Shortly after we get our first speed light style flash, we realize that photos made with the flash mounted on the camera can look flat and harsh. So we want to get the flash off the camera. Fortunately many OEMs build some type of remote control capability into some of their cameras, but sadly not into all of them. This type of remote control uses the pop-up flash to communicate to the remotes via Infrared signalling. When it works, it’s awesome, but as this mode requires a direct line of sight between the camera and the other flashes, there’s an element of chance of failure.