Canon EOS R50 Mirrorless Camera (White) - Manual (Page 199)

Note
Can also be set on the [ ISO speed ] screen in [ : ISO speed settings ].
Setting [ : ISO expansion ] to [ Enable ] ( ) expands the maximum speed to H
(equivalent to ISO 51200).
Caution
Image noise (such as graininess, dots of light, or banding), irregular colors, or color
shift may be noticeable at high ISO speeds, in high temperatures, or with long
exposures.
When shooting in conditions that produce an extreme amount of noise, such as a
combination of high ISO speed, high temperature, and long exposure, images may
not be recorded properly.
If you use a high ISO speed and flash to shoot a close subject, overexposure may
result.
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