It's a Wonderful Life (1946)
But, Capra hadn't expected it, and he had set the camera across the room from Stewart. He was so impressed with Stewart's emotion that he asked him to do it again so he could film it again in close-up. Stewart said no dice, that was the real deal and he couldn't fake it again. So, Capra took the film back to the lab and cropped and enlarged it, and cropped and enlarged it, until he got the "close-up." If you look at the scene closely, you'll see it's grainier than the rest of the scenes. That's because of the enlargement. As usual, Capra got what he wanted (from Shmoop).