Canon EOS 4000D Instruction Manual page 151

If focus is not achieved with the shooting conditions on the preceding

page, set the lens's focus mode switch to <MF> and focus manually.
If you use AF with any of the following lenses, using [Quick mode] is

recommended. Autofocusing with [FlexiZone - Single] or [u Live
mode] may take longer or correct focus may not be achieved.
EF50mm f/1.4 USM, EF50mm f/1.8 II, EF50mm f/2.5 Compact Macro,
EF100mm f/2.8 Macro USM, EF75-300mm f/4-5.6 III,
EF75-300mm f/4-5.6 III USM
For information on other lenses, refer to the Canon website.
If you shoot a peripheral subject and it is slightly out of focus, recompose

to move the subject (and AF point) toward the screen center, focus again
and then take the picture.
The AF-assist beam will not be emitted. However, if an EX-series

Speedlite (sold separately) equipped with an LED light is used, the LED
light will turn on for AF-assist when necessary.
In magnified view, focusing may be difficult due to camera shake. Using

a tripod is recommended.
Using AF to Focus (AF Method)
151