By now you should have a pretty good grip on the different forms of photography lighting equipment. We've discussed several types of lamps for studios and today we'll wrap up with HMI lights. HMI stands for Hydrargyrum Medium-Arc Iodide. The H is better known as Mercury and the I is a halogen used in the lamp. HMI lighting is more predominately seen in the motion film industry as opposed to photography. One reason being that they are rather large and expensive, but they serve their purpose well.
HMI lighting offers consistent color temperature, are flicker-free, cooler than other lighting, and produce a high quantity of light. The color temperature will remain consistent up to about 500 hours of use before you begin to notice more green in the light. HMI lights are not actually considered a “cool” light, but they typically run cooler than tungsten lighting.
When used in studio photography, most choose it for portraits and stills. They offer many of the same advantages as tungsten lighting, but because they run a bit cooler, they are easier to use with softboxes, scrims, and other light modifiers. Despite the higher price tag, HMI lights remain a popular choice among film makers and photographers.