When does Pope Francis have fun?

Most people wait a lifetime for a chance to see the pope up close, but for David Yoder that chance lasted six months. The National Geographic photographer shot 68,000 images of Pope Francis for the book, "Pope Francis and the New Vatican."

In this week's 60 Minutes story on the pope, Yoder gave Scott Pelley a sneak peak at some of his images at the Villa Taverna, the U.S. ambassador to Italy's residence in Rome. They included those where the pope blesses new brides and grooms.

"It seemed to me that that was where he was having the most fun," Pelley told Yoder. The pope seemed "excited about the prospect of new families."

"I think you're right about that," Yoder said. "That's probably his favorite section."

It was also an emotional one. One bride was so overcome upon meeting him that she had to turn away. "She was trembling, " Yoder recalled.

A more surprising photo shows the pope blessing the belly of a pregnant woman -- in a wedding dress. Yoder said it may not be what it seems. "Many of these couples were married even months before," he said.

Yoder also got rare access to the inner workings of the Vatican, places journalists are generally not allowed to go. He revealed that it can be a surprisingly modern place. In one photo, the pope is in St. Peter's Basilica, surrounded by priests taking photos of him on their iPhones.

One of the most striking images is of Pope Francis alone in the Sistine Chapel on Christmas Day, standing under Michelangelo's majestic ceiling. Yoder said it took him months to prepare for that perfect photo, which eventually became the cover of National Geographic's book.

Getting to shadow a pope is an opportunity few will ever have. Yoder said when people hear about his assignment, they often ask a single question.

"They all seem to want to know, 'Is he for real?'" Yoder said. "Obviously I don't know him. But I think he is exactly as he appears to be. "

Photos courtesy of National Geographic Photographer David Yoder.

This Overtime video was produced by Lisa Orlando.