Nightshot
Nightshot is a process introduced by Sony that enables photos and video cameras to be used in the dark.
The sensitivity of cameras goes beyond the spectrum of light that is visible to humans . Cameras often have infrared cut filters so that this does not lead to color distortions in the recorded images . With nightshot cameras, this filter can be folded away mechanically, so that the total amount of incident light increases. Furthermore, the colors are not recorded individually, but summed up to form a black and white image (which, however, is recorded as a green-black image), the aperture is opened to the maximum and the exposure time to the maximum value of 1/50 ( PAL ) or 1/60 ( NTSC ) seconds increased. It is also possible to combine several consecutive images in order to further increase the light output, but this leads to strong trailing effects.
The principle is based on the fact that wherever there is a light source (candle, incandescent lamp, ...) it also emits infrared light. If the visible part of the light is no longer sufficient in a situation, the infrared part can compensate for this deficiency to a certain extent. A built-in IR emitter (range approx. Three meters, can be extended with external emitters) ensures that night shots are possible even in lightless rooms. In contrast to high-quality night vision devices, the nightshot mode does not have any significant light amplification. In contrast to thermal imaging cameras, the infrared rays emanating from every object cannot be recorded.
Nightshot is also used by voyeurs , as some surfaces (fabrics, plastic films) are opaque in the visible range, but transparent in the infrared range. An infrared filter is also used to prevent the visible color of the object from shining through. In contrast to the filter mentioned above, this is not a filter that allows visible light to pass through and blocks infrared radiation, but a filter that only lets this through.
Sony differentiates between Nightshot , Nightshot Plus , Super Nightshot and Super Nightshot Plus . Nightshot Plus does not need to get used to the green in the picture, Super Nightshot is more sensitive than the standard Nightshot .
Others
Some cameras do not have an infrared cut filter at the factory: e. B. surveillance cameras or a variant of the Raspberry Pi camera ("NoIR"). With these, the infrared light has a disruptive effect on the color rendering (if available).