There is a kind of photo that I saw in the movie. You can take photos with a flashlight and stick the images in the photos on the wall. What is black technology?

Do you believe that movies are fabricated and against science? The light of the flashlight shines on the photo, and the paper base of the photo paper is very thick. The light of the flashlight is not a good point light source, but a messy spotlight. After passing through the photo, the light is weak and scattered, and it is impossible to image on the wall at all. If there is a convex lens on the other side of the flashlight, adjust the lens and photos, and the distance between walls is appropriate, so you can image on the wall. Is this lens in the focal plane? No, it's just that the director doesn't understand science.