Canon PowerShot G7 X Mark III Advanced User's Manual page 101

To focus more accurately, try attaching the camera to a tripod to stabilize it.
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You can start manual focus with magnified display (MF-point zoom).
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Press the shutter button halfway to have the camera fine-tune the focal
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position (Safety MF).
Magnified display in step 2 is not available during RAW burst shooting.
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