TORONTO - Just like many of the series' passionate fans, "Harry Potter" star Matthew Lewis says he fretted when he heard that the blockbuster franchise's final instalment would be presented in 3D.

But now that he's seen the breathlessly anticipated "Harry Potter and the Deathly Hallows: Part 2," he wants to assure his fellow Potter-philes that the effects are a welcome addition.

"I'll be honest, I was very, very worried about this 3D conversion," the affable Lewis said during a roundtable interview in Toronto on Tuesday. "Some of the (3D) films I saw -- (which) I won't name -- weren't good.

"But I thought, if (director) David Yates and (producers) David Heyman and David Barron believe that this will better the film and it will not detract from the story, then I trust them implicitly because the story means so much to those three, so much. And there's no way they'd ever let it go ahead for monetary gain, they'd do it because it was going to help.

"And so, with that in mind, I went in there to see it and after the first scene, I completely forgot I was wearing 3D glasses. And the only moment I remembered was when I had to wipe the tears from my eyes for Alan Rickman's performance, he was splendid."

Of course, it's likely many other Potter devotees will fall into a similarly sentimental state when the eighth and final film in the film franchise opens on Friday.

Plenty of ordinary "Muggles" spent a sweltering day in Toronto gathered outside the Scotiabank Theatre, hoping to catch a glimpse of some of the film's talent en route to a screening, which was to be followed by a party at historic Casa Loma.

The final entry in the saga -- based on J.K. Rowling's mega-successful series of enchanting young adult novels about a school of wizardry and a small orphan with a crucial destiny -- wrapped last year, an experience that series stars Daniel Radcliffe, Emma Watson and Rupert Grint have uniformly described as being fraught with sadness and nostalgia.

But Lewis, who has been featured in every "Potter" film, says he wasn't afflicted with such melancholy -- at least not right away.

"I finished the filming, and I never felt this emotion that everyone else was talking about. I didn't really get it," said the 22-year-old Brit. "It was sad, but I never really felt like crying or anything like that.

"And then when we got to the premiere in London just last week, and I looked out at this sea of people, and I realized this was our last time we were going to be presenting our film to these fans ... and I remembered what it was I'd be missing."

The rest of the screening, however? That was a "blur." In fact, Lewis says his nerves gnawed away at him as he watched the final "Potter" chapter, and he wanted it to be over as quickly as possible.

See, his beloved character, Neville Longbottom, began the series as a sweetly harmless, chubby-cheeked nebbish, someone who was a victim of mean-spirited pranks and who burst into tears when he lost track of his pet toad. By the end, he's become a courageous -- and, as Lewis puts it, "crucial" -- warrior in the battle against evil Lord Voldemort.

And Lewis, who was 12 when the first movie was released, says nailing that transition was important to him.

"This is the one that I really wanted to get right," says Lewis, clad in a golf shirt, cardigan and jeans.

"The moments that Neville has in this film were kind of crucial. I knew as a fan how important they were and I wanted to make sure we really nailed them, so to hear the critical responses -- it's lovely and it's very overwhelming.

"I don't hear nice things often, so it's very good."

Well, Lewis might not have been paying attention lately.

While the actor used to have to don a fat suit and false teeth to portray his gawkish character, plenty of commentators have noticed the way he's matured as he's grown up onscreen.

Radar Online recently ran a story on Lewis with the headline "From Dud to Stud," while New York Magazine asked its online readers: "Where were you when you realized Neville Longbottom has gotten really hot?"

"I'm very uncomfortable with all that, to be honest," he blushes, shifting his gaze down toward the table.

"Everyone's very, very nice, it's lovely, it's very kind. But I'm very awkward with it. It's not something again that I'm used to."