly recognizable portrait images are produced even under difficult lighting conditions.

Tip: Day/night switchover facility is something of an elastic term. Note the specifications, where light sensitivity is specified in Lux. The smaller the value, the greater the sensitivity. The Siedle camera switches over to true monochrome mode and achieves a sensitivity of 0.08 Lux. This is better by the factor 10 than a simple monochrome reproduction - which is frequently claimed by manufacturers to be day/night switchover.