The young swimmer in Telemachus tells Mulligan that their mutual friend Alec Bannon has written him a postcard which mentions that he has met a “Photo girl” in Westmeath, and Mulligan takes the young woman's employment as an occasion for ribald joking: “Snapshot, eh? Brief exposure.” It will turn out that the girl is Bloom's daughter Milly, and that she merely works in a photographer's shop. But there were multiple reasons at the turn of the century to associate the relatively new art of photography with sexually alluring young women.
Throughout the novel, the absent person of the fifteen-year-old Milly Bloom is charged with sexual interest and anxiety. Her pubescent blooming has caused considerable tension within the Bloom household, and the letter that her father receives from her in Calypso, which mentions Bannon, fills him with worry that she may become sexually active. The young men of the novel certainly view her in that light. In Oxen of the Sun, in another gathering of raucous twenty-somethings that includes Bannon and Mulligan, we hear her referred to as a "Bold bad girl from the town of Mullingar."
In an essay titled "Joyce, Early Cinema and the Erotics of Everyday Life," published in Roll Away the Reel World: James Joyce and Cinema, ed. John McCourt (Cork University Press, 2010), Katherine Mullin provides a contemporary context for the young men's assumption that a "photo girl" might be a girl of easy virtue: "This easy innuendo attests to the equivocal nature of Milly's voguish career. 'Photo girls' were often employed as lab assistants and colourists, but as attractive young women fronting photography booths and studios, they were also hired to drum up trade, especially in tourist resorts like Mullingar" (51-52).
Mullin adds that the erotic reputation of these "photo girls" was enhanced by the advertising posters featuring Kodak Girls that were common in the United Kingdom in the early 20th century: "They were quickly established as fin de siècle sex symbols, a status crystallised in the Eastman Kodak advertisements launched in 1893 and enduring into the mid-1920s. 'Kodak Girls', who brandished cameras in their distinctive blue and white striped costumes and daringly shortened skirts, were flirtatious, adventurous and spirited heroines of modern life, and Milly shares both their youthful sexuality and their promotional function. Milly's awareness of her ambiguous role is implied in her letter, which moves from her claim to be 'getting on swimming in the photo business now' to an allusion to Blazes [sic] Boylan's 'song about those seaside girls'" (52). The song is about well-dressed, erotically captivating women at the seashore—and some of the Kodak posters, like the one reproduced here, in fact showed their girls on the beach.
In addition to these soft uses of sex to sell photographic products and services, there was a burgeoning pornography industry. Almost from its inception, the art of photography had been turned to prurient uses. In later Victorian times and the Edwardian decade (1901-10), the market was flooded with naughty picture postcards, ranging from titillating shots of scantily clad young women to graphic depictions of intercourse. Bloom knows these lewd postcards well. In Circe, the honorable Mrs. Mervyn Talboys accuses him of having "sent me in double envelopes an obscene photograph, such as are sold after dark on Paris boulevards, insulting to any lady. I have it still. It represents a partially nude señorita, frail and lovely (his wife, as he solemnly assured me, taken by him from nature), practising illicit intercourse with a muscular torero, evidently a blackguard. He urged me to do likewise."The "nude señorita" comes from Bloom's knowledge of what resides in his desk drawer: a photograph of a young Spanish woman performing fellatio on a bullfighter. Ithaca reveals that he owns "2 erotic postcards showing a) buccal coition between nude senorita (rere presentation, superior position) and nude torero (fore presentation, inferior position) b) anal violation by male religious (fully clothed, eyes abject) of female religious (partly clothed, eyes direct), purchased by post from Box 32, P.O., Charing Cross, London, W.C." The photograph of a monk having anal intercourse with a nun comes up again in Penelope, when Molly imagines a sister coming to the house to take care of a sick Bloom: "like the smutty photo he has shes as much a nun as Im not."
The references to Paris and London in connection with erotic
photos indicate that the pornography industry has yet not made
its way to puritanical Ireland. As Stephen says in Scylla
and Charybdis, “Elizabethan London lay as far from
Stratford as corrupt Paris lies from virgin Dublin.” But
Dublin men are certainly making their way to it.
 Ulysses also explores the erotic potential
of the mutoscope, a device
that enabled individual users to view an early form of motion
pictures. In Circe this device supplies the
inspiration for Bloom to gaze through a keyhole at his wife
having intercourse with Blazes Boylan.