Day-Night and IR Surveillance Cameras
The main feature you must be looking in security and surveillance cameras is the clarity of image, whether it is day or night. Problems come in recording videos during night or in darkness. Cameras depend on the available light for recording of clear images. For night recording, cameras can be Day/Night camera (True and Digital) or an IR camera.
This camera allows taking pictures in day and night with minimum illumination. It can be True Day/Night camera or a Digital Day/Night Camera.
True Day/Night cameras
make use of mechanical switching IR Cut Filter. This filter is placed in front of camera lens during day time to filter out the IR rays which otherwise will distort the coloured image. These IR rays are coming from the sun or being reflected by the objects.
Although humans cannot see these rays but some cameras are sensitive to IR rays and capture them. At night, these filters are removed automatically and allow the cameras to record the images without any IR illuminators. It allows more light into the images to deliver a clearer picture and minimizes distortion in black and white mode.
Digital Day/Night cameras
Dot not use IR filters. They electronically adjust the colour of image at day time and when light gets dim, it switches to night mode and starts recording image in black and white. So they are providing the same performance as True Day/Night cameras but at low cost and can be leveraged for smaller form factors for instance, the bullet cameras.
The quality of images produced by the camera depends upon the LUX rating. The lower the value of LUX will be, better the results of camera during night time. This is something to be kept in mind while buying them. Always check the LUX rating that whether it is matching your requirements or not. Depending upon LUX ratings, some cameras also work well in dim moon light and ambience of stars.
IR cameras, have an array of LEDs around their lens emitting infrared rays. These LEDs turn on in low light and help in producing clear black and white images. So these cameras give normal quality at day time and illuminating images at night.
The important thing to note about IR cameras is their range. You have to check that how long these infrared rays are being shot.
The camera cannot capture the details of objects beyond its range. It isn’t that objects will not be visible but there will be fewer details. In case you want to see beyond this range, you have to adjust the focal point of lens but it will shorten the coverage area. Mostly it ranges from 15 meters to 70 meters and these infrared cameras operate in wavelengths as long as 14,000 nm (14 µm) whereas the visible light cameras range is 450-750 nm
There are some cameras that come with IR LEDs and IR filters too such as GeoVision GV-BL110D. While buying a surveillance camera, make sure that you have checked LUX rating and IR LEDs range. These two factors greatly affect the images taken at night.