Another kind of metal halide lamp is the halogen metal iodide or HMI lamp. It is mainly used for photography since it makes a 5600 K light (matching natural daylight) and has a great CRI. The lamp has a optimum combination of metal halides made of rare earth metals. It has a quartz discharge tube with rod-shaped electrodes made of tungsten and a power supply of high voltage DC. The external ballast is rather heavy, about 6+ pounds. The light is best used as a powerful light source at 8+ ft (2 m) distance from the talent. This light is expensive and in demand among the film and television industry professionals. 90 lumens per watt.

What is metal halide lamp?