This mode allows your camera to become a commander, or controller, of up to two banks of an unlimited number of external CLS-compatible Speedlight flash units, with four available channels (figure 4.40D).
In figure 4.40D, screen 2, you’ll see Built-in flash, Group A and B, and a Channel setting. Following Built-in flash and Group A and B, you’ll see Mode and Comp. settings. Use the Multi selector to move around and modify settings on this screen.
Figure 4.40D – Flash cntrl for built-in flash – Commander mode
Built-in flash – This lets you set the pop-up flash to one of three settings. The settings do not affect any of the flash ...