HMI (Hydrargyrum Medium-Arc Iodide)
Definition
An HMI (Hydrargyrum Medium-Arc Iodide) is a type of gas-discharge lamp widely used in professional film and television lighting. HMIs produce a very bright, daylight-balanced light (approximately 5600K) that is highly efficient — they produce approximately four times more light per watt than tungsten halogen lamps. HMIs are available in a wide range of wattages, from small 200W units to enormous 18,000W units. They require a ballast (a separate electronic control unit) to regulate the electrical current. HMIs are the preferred light source for exterior daylight-balanced setups and for large-scale interior lighting.
Contextual Usage
The gaffer assesses the lighting requirements for the large exterior scene: "We're going to need at least two 6K HMIs to compete with the ambient daylight and give us enough fill on the actors' faces. I'll position them on condors so we can get them high enough to create a natural sun angle. Make sure the ballasts are on a separate circuit from the camera equipment."
About this section
Production — or "principal photography" — is the phase in which the film or video is actually shot. It is the most visible and, typically, the most expensive phase of the entire process. Every day on ...
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