Day & Night

MOBOTIX cameras are optimized for brilliant colors in daylight. Since the camera's CMOS sensor possesses good infrared (IR) sensitivity, the portion of IR light has to be filtered out via the lens housing's integral IR blocking filter. Without this blocking filter, the camera would leave certain colors blank; for example, green leaves would be shown in white. IR levels are high at twilight or in halogen light. In order to exploit this IR light to improve the image, MOBOTIX offers a Night version of the lens holder without an IR blocking filter. This can also be used in the daytime, although it does leave some colors blank when used in conjunction with the color sensor.

For this reason, MOBOTIX cameras are also available in Day & Night versions, with two CMOS image sensors (one in color and one in black & white). In contrast to the color function, the camera's night function doesn't possess an IR blocking filter in the lens housing and does have a black & white sensor which is even more sensitive. In twilight conditions the gain on the night function is about a factor of 10. This yields high-contrast night images when combined with the ability to extend the exposure time to a second.

Electronic Switching

Switching between day and night lenses occurs automatically in the secure camera models on an electronic basis, depending on the brightness. This represents a major advantage over other makes of day & night systems which only use a single (color) sensor and switch the filter mechanically. Thanks to their electronic switching, MOBOTIX cameras experience no wear and tear and are virtually maintenance-free.

Lighting

Indoors a 20 sm room can be adequately illuminated with a 10 watt IR LED spotlight for shooting "daylight" images. The best results can be achieved by using indirect IR lighting, pointing towards the ceiling. Where a low level of visible light is not disruptive or is even desirable as emergency lighting, such as in hospitals for example, dimmed halogen light may also be used.

Outdoors standard halogen spots or real IR spots may also be used. Generally speaking, the lighting is more difficult to set up there because a balanced quality of lighting is usually impossible to achieve, and some objects reflect IR light more strongly than others (license plates, faces, etc.). However, if objects only need to be detected, not identified, it is sufficient just to illuminate the area from the camera position. Otherwise, the space has to be illuminated from the side of the camera (> 2 m away) in order to avoid direct reflections.