I want photography experts to teach me how to shoot light paintings and clear them up a bit

This kind of light painting photography requires a tripod, small aperture, slow shutter and long exposure. Also try to control the ambient light and make the environment as dark as possible.

So when you say that the light is sometimes unclear, one possibility is that the environment is not dark enough, and the other is that the shutter speed is not slow enough. Use B and try with a longer exposure time.

As for the unclear face, because it is a long exposure, any movement will cause blur, and when people use a flashlight to draw in the air, it is difficult to ensure that the position of the face does not move at all.

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Generally speaking, light painting photography should express your "painting" work, so in most cases the photographer will wear dark clothes and move quickly to try to Make sure there are no people in the photo.

In my personal opinion, there are some contradictions between the clear face and the clear light. To solve it at the same time, you can try to operate it with two people. One person stands there motionless and takes charge of the face photo, and the other People wearing dark clothes draw with flashlights. Give it a try, I haven’t tried it, it’s purely a guess and for reference only, haha.