Lighting for High-Speed
Lighting issues are not specific for the Phantom cameras but for high frame rate photography in general. Even with the great sensitivity of modern cameras, be prepared to use a considerable amount of light. Beyond illumination, the largest issue in high-speed lighting is flicker. Tungsten lights actually have a flicker rate. When powered by alternating current (AC) electricity, the power cycles 50 or 60 times per second (depending on the country and its power system). During the down cycle the tungsten lamp filament can dim slightly, causing flicker. The amount of dimming is related to the type of bulb, wattage and physical size of filament. In general, we have found that lamps larger than 2000 watts use tungsten filaments so large that they do not have time to cool and dim before the power cycles back up. Therefore, we recommend using 2K or greater tungsten light fixtures when shooting above 120fps (100fps in 50hz countries). Be aware that a nine-light is NOT a large light but is actually an array of smaller light and as such can flicker.
Some additional recommendations are to use DC power for tungsten lights, which eliminates flicker entirely. HMI and fluorescent lights are generally fine for speeds under 120fps as long as they use electronic ballasts. Magnetic ballasts should not be used. HMI lights can suffer from “arc wander,” whereby a plasmatic “hot spot” can move about within the bulb, causing an amorphous shifting movement in the light output. LED lights are subject to the electronic circuits driving them and are subject to a vast array of refresh rates. Finally, the shutter angle on the Phantom can affect flicker as well, as a greater shutter angle allows for a longer response time from the light. When shooting extremely high frame rates, it may no longer be necessary to retain a 180-degree shutter to capture the motion generally preferred for a filmic look. A 360-degree shutter allows both more light sensitivity and reduced flicker possibilities.
Lighting for High-Speed : Phantom
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- Paramvir Singh
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