'Harry Potter' director on first film with Daniel Radcliffe, Rupert Grint, Emma Watson: 'I couldn’t get them to stop smiling'

Daniel Radcliffe, Rupert Grint and Emma Watson were giddy children when they debuted as Harry Potter, Ron Weasley and Hermoine Granger, respectively, in 2001's "Harry Potter and the Sorcerer's Stone."

So, they reacted like giddy children.

"In the first film, there was not a lot of professional experience between the three leads," director Chris Columbus told Variety. "That's why that film was filled with so many cuts. I could only really shoot, for the first three months, a close up of one of the actors before they would lose concentration. The first couple of weeks, all the kids were so excited to be part of the 'Harry Potter' film, they were basically just smiling into the cameras. I couldn’t get them to stop smiling, and it really became an exercise and acting class for me as a director."

The one-time Oscar nominee continued: "By the time we got to the second film, we were able to do tracking shots and the kids could shoot a master and have a conversation within those shots. They became very professional by the time they got to 'Chamber of Secrets,' and then by the time we did 'Prisoner of Azkaban,' you could basically shoot the entire film in 15 single takes if you wanted."

Columbus directed and served as executive producer for the first two Harry Potter films ("Sorcerer's Stone," "Chamber of Secrets") and was credited as a producer on the third ("Prisoner of Azkaban").

Radcliffe, Grint and Watson starred in all eight installments of the iconic, world-beating franchise — the seventh, "The Deathly Hallows," was split into two parts — from 2001 to '11. Of course, the films were adapted from J.K. Rowling's bestselling novels.

The 20th anniversary of "Sorcerer's Stone" will be celebrated with a theatrical release on Nov. 14.