Keaton plays "Buster," a humble tintype photographer ("they make excellent ash-trays!"), scraping together a meager living photographing interested passers-by on the streets of New York. While photographing an attractive woman (Marceline Day), the two are besieged by a crowd of people—a big event is happening on the street and they are crushed by innumerable rubber-neckers trying to get a glimpse of what's going on. This includes a newsreel photographer from M-G-M (meta reinforcement), who the woman, Sally, pays a lot of attention to.
Through the eyes of love, Buster sees the future and it is not seen in tintypes. After being rejected by M-G-M Newsreels (whether Sally is the receptionist, hence her interest), he takes his savings from his old technology (tellingly nearly destroying his apartment in the meantime) to buy a newfangled cranking movie camera and prove his worth.
Sally, however, takes pity on the hapless schnook and agrees to go out with him when her Sunday date falls through. The sequence begins with an elaborate crane shot that moves up and down the stairwell of Keaton's apartment house as he tries to get time on a shared phone in order to talk to Sally. When she agrees to see him, he's so excited that he runs to her boarding-house arriving there before she can hang up the phone.
The date is a battle of logistics: it seems all of New York is in cahoots to separate Buster from Sally and he must come up with unique and frequently dangerous ways for them to be together. This violation of space is a running gag throughout the date, where folks just impose their will on Buster, and he must come up with ways to regain it, change it, or accommodate it. The most bizarre of these is when he must share his cramped changing room at a public pool with a man (Edward Brophy, the film's unit manager) who insists on occupying the same room—the confusion of clothes and limbs (in one extended take, it should be noted) is hilarious, confused and unorganized in an unchoreographed awkward tangle.
The date (such as it is) does not go very well, with the intervention of Buster's news-reeling rival (Harold Goodwin) for Sally's affections driving her home with in a torrential down-pour with Buster exposed to the elements in the car's rumble-seat.
But, once again, she takes pity on him and gives him a choice assignment when rumors of a skirmish at a Chinatown celebration reaches her desk. She gives Buster the assignment, and he barely survives being shot, run-over, and arrested while recording the event. Although the footage is spectacular, Buster has nothing to show for it, but a three foot roll of film. He evidently forgot to load the camera.
Well, that's how it appears, anyway. In the midst of the film, Buster somehow manages to acquire a hurdy-gurdy monkey who has more than a monkey's paw in having Buster come away with the plum assignment empty-handed. It should be noted that the on-screen chemistry between Keaton and the monkey is amazing, rivaling the affection between Keaton's character and Sally. Perhaps, the primate found in Keaton a fellow-acrobat and relentless performer.
In one of their attempts to inject formula into Keaton's film, the "real" M-G-M brass insisted that a shot of Keaton smiling be part of the end, but preview audiences expressed a dislike for it and it was taken out. It presaged the studio's forthcoming ideas on how to "improve" Keaton's likability to audiences, forcing him to do "talkies" and even sing when they moved into sound pictures. The Cameraman, with its story of a photographer forced to change, uncomfortably, with the times, is a bit of a reflection of Keaton's uneasy relationship with the studio, which would rapidly deteriorate.
It was added to the National Film Registry in 2005 for being "culturally, historically, or aesthetically significant." Keaton remembered his move to M-G-M as "the worst mistake of my career."