Accessory flash slave units are available to fire multiple flash units without multiple electrical connectionsto the camera. These units sense the light output of the first flash, which is mountedin the camera hot shoe, or cord-connected to the camera. When the light output issensed, the slave unit triggers a second flash unit that is connected only to theslave. Additional slaves and flash units can be used, if needed.mirglossary
Also called Slave Flash or Photo Slave. A light-sensitive triggering device that is built in or attached to an electronic flash unit, causing the flash to fire simultaneously with another flash unit.
A strobe that fires when it sees another strobe fire (optically or electronically).
Electronic flash which responds to commands of prime or main flash, e.g. triggering its flash when main unit flashes.
A unit that, like a perfect assistant, responds in a flash to the Master.