Canon EOS 250D Advanced User's Manual page 185

You can display the histogram by pressing the <B> button. However, the
z
histogram is not displayed while pressing the shutter button completely.
When <g> is displayed in white, it indicates that the Live View image is
z
displayed at the brightness level closely matching that of the actual image to
be captured.
If <g> is blinking, it indicates that the Live View image is displayed at
z
a brightness that differs from the actual shooting result because of low- or
bright-light conditions. However, the actual image recorded will reflect the
exposure setting. Note that the noise may be more noticeable than the actual
image recorded.
Exposure simulation is not performed in <8: FG> modes, when Multi
z
Shot Noise Reduction is set, when flash is used, or when bulb exposure is
used. The <g> icon and histogram will be displayed in gray. The image is
displayed on the LCD monitor with standard brightness. Also, the histogram
may not be properly displayed in low- or bright-light conditions.
The <g> icon will also be displayed in gray in the <v: ABCD>
z
modes. The histogram will not be displayed.
Warnings:
Do not hold the camera in the same position for long periods of time.
Even if the camera does not feel too hot, prolonged contact with the same body part
may cause skin redness or blistering due to low-temperature contact burns. Using a
tripod is recommended when using the camera in very hot places or for people with
circulation problems or poor skin sensation.
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