9 Ways to Customize Your Canon Rebel t5i
Disable the AF-assist beam.
In dim lighting, your camera may emit an AF-assist beam from the built-in flash when you press the shutter button halfway — assuming that the flash unit is open, of course. This pulse of light helps the camera see its target better, improving the performance of the autofocusing system.
If you’re shooting in a situation where the AF-assist beam may be distracting, you can disable it in the P, TV, Av, or M exposure modes. Make the change via Custom Function 4.