by Cheryl Jones » Mar 25, 2011 9:41 pm
Sorry, I should have explained. The slaves attach to an off-camera flash, either directly or with a short connector wire/cable. They have small sensors built in their nose that detect the light pulse from another flash unit and then trigger the flash they're connected to immediately. Using the suction cup, you can position the slaves anywhere on the flash, or even set them on a rock, so they're aimed towards the master flash regardless of where/how the slave's flash is positioned/aimed.
Slave units are often used to set up multi-flash photos in a cave, or of course when not caving, above ground for an off-camera, wireless, fill-in flash.
Cheryl