Harry Potter Used An Extremely Old-School Trick For The Time-Turner's VFX
"Prisoner of Azkaban" is easily the best movie in the "Harry Potter" franchise. Part of that's due to how it's adapting the best book from the source material, but it's also due to how high-effort it is. Director Alfonso Cuarón, who almost didn't even make this movie, is always going the extra mile with the way he chooses to frame a scene, and you can see that clearly when we get to watch Hermione's Time-Turner in action.
When Hermione spins the Time-Turner, a lesser director would've done a close-up on Harry and Hermione as the light changes around them. But Cuarón chose to move the camera backwards through time — not just showing the lights moving through the windows, but three hours' worth of magical tomfoolery taking place in the infirmary room where Harry and Hermione are standing. The quick glimpses of patients going in and out of the room also include a student who appears to have accidentally turned himself into a mummy; the movie never explains what happened there, and it's all the better for it.
For effects supervisor Roger Guyett, this is one of the most difficult movie scenes he's ever worked on. "The shot, designed in part by our cinematographer Michael Seresin, required a tremendous amount of planning, because the sun was moving at a different rate in the foreground and the background," he told Vulture in a 2019 feature. "We had the original camera moving with the main characters, and to get everyone speeding up in the background, we had to shoot multiples passes with a motion-control rig. In all the activity happening behind them, we can get everything moving as fast as we like, even though both sets of actors are moving in normal time."
The Time-Turner scene was harder to make than it looks
"It sounds relatively trivial until you actually figure out how to do it," Guyett continued. "So we ended up using plenty of miniatures — miniature clock tower, miniature grounds — really relying on graphics and planning. It's a multi-element shot stitched together with digital technology, but mostly, it depends on old ideas."
The goal was to realize Cuarón's vision of a scene that truly "capture[s] the spirit of seeing time reversing itself, circling around you," and it's hard to argue with the results. It's easy to understand the gist of how the trick's being done on second watch — essentially, Harry and Hermione are being filmed in one take, everyone else is being filmed in another take, then that second take is reversed and combined with the first one — but that doesn't take away from the magic of the finished scene. The fact that they're putting all this effort into such a short scene, combined with how the camera never stays still at any point throughout it, really helps to underline just how much the people involved truly cared.
"Prisoner of Azkaban" is filled with shots like these, including multiple moments where the camera seems to pass through mirrors, that feel almost like the movie is casually showing off. "I'm doing something this cool just on a whim," Cuarón seems to be telling us with, among other moments, that early two-minute long take in the Leaky Cauldron. "Just wait for what else we've got in store."