The harder you look at some things, the faster they fall apart. Blow-Up is about a photographer, a jaded and blasé fellow surrounded by people as jaded and blasé as he, who finds one thing in his life worth looking at. And he stares at it, and stares at it, until it and everything else around him disintegrates. His world was never meant to hold up to that kind of scrutiny.
We have no idea at first what Thomas (David Hemmings), the protagonist of Blow-Up, is up to. He emerges, bleary and unshaven and in wrinkled clothes, from a flop-house, trailed by dozens of other tramps. Then he rounds a corner, does a double-take to make sure no one's looking, climbs into a convertible Rolls-Royce, and drives off. This is in fact his car; he's a hot young photographer who spent the night sleeping with the homeless to surreptitiously snap photos for a book project. He arrives at his studio, still unkempt, for a morning shoot with a model (Verushka). In his eyes, it's her problem if she had to wait, or if she's bothered by his ratty condition. Same with the girls he shoots later for a fashion splash, whom he grouses at and orders about like they're undisciplined kids on a picnic. Same with the models who cold-call him at his office, and whom he cold-shoulders in return.
Not the nicest guy. "I'm fed up with those bloody bitches," he grouses to his publisher. He's got money, just not "tons of money". A gay couple walking their dogs inspires a sneer. But he's interesting to watch, and not just because he moves and shakes with other movers and shakers. We see some of his work, and he's clearly talented. He's also hungry for images outside of the day-job part of his life, and so he takes his camera for a walk in the park. When he spots a couple, a woman (Vanessa Redgrave) and an older man, frolicking in an isolated area, he's elated — literally clicking his heels with joy — and snaps away. Then the woman corners him, livid, and demands the film, even biting Thomas's hand when he won't surrender the camera. He can't look away now. He just has to not act like his attention has been aroused.
Later, the woman corners him again, this time at his studio. He's attracted to her, as she has the physique of a model but not the attitude he's come to hate. He toys with her, gets her high. Then he takes a closer look at the pictures he's taken and sees clues that something sinister might have been going on. Someone might have been trying to commit a murder; someone might have been spared; someone else might already have died. Every time he enlarges the pictures to see more, he sees both more and less. Is that a blurry face peering out of the shrubs, or is it just part of a tree trunk? Is that a dead body on the ground, or a pile of foliage? Now he can't look away, but also can't do anything with what he does see.
Blow-Up seemed like a step sideways, and a constructive one, for director Michelangelo Antonioni. His previous movies (L'Avventura, Red Desert) revolved largely around the boredom and detachment of privileged folk in the modern world, material tagged with the half-joking label "Antoniennui". Blow-Up is livelier, but clearly the same man at work: he regards the energy and color of 1960s London with detachment, but not contempt. He also trusts our intelligence as a viewer, with both the little things and the big ones. When Thomas meets his publisher in a restaurant, there's no chatting-up that a lesser movie would use as handholding; they just go straight to business, and we can see for ourselves what the business is. And when Thomas squints at the blow-ups in his lab, Antonioni cross-cuts between them to let us connect the dots as he does. The images do the heavy lifting, as they should.
The final fourth or so of the film has Thomas going on a sort of mini-odyssey through London at night to try and make sense of everything he's seen. I don't think this sequence, and everything that follows, is meant to be taken absolutely literally. Even if only because certain elements stray outside the absolute, flat realism of the rest of the film. E.g., I am not convinced that a dead body (assuming it actually existed) could remain in a public park, even in an ostensibly secluded part of it, for the better part of a day and an evening. And the way the fans in the rock club react when a guitarist wrecks his instrument is like a bad parody of such behavior — or maybe a brutal distillation of it down to two essential reactions, boredom and monomania. Much like the rest of the movie.
Most people reading this are familiar, I hope, with another great film about a voyeur who witnesses a possible murder: Alfred Hitchcock's Rear Window. Blow-Up is not about the maybe-murder; the details of what happens are only designed to attract Thomas's attention long enough for him to feel helpless in their presence. It's more about the way we can drift through life looking but not really noticing, let alone seeing. All this time Thomas has spent peering through a viewfinder and arranging what's in front of the lens, and he seems as disaffected by his work as a bureaucrat. His neighbor and sort-of friend, a painter who specializes in pointillist abstractions — only in retrospect do we realize they resemble photo blow-ups — for all his cerebrality, has more genuine curiosity about his work.
If Thomas is a bad person, the movie seems to be saying, it's only because he's spent so much time doing what everyone else around him has been doing: looking without seeing, regarding without appreciating. He of all people should know better. His damnation is that by the time he summons the energy to be truly curious about what he's looking at, it has been taken away from him, turned into nothing but an afterimage. I thought of the opening lines from Talking Heads's song "Drugs": And all I see / Is little dots …