Canon EOS REBEL T7i Instruction Manual page 195

With q (Evaluative metering), the exposure setting will be locked when you
press the shutter button halfway and focus is achieved. In the w (Partial
metering), r (Spot metering), and e (Center-weighted average metering)
modes, the exposure is set at the moment the picture is taken. (Pressing the
shutter button halfway does not lock the exposure.)
e Center-weighted average metering
The metering is averaged for the entire scene
with the screen center weighted more heavily.
This metering mode is for advanced experts.
q Changing the Metering ModeN
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