Max Shutter speed
Canon R3 can shoot continuously at max speed of
30 fps and has max shutter speed of
1/8000 sec. R3 also has an electronic shutter which can shoot silently at max speed of
1/64000s. One thing to keep in mind is that electronic shutter may cause rolling shutter / jello effects, and also banding issues under artificial light on your images.
Flash
Unfortunately R3 doesn't have a built-in flash but it has a flash shoe for mounting external flashes.
Focusing
Canon R3 features both Contrast Detection and Phase Detection autofocus (AF) systems which ensures speed and accuracy of focusing in most situations. The AF system has 1053 points to choose from. Canon R3 also features
Face detection AF where it intelligently detects the faces in the frame and locks the focus automatically. In addition to the face detect AF, R3 has a more sophisticated feature called
Eye Tracking AF which detects and locks focus to the selected eye of the person in the frame accurately and tracks as the subject moves. Eye tracking AF of Canon R3 is a perfect feature for shooting portraits and is especially useful when fast lenses are used and the depth of field is very narrow.
Focus Stacking
Macro shooters will love Canon R3's Focus Stacking feature. In this mode, R3 automatically composites multiple shots taken at different focal positions using focus bracketing to create a single image with maximum depth of field.