Gain in Videography

What is gain in video?  What is it used for?  What are some risks using it?

    Gain in videography, according to the article, is the relative difference between the input and the output video signal. Gain is used for brightening up low lit or dark videos. The way that it does this is by increasing the sensitivity of the camera sensor, amplifying the video signal electronically by increasing the voltage of the pixels. A risk in increasing the gain is that more noise will be visible on camera. This is because by increasing the voltage of the pixels, gain does the same for the noise, making it brighter and more obvious. Because of this, people recommend to use a lower gain and to instead light the subject better.