flashed can be triggered several ways -
optically - when they see a flash go off, they go off. Not good at a wedding as the slaved flash will go off everytime grandma takes a picture cause her flash will go off and trigger it.
infrared - the Canon (and others) use this method. The on-camera flash is 'master' and the slave is, well, 'slave'. If the room is too bright or something blocks the line of sight between the flashed the slave may not trigger.
radio - Pocket Wizards (and others) use this method. There is a unit attached to the camera and one on each slaved flash. You can fire one this way from up to 1/4 mile away, outside of buildings with the flash inside, etc. |
