Canon EOS 250D Advanced User's Manual page 262

Adjusting the LCD Monitor Brightness
You can adjust the brightness of the LCD monitor to make it easier to view.
Under the [5] tab, select [Disp.
brightness], then press <0>. Press the
<Y> <Z> keys to adjust the brightness on
the adjustment screen, then press <0>.
When checking the exposure of an image,
set the LCD monitor brightness to 4 and
prevent the ambient light from affecting the
image.
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