LED panels with warm white and cool white SMD-LEDs, continuously variable via PWM control between 2700K and 6500K. CRI 90–98, luminous efficacy 100–130 lm/W.
Technical Details
LED Bicolor panels use warm white (2700-3200K) and cool white (5200-6500K) SMD LEDs in an alternating arrangement. The color temperature is mixed between the two spectra via PWM (Pulse Width Modulation) control, with a CRI (Color Rendering Index) between 90-98. Modern devices achieve a luminous efficacy of 100-130 lm/W with dimming from 1-100%. Cooling is passive via aluminum heat sinks or active using fans for outputs above 150W.
History & Development
The first LED Bicolor panels were launched by Litepanels in 2012, after LED technology reached sufficient brightness for professional applications. Aputure established affordable alternatives in the low-budget sector in 2016 with the AL-528 series. The breakthrough came in 2018 with high-frequency LEDs, enabling flicker-free operation at all shutter speeds. Since 2020, app-controlled panels with extended color spectra (RGB+WW) have dominated.
Practical Use in Film
LED Bicolor panels are suitable as fill light in mixed lighting situations, such as interviews in front of windows or in interiors with daylight. In "The Crown" (Netflix), Litepanels Gemini are used as unobtrusive area lights to brighten faces in available light scenes. The continuous light output allows for precise exposure control without test shots. Disadvantages: limited light output compared to HMI lights and color shifts at extreme dimming below 10%.
Comparison & Alternatives
Unlike monochrome LED panels, there is no need to change filters between Tungsten and Daylight, saving time. RGB LED panels offer more color options but achieve lower brightness in white. Classic halogen spotlights with CTB/CTO filters lose 50-70% of their light output, while LED Bicolor only loses 5-10%. Modern RGBWW systems like Arri SkyPanel are increasingly replacing pure Bicolor units as they cover the entire color spectrum with comparable efficiency.