Max Shutter speed
Panasonic ZS100 can shoot continuously at max speed of
9.9 fps and has max shutter speed of
1/2000 sec. ZS100 also has an electronic shutter which can shoot silently at max speed of
1/16000s. 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 ZS100 doesn't have an external flash shoe so you are limited with the built-in flash.
One neat feature that we like about ZS100's built-in flash has is that the flash head can be tilted upwards manually using your finger, which can be used to bounce the flash light and create a more pleasing lighting on your subject. It is not a very strong flash so the ceiling/wall or the surface you use for bouncing must be relatively close to the camera.
Focusing
Panasonic ZS100 features a Contrast Detection autofocusing system. The AF system has 49 points to choose from.
Panasonic ZS100 also features
Face detection AF where it intelligently detects the faces in the frame and locks the focus automatically.
Post Focus
Panasonic ZS100 has a special Post Focus mode which uses its 4K video and focus bracketing features together to shoot and stack a burst of images into a single image which you can change the focus point on the LCD screen after it is taken.