Canon EOS Rebel T6i EF-S 18-55mm IS STM Lens Kit Instruction Manual - Page 374

Troubleshooting Guide Even though I set a decreased exposure compensation, the image comes out bright.  Set [z2: Auto Lighting Optimizer] to [Disable]. When [Low], [Standard], or [High] is set, even if you set a decreased exposure compensation or flash exposure compensation, the image may come out bright (p.136). When I use the mode with flash, the shutter speed becomes slow.  If you shoot at night when the background is dark, the shutter speed automatically becomes slow (slow-sync shooting) so that both the subject and background are properly exposed. To prevent a slow shutter speed, under [z1: Flash control], set [Flash sync. speed in Av mode] to [1/200-1/60sec. auto] or [1/200 sec. (fixed)] (p.174). The built-in flash rises by itself.  In shooting modes ( ) whose default setting is (Auto flash), the built-in flash will be raised automatically when necessary.  In the and modes, when you press the shutter button halfway under low-light conditions, the built-in flash may be raised automatically and emit the AF-assist beam. The built-in flash does not fire.  If you use the built-in flash too often in too short a period of time, the flash may stop firing for a while to protect the light-emitting unit. 374