Phantom Flex High Speed cinematography has a sweet spot at 1000 frame per second based on the human body's reactions to motor movement. Close-up framing using any high speed camera of the human face at 1000 frames per second is actually not pleasing and can result in a negative audience reaction.
High Speed Cinematography has 2 big issues in terms of lighting - exposure and flicker.
Camera ISO is recommended by the factory but you can stretch the sensitivity of the camera if you have a camera that has a high dynamic range and low light sensitivity without video noise or gain in the blacks. One way to do this is rating the camera to 1200 ISO and boosting the toe of the sensometric curve. The Phantom Flex 4K can be “pushed” easily without noise. The other way to increase exposure is using a wider shutter opening than 180 degrees. What becomes a creative choice at 24fps is greatly reduced by the very nature of 1000 frames per second.
The second big issue is flicker from lights. All tungsten lights less than 2000w flicker including Maxi Brutes and Maxi Fay lights. The “Maxi” lights have many lamps from 600w-1000w which added together can be up 9000w but it always goes back to the individual lamp which has to be 2000w or high. Even a 2000w lamps may flicker and needs to be tested. All 5000w or 10,000w tungsten lamps are never a problem.
All HMI’s will flicker including the "flicker free" High Output ballast HMIs. LED lights will not flicker if you do not use a dimmer up to 1500fps but their foot candle output is still low for most high speed.