The magic of the slow-motion replay is that it makes the big, split-second moments in sports accessible to fans watching the game in the stadium and at home. While the quality of the play is determined by the talent of the athletes, the quality of the slow-motion replay is dramatically affected by the venue’s lighting.
The relationship between slow-motion replay and high-speed capture
Slow-motion playback starts with high-speed image capture. As cameras increase the frames or images captured per second, replays are able to reveal greater levels of detail about what occurred during the micro-seconds of that magic moment.
Today, 120 frames per second (fps) is considered baseline slow motion, moving at a quarter of the speed of real life. As capture rates surpass 300 fps, slow-motion replays can create a truly unique viewing experience, allowing people to see the details of the field or the court and the players in a whole new way. And 300 fps is far from the fastest possible frame rate; professional cameras that can capture between 2,000 and 10,000 fps already exist.
The relationship between high-speed capture and flicker
Unfortunately, higher frame rates are more likely to detect the oscillations in the output of the sports lights and capture a different level of illumination from one frame to another. It is the frame-by-frame changes in light level that create a flicker or strobing effect in the slow-motion replay. For flicker-free playback, each frame captured by the camera must be exposed to the same amount of light.
Generally, traditional metal halide sports lights cycle too quickly for the difference in output to be detected by the naked eye, but not quickly enough to accommodate frame rates of 300 fps or more. Footage recorded at 300 fps underneath metal halide systems will often exhibit flicker when replayed in slow motion, and the problem only gets more pronounced as the capture rate increases. Sports venues with metal halide systems are often limited to recording at frame rates lower than 300 fps to ensure that the replay is flicker-free.
How LED technology contributes to flicker-free replay
The key to capturing split-second sports moments that can be relived in flicker-free slow motion is finding sports lighting fixtures that can provide adequate and even illumination to every frame, even as the camera’s frame rate increases. Advancements in LED sports lighting technology address the deficiencies of metal halide, making it possible to record at rates of up to 2,500 fps with smooth and flicker-free playback.
This dramatic improvement in slow-motion replay is a result of increasing the rate at which the LED lights cycle and staggering the cycle within each fixture, effectively camouflaging the differences in light output from one fixture to another. These LED fixtures can oscillate at a frequency that ranges from 20,000 to 40,000 Hz, meaning that a camera recording at a frame rate of 2,000 fps will receive at least 10 pulses of light for each frame. This amount of light on each frame is sufficient to avoid flicker when the footage is replayed in slow motion.
Sports venues with these advanced LED lighting systems can offer audiences in the stands and at home exciting and flicker-free replay in a level of detail that was not previously possible with traditional sports lighting systems.