HMI Lights
"HMI" lights have two important features. First, they put out a HUGE amount of light (think searchlight). No other instrument puts out as much light as an HMI. They range up to 18K in size--brighter than three thousand household light bulbs.
Secondly, HMIs put out light that is the same color as sunlight. The result is that HMIs can be used in places where there is a lot of sunlight, without any worries about mixing different colors of light. The downside is that HMIs are expensive and more bulky than other kinds of lights.
HMI's create enormous amounts of light, but that means they need a lot of power. The trailer above is a generator for on-location shoots, because HMI's need that kind of power. Even in locations where power is available, HMIs often need special power tie-ins, because normal wall plugs can't handle the drain of large-wattage HMIs.
