Max Shutter speed
Nikon D850 can shoot continuously at max speed of
7.0 fps and has max shutter speed of
1/8000 sec. If you need more speed, Nikon D850 can shoot up to
9 fps with optional battery grip.
Flash
Unfortunately D850 doesn't have a built-in flash but it has a flash shoe for mounting external flashes.
Focusing
Nikon D850 features both Contrast Detection and Phase Detection autofocus (AF) systems which ensures speed and accuracy of focusing in most situations. The AF system has 153 focus points and 99 of these sensors are of Cross-type. Cross-type sensors locks focus faster and more accurate compared to single type sensors. Nikon D850 also features
Face detection AF where it intelligently detects the faces in the frame and locks the focus automatically.
Focus Stacking
Macro shooters will love Nikon D850's Focus Stacking feature. In this mode, D850 automatically composites multiple shots taken at different focal positions using focus bracketing to create a single image with maximum depth of field.