I’ve often been asked to share the most surprising thing I’ve learned about Woody Allen after spending two years making “Woody Allen: A Documentary.” My stock answer can be distilled to this: “He’s a fake.”

What I mean is that the public persona we’ve come to know as the “Woody Allen character” is just that — a character. The three N’s so often used to describe the public Allen are nebbishy, nervous and neurotic. But the contrast between the Woody character and the “real” Allen is never more in focus than when he’s on the set, directing.

Because any director must have the confidence to think on his or her feet and answer about 20 questions every minute, it’s hard to imagine that anyone as anxious as “classic” Allen would survive in the midst of all that chaos. But the “real” Allen does more than survive. He displays a remarkable sense of calm when at work, a confidence and security that are the antithesis of his public image, and both the crew and the actors take their cues from him.

Every actor I spoke to on the London set of “You Will Meet a Tall Dark Stranger,” and every actor I interviewed who’s worked with Allen over the years, from Diane Keaton to Owen Wilson (and dozens in between), all speak of Allen as a low-key, unflappable director. A veteran cinematographer once told me the only directors he knew who got exactly what they wanted acted like fascists on the set and ran over anybody who got in their way. Allen proves him wrong.

Since histrionics are the last thing you’ll find on Allen’s set, he even questioned whether it was worth my while to film him at work. “My sets are boring,” he warned me. “Nothing exciting ever happens, and I barely talk to the actors.”

Yet some sort of alchemy does take place, because, more often than not, the end result with Allen’s films can be quite remarkable. (At the age of 76, he finds himself the recipient of four more Oscar nominations for his most recent release, “Midnight in Paris” — an accolade that seems to impress everyone but Allen.) For a guy who “barely talks to the actors,” Allen seems to repeatedly bring out their best. Under his tutelage, those actors have been nominated for 16 Academy Awards and have brought home the coveted statuettes six times.

So what’s his secret? As the saying goes, it’s complicated.

The comfort level that actors find on an Allen film might play a role. Josh Brolin refers to the set as “very blue-collar,” meaning it lacks the self-importance, the preciousness of many movie sets run by less accomplished directors. For instance, Allen does not retreat to his trailer while the crew is setting up the next shot. In fact, he has no trailer, which tends to diffuse any complaints an actor may have about his or her own accommodations. Between takes, Allen remains accessible to cast and crew as he sits in any nearby chair, talks to his assistant or his producer (who is also his sister), reads the paper or practices his clarinet until he’s needed again. “It’s a great loafer’s job,” he confessed to me. “Much less stressful than if I were running around delivering chicken sandwiches in a deli somewhere.”

It also helps that the hours are reasonable, and the actors aren’t overtaxed. Allen works mainly in single master shots and doesn’t bother shooting coverage from numerous angles. This alleviates the need for actors to do the same scene over and over again just so that the editor will have different shots to use within the scene. So what appears to be a stylistic choice — a minimalist aesthetic — is actually just Allen’s way of staying on schedule by eliminating a lot of repeated takes. In his usual self-deprecating manner, he claims he simply doesn’t have the patience to seek absolute perfection. Once he gets a good take, he wants to move on, wrap at a decent hour and get to the Knicks game in time for the tipoff.

This is not to say that actors who go to work for Allen are pampered. Far from it. His actors receive no more than the guild-mandated minimum payment for their services. There are no inflated star salaries and no perks — not even a second airline ticket for spouses, let alone for an entourage. If you prefer to live high on the hog while on location on an Allen picture, you could literally lose money. And some do! Yet countless actors of the highest caliber wait for that call from Allen’s casting office saying the director is interested in them for a role.

Why do so many actors want to work with Allen? It may have something to do with his Zen-like ability to direct by not directing.

Sean Penn tells me: “He didn’t ask to see or know anything [about my character] until he rolled the camera. His feeling is that the best, complete thing he’s going to get is going to come out of the actor’s instinct. And what he finds out on day one is whether or not he cast it well.”

The conventional wisdom about “serious” actors is that they want to dissect their character with their director, discussing everything from the character’s back story to what he or she had for breakfast that morning. Allen engages in none of this “nonsense” (his word). His theory, rather, is to “hire the best actors, shut up and get out of their way.”

The actors eat it up. Many of the performers I interviewed spoke of the sense of liberation they feel when a director is confident in their ability to come up with the goods without micro­managing their performance. Says Martin Landau: “We never discussed the character. I never heard anyone complain about it because I think it allows a good actor a kind of freedom: ‘Here’s a canvas. Paint!’ ”

Allen may be uninterested in babbling on about his “process,” but he’s definitely going after a specific result, whether or not his actors realize it. Naomi Watts seems to have caught on to his subtle sleight of hand. She refers to Allen as “the best actor’s director I’ve ever worked with,” but concludes, “There’s not as much free rein as we’re led to believe, because he has a sense of how the scene’s going to work and we need to move within those parameters.” Still, she realizes that “he wants to empower us to find it . . . and he’ll do it in such a gentle fashion that we don’t even understand it’s being done.”

Larry David is more to the point: “This notion I hear that he doesn’t direct, I mean, that’s kind of ridiculous. He gets what he wants.”

It’s not unusual for genuinely modest artists to oversimplify the creative process that led to their success. Allen is no exception. “It’s not rocket science,” he said. “This is not quantum physics. If you’re the writer of the story, you know what you want the audience to see because you’ve written it. It’s just common sense. It’s just storytelling, and you tell it.”

So much for Allen revealing the bag of tricks that has led him to become one of the most heralded auteurs of the past four decades. Finding him more at ease discussing practical matters, I pressed him on one that I was especially curious about: Why is he so willing to eschew his right to that private trailer on the set — something few directors are willing to live without?

On this point, he was more open.

“I don’t like the bathrooms in those trailers,” he told me. “I don’t know where that water comes from.”

Sometimes, the Woody character and the real Woody are indistinguishable.

Weide was the executive producer and principal director of HBO’s “Curb Your Enthusiasm.” His most recent film, “Woody Allen: A Documentary,” has been released on DVD. Twitter: @BobWeide.