Canon EOS Rebel T6 Instruction Manual page 161

General Movie Shooting Cautions are on pages 181-182.

If necessary, also read General Live View Shooting Cautions on

pages 157-158.
The ISO speed (ISO 100 - ISO 6400), shutter speed, and aperture are

set automatically.
You can press the <A> button (p.120) to lock the exposure (AE lock).

The exposure setting will be displayed for the number of seconds set
with [k2: Metering timer]. After applying AE lock during movie
shooting, you can cancel it by pressing the <S> button. (AE lock setting
is retained until you press the <S> button.)
By holding down the <O> button and turning the <6> dial, you can

set the exposure compensation.
If you shoot a movie with autoexposure, the ISO speed, shutter speed,

and aperture will not be recorded in the movie's Exif information.
With autoexposure movie shooting, the camera will automatically turn on

the Speedlite's LED light under low-light conditions. For details, refer to
the Speedlite's instruction manual.
k Shooting Movies
161