While the photographer played by David Hemmings is never named in the film, his character is called "Thomas" in the screenplay.

The band that Thomas watches in concert briefly towards the end of the film is the real-life group The Yardbirds featuring a young Jimmy Page and Jeff Beck. The song they perform is "Stroll On."

Blow-Up was Michelangelo Antonioni's first entirely English-language film.

Actress, singer and fashion icon Jane Birkin plays the unnamed young blonde who engages in a Ménage à trois with Thomas and her girlfriend. Birkin was also famously the inspiration for the coveted Hermès Birkin bag.

The rabble-rousing costumed and made up young people at the beginning and end of the film are meant to be English students participating in a traditional ritual known as Rag Week, during which mobs of students dress up and take to the streets to raise money for charity.

Blow-Up did not premiere in Italy because of the national censors' disapproval of the film, mainly due to the scene with Thomas and the two young girls who visit his studio. The first screening held on the peninsula was in the independent Republic of San Marino.

In 1985 an interviewer asked Antonioni about the directing offers he received following the initial success of Blow-Up. "An American producer wanted me to shoot a fairy tale, Peter Pan," he said. "Can you see me doing Peter Pan? He called me into his office, and on the one side there was Mia Farrow, who was to take the lead role, on the other side was the composer and the artistic director (the music and scenery were all ready), and in front of me there was this producer with his checkbook out, offering one million and three hundred thousand dollars. And then I just asked: 'Since everything is ready, what do you need me for?' Those guys never understood why I turned them down. So many of my colleagues would have accepted. I have to say that sacrifices of a material kind have never really affected me much. The sacrifices that matter have to do with our view of life, they are of the moral kind. It's when you lie to yourself, when you compromise, that you really pay for it."

According to star David Hemmings, there was buzz that actor Terence Stamp had already been signed to play the lead role before he landed it himself. "Subsequently I learned that after Stamp had met Antonioni on the set of Modesty Blaise (1966)," said Hemmings in his autobiography, "the director had talked to him at some length about the picture...and even asked him for a list of his presumably 'swinging' friends. He offered Stamp's then lover, Jean Shrimpton, a role, but didn't show him the script or tell him much more. Terence was determined to work with the Maestro and, despite the vagueness and secrecy surrounding the project, put off a lot of other work to keep himself free for it when it eventually happened. He went and saw Antonioni in Rome a few times, but was so in awe of the great director that he didn't follow his instincts and others' advice to extract a contract or some kind of written commitment from him. Negotiations with MGM got under way and Stamp settled in to the task of learning how to behave like a photographer. Nevertheless, once Antonioni was in London making the final preparations for the movie, for some reason it seemed he changed his mind and no longer saw Terence in the role...Although he'd never had a contract, he still managed to get MGM to pay him some money to compensate him for all the other jobs he'd blanked in order to work with the Maestro. Astonishing as it may seem, I've never met Terence, although I fear he's never forgiven me for doing him out of Thomas in Blow-Up. But then, he did me out of Captain Troy in Far from the Madding Crowd (1967), so I guess we're quits."

According to David Hemmings, the scenes in the park were filmed "over a series of consecutive days in Maryon Park, Woolwich, an extraordinary and underused oasis of rus in urbe, just beyond Charlton Athletic's football ground."

In order to communicate with and understand Antonioni better, David Hemmings was inspired to learn the Italian language, which he started doing on the set of Blow-Up. "...as a result," he said in his autobiography, "Italian is now my second language and Rome is my favorite city."

According to David Hemmings, the famous party scene towards the end of the film was quite realistic. "To give as much verisimilitude as possible to this party scene," he said, "Antonioni had adopted the risky strategy of instructing that all the extras be given massive joints made with the best Lebanese hash. The air was thick with ganja smoke and the bit players were all lolling around, giggling inanely and doing nothing to help the concentration of the speaking parts."

Famous Quotes from BLOW-UP

"My private life is already in a mess. It would be a disaster if..."

"So what? Nothing like a little disaster for sorting things out."

--Jane (Vanessa Redgrave) and Thomas (David Hemmings)

"Don't let's spoil everything. We've only just met."

"No, we haven't met. You've never seen me."

--Thomas and Jane

"I thought you were supposed to be in Paris."

"I am in Paris."

--Thomas and Veruschka (Herself)

"Couldn't you just give us a couple of minutes?"

"Couple of minutes? I haven't even got a couple of minutes to have my appendix out." --The Blonde (Jane Birkin) and Thomas

"What did you see in that park?"

"Nothing."

--Ron (Peter Bowles) and Thomas

Compiled by Andrea Passafiume