How to fill the light when shooting people at night?

If you shoot people at night, you should slow down the shutter or improve the sensitivity, but it will affect the picture quality.

If you fill the light, you usually use a flash. If you are professional, you should have a soft light cover or a large flash and a soft light cover. If not, put a piece of toilet paper in front of the flash. Can reduce the overexposure of the face.

But if you want to be clear before and after, you'd better slow down the shutter or flash professionally.