From time to time we receive support requests from customers who claim that the camera is no longer able to deliver good images at night. Among the most common symptoms, customers report blurred and/or dark images. The cause of such problems oftentimes lays in the lighting conditions and in the camera configuration.
CCTV systems based on optical imaging sensors need light in order to operate, weather it is visible or IR light.
MOBOTIX offers different types of sensors:
- Day: color sensors with IR cut-off filter, therefore sensitive only to visible light.
- Night: b/w sensors w/o IR cut-off filter, sensitive to visible and IR light.
- LPF: b/w sensors with visible light cut-off filter, therefore sensitive only to IR light (specific for ANPR applications)
Dealing with no-light situations? No problem! Thermal technology is what you need. Read more about how thermal sensors along with MxActivitySensor can help you detect movement in pitch-dark scenes.
If the camera is not able to produce sufficiently bright images at night, it’s important to determine the amount of illumination detected by the image sensor.
MOBOTIX cameras allow you to display the illumination level and the exposure time directly on the live image. To do so, go to Setup Menu > Text & Display Settings and add following text to the “Comment” text box:
Illumination Right sensor: $(SEN.LXR) Illumination Left sensor: $(SEN.LXL) Exposure Right sensor: $(IMG.EXP.RIGHT) Exposure Left sensor: $(IMG.EXP.LEFT)
If you notice that the illumination level is < 1lux, you should consider adding artificial light because the scene is too dark. When you choose the illumination please keep into consideration the type of sensor(s) installed on your camera.
Check whether or not the artificial light (if any) is working properly. While it’s easy to verify devices that work with visible light (e.g. lamps), it might be more challenging to verify IR light as it is not visible to the naked eye.
For semi-discrete light illuminators (850 nm), however, it should be possible to see a red halo on the LEDs when the device is on.
For discrete light illuminators (>920 nm), the only way to verify the device is by using a sensor without IR cut-off filter; a common method consists in pointing the camera of a smart phone in the direction of the illuminator: if the IR is on, a faint light should be visible on the screen of the smart phone.
Make sure that the illuminator is pointed to the part of the scene you want to illuminate; in fact, if you use spotlights or illuminators with a narrow beam, it’s possible to “miss the target” and illuminate a part of the scene that is not covered by the camera field of view.
Finally, if are sure that the scene is properly illuminated, but you still cannot obtain a good image, you should check the camera configuration: for instance, if amplifiers have been turned off, the resulting picture could be extremely dark. If you still get motion blur, instead, you should reduce the Max Exposure Time. To make everything easier we recommend to bring the Exposure Settings back to factory default by pressing the “Factory” button within the page Setup Menu > Exposure Settings. After that you can adjust (if needed) settings like exposure time, sensor gain, night improvement and minimum average brightness.