What are the flash phenomena in photography?

① Diffuse reflection occurs when the light from the light source shines on the athlete, and the athlete forms an inverted and reduced real image through the convex lens in front of the camera.

② According to the characteristics of stroboscopic photography, observe photos and compare the average speed of rackets in AB, BC and CD. BC has the highest speed and AB has the lowest speed. Because the flashing time of the screen is the same, the ball spacing of AB is the smallest, and the ball spacing of BC is the largest.

So the answer is: diffuse reflection; True; BC; AB。