Canon EOS R50 Instruction Manual page 327

Caution
Images may waver or flicker during high-speed display. This occurs more often at
high shutter speeds. However, this does not affect shooting results.
High-speed display is not performed for shutter speeds slower than 1/30 sec.,
aperture values higher than f/11, conditions that make autofocusing difficult, flash
photography, or high ISO expansion. It may also stop as you are shooting.
High-speed display is not available in the following cases.
• With [ : OVF sim. view assist] set to [On]
• With [ : Display simulation] set to [Disable] or [Exposure only during
DOF]
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