If there is another Canon wireless flash system nearby, you can change the channel number to prevent signal confusion. the sender and the receiver units must be set to the same channel number.
Manual flash or stroboscopic flash can be set manually with the receiver unit. Do this in the following cases 1. When you want to set the flash output with the receiver units individually for wireless flash as with studio flash units
It enables you to see the shadow effect on the subject and the lighting balance. You can fire the modeling flash for wireless and normal flash shooting.