Our recent post on Social Media debunks the "moving background" illusion that has been going viral in China. The trend exploded after a video surfaced on Douyin (China’s version of TikTok) showing influencers dancing on a hilltop while the background shifts in a dramatic, vertical motion. Scanning from top to bottom, the camera technique creates a completely unique perspective.

Let’s dive in.

Recreating this effect comes down to two key factors: using a telephoto lens and locking onto a subject while moving the camera straight up. Traditionally, this high production look required expensive film gear like cranes, dollies or even helicopters. Today, consumer aircraft like the DJI Mavic or Air series can pull off the exact same task at a fraction of the cost.

The Science of Lens Compression

Take the Mavic 4, for example, which features a built in 168mm telephoto lens. This specific focal length drastically narrows your field of view. Think of a narrow field of view like looking through a long paper towel tube. Because you are looking through such a tight space, you are forced to take several steps back just to fit your subject into the frame.

While backing up makes your foreground subject look smaller, it has almost zero effect on your physical distance to a mountain that is already miles away. The telephoto lens then acts like a magnifying glass, filling up that tiny circle of view to fill the entire picture. This scales up the mountain while keeping the subject a normal size, making the background look like it is a lot closer than it actually is.

Try It on Your Phone

If you want to test this out for yourself, grab your phone and open the camera. What you see on your mobile screen typically sits around a wide 22mm lens, depending on your device's brand and model.

Line up a shot of an object close to you with a deep background behind it. Ideally a car with some houses in the distance. Now, zoom in completely and tap to focus on the car. You will immediately notice a distinct optical squeezing taking place where the background appears much closer. This effect is known as lens compression.

Activating the Parallax

If you were to slowly move your camera upward while keeping the car locked dead center in your frame, you would see a vertical parallax effect unfold right before your eyes. In essence, this is exactly what the drone is doing, just on a much grander scale. Once you couple this flight path with a bit of post production cropping, reframing and stabilization smoothing, the moving background effect is complete.