The flash is a momentary light source, so it can solidify moving objects. Some students don't seem to understand why it can solidify, but it is actually very simple. Suppose you are in a dark room. At this time, someone was jumping up, and the flash came out just in time. Then the flash fires the moment, the camera catches the light, and the exposure is made. But the character is still moving, won't the movement of the character form a blurred image in the picture? No, because the person has not had time to move, before he has moved in the air, the flash light ends, and the room is dark again. The camera couldn't expose, and couldn't see the movement track behind him. It can be used to replace the effect of freezing things with a high-speed shutter, provided that it is a dark room.

Constant light, some people call it a fill light, some call it a video light, some call it a constant light, maybe as time goes by, a more standard name will appear in the future to unify these lights, so now Let's call it a constant light for now. Because flashing describes a state of light, and constant light describes a state of light.