The top surface of the Canon EOS Rebel XSi has a few frequently accessed controls of its own. The key controls, shown in Figure 2.11, are as follows:
Mode dial. Rotate this dial to switch among Basic Zone and Creative Zone modes. You’ll find these modes and options described in more detail in Chapter 4.
Sensor focal plane. Precision macro and scientific photography sometimes requires knowing exactly where the focal plane of the sensor is. The symbol on the side of the pentaprism marks that plane.
Flash hot shoe. Slide an electronic flash into this mount when you need a more powerful speedlight. A dedicated flash unit, like those from Canon, can use the multiple contact points shown to communicate exposure, zoom setting, white balance ...