'Harry Potter' Cinematographer Recalls Challenges of Transforming Beloved Book Into a Movie

— -- It's hard to imagine that "Harry Potter and the Sorcerer's Stone" first hit U.S. theaters exactly 15 years ago today.

The movie, which grossed nearly $1 billion worldwide, catapulted the careers of its young stars and made "Harry Potter" author J.K. Rowling a household name. Fans were dazzled by the movie's digital effects and in awe of the Great Room in Hogwarts Castle. Moving staircases? Speaking portraits? The technical wizardry that transformed the book into a visual spectacle still draws accolades from moviegoers and Hollywood insiders alike.

John Seale, the Oscar-winning cinematographer who was hired by director Chris Columbus to help bring this magical world to life, told ABC News that there were certainly challenges for the London-based crew. The young actors, many of whom had zero professional experience, were still memorizing their lines in addition to learning the simple mechanics of acting, such as hitting their marks and leaning out of shots.

"The kids were young and very raw to filmmaking," Seale told ABC News by email. "In the early days, they would suddenly falter on their lines, and get a smile as though they were thinking, 'I'm in the Harry Potter movie,' and we would have to do a retake. They were all very intelligent and fast learning kids, so it did not take long for them to become good technical actors."

The crew was busy for months before the actors even set foot on the Leavesden, England, production soundstage, said Seale, who met with his team of electricians over and over again, studying for weeks how to perfectly light the extremely detailed sets. It was a massive undertaking but the cast and crew were up to the challenge, he said.

"Chris kept a wonderfully cheerful set with the actors and crew, so the long days went fast and enjoyably," he explained. "The kids threw themselves into the parts as a great adventure, and loved it, which made it so easy to work with them."

According to the Warner Bros. Studio Tour London website, where fans of "Harry Potter" can purchase tickets to see up close the sets used in the eight films, shooting of the first movie commenced on Sept. 29, 2000. The Great Hall was one of the first sets to be constructed and could seat 400 of the child actors.

Seale fondly remembers one scene that involved the late Alan Rickman, who played Professor Severus Snape. Emma Watson, cast as Hermione Granger, responded so strongly to Rickman's delivery that her reaction was "priceless," according to Seale.

Afterward the shot was filmed, "Emma says, 'That was AWESOME.' Even Alan had to smile," Seale recalled.

Now, 15 years after the movie, "the boy who lived" has become ingrained in our culture, lexicon and even the nation's politics. Long live Harry Potter.