This question came to me recently…
We have a cannon XHA1 and are having issues shooting dark objects inside. The pixels within the dark areas become noisy or fuzzy. It seems like lower shutter speeds help this issue but don’t resolve it all together.
If you are shooting video in low light and your camera is set to auto iris, the camera will maximize all available light to boost the exposure. This results in grainy, or noisy video. You can also introduce grain onto your video if you increase the camera’s gain to compensate for low light. Many video cameras with manual controls allow you to control the amount of gain, usually in increments ranging from 0db to 18db.
To ensure that your image is clear, sharp and clean, you need to ensure that there is enough light on set for a proper exposure. If your script requires that you shoot nighttime scenes, or scenes in dark interiors, remember that the illusion of darkness is created NOT by taking away the amount of light on set, but by increasing the amount of contrast. You can shoot nighttime scenes without grain by knowing how to properly light the set.