A lens with a low f-number (such as f1.4) focuses much of the light from the scene onto the camera's sensitive Image sensor. In other words, a wide angle lens captures light from all over the scene. A close-up lens (or zoomed in lens) catches the light from only a small part of the scene. In very low light situations, the focal length of the lens (how far it is zoomed in) affects the camera's sensitivity.
The quality of image sensor plays a very important role in its light sensitivity. The quality of the specific image sensor which is used in the camera determines the overall quality of the video output. The size of the image sensor is also important, an Image sensor has small squares or elements that are sensitive to light, so, the more light that falls on these elements, the stronger the signal. The bigger the elements the more light can be collected in a specific length of time.
Reducing the camera’s shutter speed which also decreases the frame rate is another way of increasing camera’s sensitivity. This allows the light to fall on the Image sensor elements for a longer time. Normally cameras make 30 pictures per second. Thus they have 1/30 of a second to collect the light and convert it into a video signal. If the camera made 15 pictures per second, the image sensor would have 2 times as long to "look" at the picture and absorb the light.
RedLeaf uses high performance image sensors as well as advanced image processing techniques to produce high quality images even at low lux levels of 0.005 lux which is near total darkness.