High Speed Ballast: electronic ballast for HMI lamps operating at 200 Hz frequency, eliminating flicker artifacts in high-speed cinematography above 200 fps.
High-speed ballasts operate at 100 Hz with 230V/400V mains voltage and generate a light frequency of 200 Hz through AC half-waves. Available power ratings range from 575W to 18,000W for corresponding HMI lamps. The unit uses an electronic igniter with up to 45,000V ignition voltage and precisely regulates the lamp current to ±2%. Modern units additionally offer hot-strike functions for immediate re-ignition after a brief outage.
Three main variants exist: Standard High Speed Ballasts for continuous operation, Flicker-Free Ballasts with an additional 1000 Hz option for extreme slow motion, and electronic ballasts with DMX control for remote dimming.
Arri developed the first commercial high-speed ballast in 1993 for the 2.5K HMI, after cinematographers complained about disturbing flicker effects during phantom recordings at 1000+ fps. In 1997, Osram introduced corresponding 6K and 12K versions. Electronic Theatre Controls launched the first DMX-controllable models in 2001. Since 2010, manufacturers like Dedolight and K5600 have also offered battery-powered high-speed ballasts for mobile applications.
In "The Matrix" (1999), cinematographer Bill Pope used high-speed ballasts for the bullet-time sequences at 12,000 fps to ensure even illumination without flicker. Sports and commercial filmmakers use them as standard with Phantom cameras – for example, in Coca-Cola commercials with splashing liquids at 5,000 fps. The higher acquisition cost of 40-60% compared to standard ballasts is offset by savings in post-production, as no flicker correction is necessary.
Standard ballasts with 50 Hz cause visible brightness fluctuations when shooting above 200 fps. LED panels with CMOS-optimized control are increasingly replacing HMI setups, but do not yet offer the light output of large HMIs. Xenon lamps with DC operation are completely flicker-free but require special projectors and do not achieve the color temperature consistency of HMIs.
Ich setze High Speed Ballasts ein, sobald die Aufnahme über 200 fps geht – das spart mir Stunden in der Post, weil ich keine Flicker-Korrekturen machen muss. Bei Zeitlupen-Produkten für Automotive-Kunden sind die Dinger unverzichtbar, sonst sehe ich das Flackern sofort im Monitor und muss neu drehen.
Für mich bedeuten High Speed Ballasts kreative Freiheit bei Zeitlupen-Sequenzen – ich kann spontan entscheiden, ob eine Einstellung in 1.000 fps funktioniert, ohne dass der Kameramann über technische Probleme klagt. Bei Actionszenen spare ich Zeit, weil wir nicht wegen Flicker-Problemen wiederholen müssen.
Die 8.000 Euro Mehrkosten für ein 6K High Speed Ballast zahle ich gerne, wenn dadurch zwei Drehtage mit Phantom-Kamera flüssig laufen. Rechnet sich sofort gegen die Alternative: Standard-Equipment mieten, Flicker in der Post korrigieren und dabei Bildqualität verlieren – oder schlimmer, nachdrehen müssen.
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