Canon EOS Rebel T5i 18-55mm IS STM Lens Kit Instruction Manual - Page 328

Troubleshooting Guide ISO 100 cannot be set. Under [54: Custom Functions (C.Fn)], if [3: Highlight tone priority] is set to [1: Enable], ISO 100 cannot be set. If [0: Disable] is set, ISO 100 can be set (p.299). This also applies to movie shooting (p.178). ISO speed [H] (ISO 25600) cannot be set. Under [54: Custom Functions (C.Fn)], if [3: Highlight tone priority] is set to [1: Enable], the [H] ISO speed (25600) cannot be selected even when [2: ISO expansion] is set to [1: On]. If [0: Disable] is set for [3: Highlight tone priority], [H] can be set (p.298). The Auto Lighting Optimizer cannot be set. Under [54: Custom Functions (C.Fn)], if [3: Highlight tone priority] is set to [1: Enable], the Auto Lighting Optimizer cannot be set. If [0: Disable] is set, the Auto Lighting Optimizer can be set (p.299). Even though I set a decreased exposure compensation, the image comes out bright. Set [z2: Auto Lighting Optimizer] to [Disable]. When [Standard/ Low/High] is set, even if you set a decreased exposure compensation or flash exposure compensation, the image may come out bright (p.125). 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 becomes slow automatically (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 [1/200-1/60 sec. auto] or [1/200 sec. (fixed)] (p.219). 328