Filmmaker Chris Columbus' name has been synonymous with several great films over the years, whether for his turns as a writer ("Gremlins" and "The Goonies") or a director ("Home Alone") working off of somebody else's original script.

But with "Percy Jackson & the Olympians: The Lightning Thief," Columbus returns to the helm of a big-screen adaptation of a blockbuster novel, a entirely different animal made up of a vocal fan base that he first encountered nine years ago directing "Harry Potter and the Sorcerer's Stone." While the film ultimately was a triumph, Columbus said he had to make it with an decidedly different mindset.

"When we were doing the first 'Potter' film, we felt like we had the eyes of the world looking over our shoulders," Columbus recalled in a recent @ The Movies interview. "People were asking, 'Who are you going to cast and are you going to remain faithful to the source material?' From a directorial standpoint, I felt a bit bound in the sense of creative freedom. I couldn't really think about the film first. I had to think about being faithful to the book and making the film."

Fortunately for the filmmaker, he was allowed a lot more breathing room with "Percy Jackson" -- something that he could never have dreamed of as the director of "The Sorcerer's Stone" and "Harry Potter and the Chamber of Secrets" -- as well as producer of "Harry Potter and the Prisoner of Azkaban."

"I realized that when I got into 'Percy Jackson,' I was going to think of the film first," Columbus said. "I was going to think of the best possible version of the film and the most exciting thrill ride for the audience. And if that meant that we had to replace certain scenes in the book with other things that were more cinematically more visceral, I did that."

"As a result, the book is a wonderful book, and the film works on its own as well," Columbus added. "I showed the film to a bunch of kids who are fans of the book and they said, 'Well, it's a little different than the book -- but we love the book and we love the film.'"

Without question, the most noticeable change in "Percy Jackson" comes with the age of the title character, who has turned from a 12-year-old boy on the pages into a 17-year-old (Logan Lerman) on screen. Columbus said the decision to age-up Percy Jackson -- a trouble-prone teen who discovers he's the son of a Greek god in the midst of a brewing battle between his ancestors – was done in an effort to ground the character in more realism.

"When it comes to a character of Percy, I think of a kid who's dealing with issues of parental abandonment, dyslexia and ADHD, and yet he and his fellow demigods have to train in battle scenarios where they are fighting for their lives against the dark forces," Columbus observed. "I realized that with the type of sequences I wanted to tell in the film, there wasn't a 12-year-old capable of handling that sort of intensity and that sort of training."

Plus, Columbus had the "Potter" factor to consider: After all, Percy Jackson is accompanied in his quest by two other protagonists -- Annabeth (Alexandra Daddario) and Grover (Brandon T. Jackson) – and a younger trio just might have felt strikingly familiar to fans of Harry, Ron and Hermoine.

"I certainly feel there are similarities in the source material, so I was sort of the perfect guy to direct this movie because I removed as much of any similarities that I felt were there," Columbus said.

Still, the director added, there are certain themes within the fantasy film genre that just can't be denied when trying to tell a story like "Percy Jackson."

"There's a similarity between all fantasy films," Columbus said. "The good fantasy films stem from, in a sense, the essence of Greek mythology, which is what (author) Joseph Campbell was always talking about. Whether it's 'Star Wars' or 'Spider-Man' or any of those types of films, you've got a main character that is flawed in some sense, and is looking to fill some sort of emptiness within themselves. It's about something they've lost and they have to go on a quest to go and find."

The funny thing is, Columbus added, he's already been down the trio of young heroes route -- and long before "Harry Potter" and "Percy Jackson" took flight.

"I wrote the movie 'Young Sherlock Holmes' back in 1985, which you could say is similar to 'Harry Potter.' There are three young protagonists -- two of them boys and one a girl -- and they go on a fantasy adventure in London. If you want to look at fantasy films, you can find all kinds of comparisons. I guess it doesn't help, though, that the studio sells 'Percy Jackson' as a film from the director of 'Harry Potter,'" Columbus said, laughing.

Common theme notwithstanding, Columbus said there are a lot of fresh things to pick from "Percy Jackson."

"The originality of the concept is what really made me want to do the movie," Columbus said. "This idea of Greek mythology, and these wonderful creatures, gods and stories all existing in contemporary America, was exciting."