Look at the light, first of all, it should be bright enough, use the shutter as fast as possible to see what effect you want, and if you want to jump rope, freeze it in the picture as soon as possible. If you want to pursue motion blur, the speed should be1100, which is almost enough. If you slow down, people will be blurred. . If the light is not enough and the aperture is not big enough, use a flash. The flash synchronization of 400D is 1/200. That's enough. Adjust the flash compensation to the maximum. Adjust the aperture appropriately You can almost shoot the skipping rope and freeze it in the picture 1/200 seconds. .