Robert Downey Jr. Talks Playing 'Iron Man'

With two solo movies and a worldwide smash team-up flick under his belt as the armored Avenger, you’d think Robert Downey Jr. would have the whole being a superhero thing down pat. But even while shooting this summer’s “Iron Man 3,” there was still one part of the process that tested his endurance and his patience.

That would be the claustrophobia.

See, when Tony Stark is inside his armored suit, you don’t see his face behind his mask. So filmmakers invented the HUD (Heads-Up Display) view. That’s when the camera goes inside the suit, so you can see Downey’s face with all of Tony's high-tech graphics floating around him.

It’s a great solution to a sticky problem, and when you’re watching an action scene in the movies you take it as a given that the close-ups you see of Downey are happening at the same time Iron Man zooms through the skies. But that’s not the case. And Downey said creating the illusion is one of the toughest parts of the job. (You read that right: perhaps for the first time ever, an A-list, world-renown movie star feels he has too many close-ups.)

I asked Downey how many days he spent filming the HUD shots during his four films as Iron Man. His sarcastic reply? “Not enough for my tastes.”

When asked if the process--which involves him alone in front of a blank background with a camera in his face--got easier, he said, “No, it didn’t,” and went on to explain why it was so tough for him.

Downey compared it to the process of recording voice-overs for commercials, a job he said he loves, “but you wouldn't know from my disposition every time I have to go in and work, because it's like irritation therapy.” As an actor, Downey thrives on interacting with his costars and being physical, and filming the HUD shots requires him being isolated and immobile.

“When you do the HUD work, usually it's kind of the last thing in the schedule,” Downey said. “And you're going back and essentially living the movie again in close-up, tired.”

Basically, Downey has to relive all of the action scenes in the movie they already shot and deliver the same level of intensity even though he’s standing still and there’s nothing for him to actually react to. That includes performing some of his most emotional scenes, like in “The Avengers” when he is unable to contact Pepper (Gwyneth Paltrow) while he is flying to what he believes will be his death.

Still, Downey did admit that going back to shoot the HUD segments at the end of production gives the team the ability to refine and improve scenes. “We had the luxury of being efficient enough to sometimes say, ‘Stop, stop. Wait a second. Let's not just shoot these next 20 lines. Let's look at the scene and how can we make it a little better or different.’”

Downey did say that it has gotten easier over time to actually wear the physical Iron Man suit. He said the version he wears in the new movie is “lighter; it's more flexible.” Still, he made sure to clarify that “easier” was not the same thing as “easy.” He joked, “There is no comfortable version of it, so it's kind of like, ‘Hey, don’t you think these bamboo shoots are actually a little less rough on the cuticle until they get down to the nerve?’”

You’ll get to see how all of Downey’s hard work and irritation paid off when the final trailer for “Iron Man 3” lands tomorrow, March 5, at noon ET/9 a.m. PT exclusively here on Yahoo! Movies.