Many types of artificial lighting flicker at twice the rate of the power source. This is most pronounced with fluorescent lighting, but also happens to a lesser extent with incandescent. Common power sources are 50 Hz (in Europe and most of Asia) and 60 Hz (in North America), which cause 100 and 120 pulses of light each second, respectively.
Other than changing the lighting, one has two options for overcoming this problem:
Frame Rates. Choose a frame rate equal to the lighting pulse rate divided by some integer. This is often the simplest option since most corresponding shutter speeds will appear flicker-free.
Shutter Speeds. Choose a shutter speed equal to the lighting pulse rate divided by some integer. This option often isn’t as straightforward, and can constrain one’s ability to control motion blur. On the other hand, this option typically minimizes flicker under a broader range of lighting and power types.
For example, in North America, the standard 24 and 30 fps settings work with most shutter speeds (since 30×4 and 24×5 = 120). Use the tool below to find other flicker-free shutter speed and frame rate combinations: