Working with Canon Speedlite flashes can be both a blessing and a curse. It’s a blessing because these wonderfully intelligent devices can deliver just the right amount of light into your scene, working with the camera to figure out the correct exposure in the fraction of a second after you press the shutter button. It’s really quite miraculous. On the other hand, it’s a curse when you struggle to understand how to operate these flashes based on the cryptic instructions in the manual, and you find yourself pulling your hair out in frustration when it doesn’t work. This happens all too often. One of the more confusing settings on the Canon 580EX II flash is Master Mode. This is the mode where the 580EX on your camera becomes the master, or controller, of other remote flashes. The remotes might be additional 580 EX flashes, or simpler models like the 430EX. In order to control the remotes, you have to get the master flash set correctly, and this can be confusing, to say the least. The first confusion arises because Canon chose to initiate the Master setting by having you push the Zoom button on the flash. Not the Mode button, which would have made sense, but the Zoom button. Once you push the zoom button and hold it down for 2 seconds the flash enters Master setup mode. The second confusion arises in this mode when you see the words On and Off. These words can mean different things when it comes to a flash. For example, when I set it to Off, am I turning the flash itself off as a light source, or am I merely turning off its Master function? (The answer it the latter). If you want to turn the flash itself off as a light source, so that the only light in your scene is coming from the remote flashes, that’s an entirely different setting, which we’ll talk about another time. Just understand this. Once you hold the Zoom button down to enter the Master setting mode, the meaning of the terms On and Off only apply only the the state of the Wireless Flash mode, the Master mode of this flash. If you turn it Off, you are turning Off the function of this flash as a Master. In that case, you care actually turning On the flash as a regular, stand-alone flash. It’s not wonder photographers pull their hair out trying to understand this. The terminology lends itself to ambiguity and the choice of buttons on Canon’s part was less than crystal clear. And of course the manual for the 580EX II flash is a typical camera manual, brief, cryptic, and probably written by someone who spoke English as a second language. If you’d like to see an actual demonstration of this flash setting, you want want to view the detailed video illustrating this technique on the website SteeleTraining(dotcom). In that video you can actually watch this process performed hands-on with the flash, and sometimes a picture (especially a moving picture) is worth 1000 words.