Comparison photograph of two types of tungsten halogen lamps. The larger lamps is rated at 1000 W 240 V mains voltage. It is suitable for luminaires that light large areas as found in television and film studio production. It is characterised by the larger and thicker tungsten filament. The smaller lamp, at 50 W 12 V, is one of the low voltage lamps having a well defined tungsten filament that provides the small filament field and thus a small source that is necessary in precisely aligned optical systems such as microscope lamps, introscopes and projection equipment. The power supply is usually direct current (DC). Both lamps have the standard GX6.35 base with connection pins at a separation of 6.35mm.