LOS ANGELES — “What do we do? What do we do? What do we do?”

Michael Bay was whispering these words to himself, mantra style, and biting his fingers as he perched at his computer like a bird of prey. On the second floor of his office in Santa Monica, he was holding a videoconference with artists at Industrial Light and Magic, the special-effects company, and something was bothering him.

As Mr. Bay watched ILM’s preliminary animation for his latest “Transformers” movie, blocky images of giant robots trading blows in the middle of a city, his visceral reactions, often with variations on the word “cool” — “That’s pretty cool”; “We can do something cooler”; “Maybe you could get a nice slice through his face” — seemed to signal approval.

But he was dismayed by footage from “The Last Ship,” a television pilot he is producing, deeming a scene of two men leaping simultaneously from a moving helicopter to be “lifeless” and “a complete fake.”

Striving to be diplomatic, at least with a reporter in earshot, Mr. Bay told the artists: “I would rip every one of these shots apart, right, guys? But these are my friends.”

These are the kinds of images — aggressive, explosive and relentless — that Mr. Bay, the 48-year-old director and producer, sees all the time on movie screens, monitors and sometimes in his sleep. Even when he isn’t fully articulating his expectations, he knows when what he sees deviates from the film he imagines.

“I don’t always know what I’m doing,” said Mr. Bay, a tall, lean man who speaks in a smooth growl, “but you’ve got to jump off the cliff with me and just hope.”

In his latest film, “Pain & Gain” — for which, Mr. Bay said assuredly, “I had a pretty good idea in my head” — it is tempting to see a quick and inexpensive response to the excess that his films are known for. It is a project all the more surprising for the fact that its director doesn’t quite see it in these same terms.

“I wanted to do a quirky movie,” he said. “I wanted to do something small, just actors acting. It was almost like film school again for me.”

For nearly a decade, Mr. Bay contemplated a dark comic caper based on the real-life exploits of Miami bodybuilders who fumbled their way through extortions, kidnappings and murders. On a rare break between “Transformers” movies, he finally made that film, which stars Mark Wahlberg and Dwayne Johnson and which Paramount will release on April 26.

Mr. Bay could boast that “Pain & Gain” was shot in 42 days, that it cost about $26 million (compared with $195 million for the last “Transformers”) or that it features only one scene of a car blowing up. But he prefers to emphasize its message. “It says a lot about life in a weird way,” he explained. “People just don’t appreciate what they have.”

In his career, Mr. Bay has had plenty to work with. Through action films like “Bad Boys” and “The Rock,” his man-versus-asteroid thriller “Armageddon” and three installments of “Transformers,” based on the Hasbro toys, he has become synonymous with the bigness of Hollywood movies: big budgets, big box-office returns, and big, big differences of opinion about whether they’re any good. To the extent that Mr. Bay acknowledges his own reviews, he says he is not striving for any artistic credibility he has somehow been denied. But he recognizes that sheer bigness becomes confining — an obstacle to making movies as rapidly as he wishes.

“When they get too big, it becomes un-fun,” he said. “You just see the money leaking away.”

But when you are Michael Bay, what does it mean to work small?

There is not much modesty to the Bay Films office, housed in a brick building that was once an auto-body shop that Mr. Bay, a Southern California native, frequented as a young man. Today it teems with artifacts from his “Transformers” films, which have sold nearly $2.7 billion in tickets worldwide, and replicas of villains like Jason Voorhees and Freddy Krueger from the “Friday the 13th” and “Nightmare on Elm Street” horror remakes produced by his Platinum Dunes company.

Mr. Bay himself was trickier to locate as he bounced between meetings about a new “Teenage Mutant Ninja Turtles” movie he is producing, and a fourth “Transformers” movie whose start date was weeks away.

“That’s when you want to blow your brains out,” he said, “because you’re thinking, ‘Oh my God, so much pressure.’ ”

But on some level Mr. Bay enjoys being frenetically busy and working under adverse conditions. In his favorite anecdotes, he is the underdog who pushes back against those who thought they knew better — whether it’s Will Smith, who he says didn’t want to bare his chest in “Bad Boys,” or Jeffrey Katzenberg, who he says didn’t find the movie humorous at first — and who then prevails.

On the first “Transformers,” Mr. Bay said, he was chided by Steven Spielberg for allowing actors to improvise too much.

“Steven said to me, ‘Michael, I would like you to shoot something that’s in the script,’ ” he recalled. “And I was like, ‘Steven, this is how I work.’ ” Even if 80 percent of what he shot was terrible, Mr. Bay said, “You’re going to get 20 percent that’s gold.”

Since then, Mr. Bay said, Mr. Spielberg has come to see things his way. “Steven’s like: ‘You’ve got to have the funny. That’s part of the brand of ‘Transformers.’ ” (A spokesman for Mr. Spielberg confirmed Mr. Bay’s account of events.)

While success has reinforced Mr. Bay’s confidence, those who have known him over the years suggest that a certain directorial flair and a determination to prove himself have always been there.

The “Avengers” director Joss Whedon, who was a classmate of Mr. Bay’s at Wesleyan University in the 1980s, remembered him as being “very sweet” and for making a student film in which Mr. Bay’s car, a yellow Porsche, featured prominently. “It was way better than mine,” Mr. Whedon said of the film. “I don’t mind making fun of his because I burned the negative of mine.”

The producer Jerry Bruckheimer, who helped pluck Mr. Bay from the slush pile of commercial and music video directors to take on “Bad Boys,” said that while the director’s style, with its hyperkinetic movement and untraditional camera angles, can seem baffling in its component parts, he never loses sight of his end product.

“When a studio sees his dailies, it scares them,” said Mr. Bruckheimer, who also produced “Armageddon” and “The Rock.” “They look at dailies from a more conventional director, and think when they hire Michael they’re going to get something similar, and they’re not.

“Some people don’t realize that he’s got this vision, and will fight against that. He’s been proven right just about every time.”

Having waged these battles often enough, Mr. Bay all but expects to be misunderstood, and to be vindicated. But not always: He took a critical beating for his 2001 war drama “Pearl Harbor,” a film he maintains was a financial success but on which he said he was hampered by requirements to release it with a PG-13 rating. “I would have made it a little harder,” he said. “There wouldn’t have been as much love story.”

And he has been derided by his actors, like the “Transformers” co-star Megan Fox, who said in a 2009 interview that Mr. Bay was “a nightmare to work for,” adding, “He wants to be like Hitler on his sets, and he is.”

Mr. Bay said Ms. Fox had since apologized to him. “I have no ill will for her,” he said. “I knew she was young back then. It’s hard when you’re famous at that age.” (Ms. Fox, who is starring in his new “Ninja Turtles” film, did not respond to requests for comment.)

There is also the baseline level of scorn that greets Mr. Bay’s new releases, delivered with a hostility usually reserved for corrupt politicians or industrial polluters. For a not-at-all-random sampling, consult Roger Ebert’s takedown of the 2009 “Transformers” sequel “Revenge of the Fallen,” which he called “a horrible experience of unbearable length, briefly punctuated by three or four amusing moments.”

“Faust made a better deal” than Mr. Bay did, he added.

Mr. Bay dismissed such criticism as “boring” and defended himself at some length as being an easy target because he is one of a few directors who is known by name around the world.

“Listen,” he said, “I was just in the Forbidden City, and people were taking pictures of me. People know who you are, so maybe that gives more license for, ‘Oh, I know that guy, I’m going to attack him.’ But it’s actually really tiresome.”

Mr. Bay said that “Pain & Gain” had gotten him excited in the right way, connecting him to the energy and the pastel-colored palette of Miami Beach, where he has lived in recent years, and allowing him to get “down to the down and dirty.”

Mr. Johnson, who plays an inept and drug-addled ex-con in the film, said, “There was a point where I was reticent about playing the role, because of the dark turns it was taking, and trying to find my clarity.” But when he wavered, he said, Mr. Bay surprised him by writing him a long letter that restored his confidence in the project.

“The overall message was: ‘You were born to play this part. And now, I need you to trust me,’ ” Mr. Johnson said. “I was so blown away at the time.”

The lesson he learned about Mr. Bay, he said, was that “behind the intensity and, oftentimes, the complications of getting” things (Mr. Johnson used a different word) “done in an efficient way is a very insightful guy.”

Mr. Wahlberg, who plays the musclebound ringleader Daniel Lugo, praised Mr. Bay for his versatility, for being “great with humor and action, and suspense and drama.”

“You get the artsy-fartsy guys of the world who do these little quirky comedies or dramas, that think they’re cool and they’re the artists,” said Mr. Wahlberg, who has also worked with Paul Thomas Anderson and David O. Russell. “But he can do the stuff that other guys can’t do.”

When, at the end of “Pain & Gain,” Mr. Bay offered him a lead role in the next series of “Transformers” movies, Mr. Wahlberg said he accepted without hesitation.

“He said, ‘Well, let me tell you about the part and the story,’ ” Mr. Wahlberg recalled. “I said, ‘Dude, if you want to. Or you could just tell me where to stand and what to say.’ ”

Now that he has done “Pain & Gain,” Mr. Bay is hardly contemplating a transition into independent cinema. He is producing his movies and television pilots and feels a special attachment to “Transformers,” in part because it keeps him in an exclusive club of directors who are associated with continuing film franchises.

“Jim” (Cameron, of course) “is doing ‘Avatar,’ and Peter” (Jackson, naturally) “has been in Middle-earth for a long time,” Mr. Bay said. “I don’t know how many I’m going to do, but I’ve got to set this franchise up again for somebody.”

Then there is the Mr. Bay who just likes to hike and play softball, watches “Homeland” and considers himself a frustrated landscaper, and wonders if he could walk away from the apparatus he has built himself, if only temporarily.

“I want to chill out for a little bit,” after the next “Transformers,” he said hesitantly. “I think. Smell the flowers a little bit.”

With some wistfulness, he added: “I wish I would read more. I used to be a huge reader. It’s just — life gets too busy.”