To put things into perspective when it come to Oppenheimer, and Nolan films since The Dark Knight, shooting on IMAX is probably harder and more expensive than a lot of people realize.
I haven't had the pleasure of working on a 70mm movie yet. My biggest format was 35mm anamorphic. Still, I've done a lot of number crunching in preproduction. I know how to come up with solid numbers regarding what people are gonna expect to pay for a format given certain variables.
35mm is generally on par with an ALEXA digital camera if the director knows how to plan out scenes.
Realistically, with IMAX, if you account for buying the film, shipping the film, getting the film processed, getting it transferred for an edit, and so on, you're talking about $10 per second.
So, the opening shot of Cillian Murphy's face in Oppenheimer probably cost a thousandish dollars just on film. That's not even factoring in multiple takes. That's not factoring in the cost of the camera or the lens. That's not factoring in the lighting. That's not factoring in the people.
Much of the film was handheld, even in IMAX. I've handheld a Panavison 35mm camera, and that wasn't fun. IMAX cameras are a lot heavier.
IMAX cameras are also loud. There's a lot of difficulty regarding recording production sound, and looping in post, that have to be accounted for.
Yes, most of Oppenheimer was shot on Super 70mm, which is smaller, cheaper, and easier to work with than IMAX. It's still bigger, more expensive, and harder to work with than 35mm or any digital format.
Still, the published production budget of Oppenheimer stands at $100 million. I've seen reports that it was higher; but, the published production budget of Barbie was almost $50 million more while being shot on video.
Nolan isn't just a master filmmaker, he's efficient as all holy heck.
There's no way that you make a movie like Oppenheimer on large format without pissing off the studio unless you meticulously plan everything.
Filmmakers never have a blank check. Even if they seemingly do for one film, it's usually that film that will kill their careers.
Despite Nolan's consistant success, there's no way that people weren't ready to step in if he started burning through too much film, or going over time.
He had to be a manager. He clearly was.