18000W HMI

Overview

"18000W HMI" (also "18kW HMI" or "18K" for short) does not refer to a single manufacturer's lamp, but to a power class of daylight-white HMI luminaires. HMI stands for Hydrargyrum Medium-Arc Iodide, a gas discharge technology (metal halide) that produces a daylight-like color temperature with high luminous efficacy. At 18,000 watts, this class is among the most powerful single luminaires commonly found on film sets. Typical examples include the ARRI 12/18kW HMI Fresnel and the lensless ARRI ARRIMAX 18/12.

18K HMIs are primarily used to fill in sunlight during exterior and daylight shots, to illuminate large areas uniformly, or to create a soft, large daylight-like source through diffusion frames. Due to their high power consumption and weight, they require an appropriate power supply (generator or robust mains connection) and solid rigging.

Technical Data

The following values refer to the double-ended lamp OSRAM HMI 18000W/DXS, used in 18K Fresnel heads:

The lensless ARRI ARRIMAX 18/12 uses a single-ended lamp with a GX51 base (alternatively G38); according to ARRI, the color temperature is around 5,600 K. The head utilizes a faceted reflector (approx. 646 mm diameter) and allows for continuous beam angle adjustment from approximately 15° to 50° (narrower with an optional spot reflector). The head weight is around 65-70 kg.

Note: The exact values (color temperature, base, reflector size) depend on the specific model and lamp and differ between Fresnel and PAR/reflector designs.

On-Set Usage

18K HMIs are always operated with a dedicated electronic ballast that supports 12/18kW operation. These ballasts operate in the range of approximately 190-250 V AC, provide flicker-free operation, and achieve a high power factor (up to 0.99 with Active Line Filter from ARRI). Due to the high power consumption, an adequately dimensioned power supply is mandatory.

• Types: Fresnel head (with lens, precisely focusable) or lensless reflector/PAR head (ARRIMAX, hard, well-defined shadows).
• Typical Applications: Daylight fill light outdoors, artificial "sunlight" through windows, large-area soft light via diffusion (e.g., bleached muslin or grid frames).
• Handling: Weight and heat generation require stable stands or rigging; warm-up and restrike times of the discharge lamp must be factored in, as a hot HMI will not re-ignite immediately.