Through April 18 at the Haggerty Museum of Art, the main gallery hosts three distinct photography exhibitions. Presented separately, the three photographers’ series reveal that truth is subjective. While the camera, an extension of the artist’s eye, faithfully records what is immediately in front of it, each photographer mediates the reality in front of the lens to create three very distinct truths.

The nine black-and-white ethnographic photographs from Cameroon are part of “Al Sol,” a larger body of images taken by Stella Johnson on her travels to three locations around the world, including Mexico and Nicaragua. The story she tells here is one of quotidian life in a bucolic African village, its denizens engaged in domestic activities: children read, a boy milks a cow, a woman pours grain into a pot. In a purely documentary style, none of the subjects break the fourth wall to address the camera, and Johnson’s role is that of a detached observer. Drained of color, the beauty of her images is found in the details: rough-hewn edges of thatched roofs, fabrics suffused with repeating patterns, intricately plaited hair.

Barbara Morgan, best known as a photographer of modern dancers like Merce Cunningham and Martha Graham, is represented with a series of creative photomontages and double-exposures in “The Montages.” Morgan belies the static medium of still photography through her compositions. She is a choreographer of images, and her photomontages contain an inner motion. Four prints feature a silhouette of an octopus, its shadow hovering over a mass of tiny people. In one, the face of the octopus is a grinning portrait of the publishing magnate William Randolph Hearst.

In one of Morgan’s later pieces, “Wild Bee Honey Comb Sky-Scraper,” the inventive composition relies on purely formal considerations and contrasts. As the title suggests, Morgan plays with scale and adds a honeycomb to a city skyline. Photomontages have their roots in Dada and a kinship with Soviet filmmakers. Like Kuleshov’s editing experiments, they ripple space and time to inscribe the past on the present, or vice-versa, using Vertov’s notion of “kino-pravda,” or “film-truth,” to create an illusory reality, or a composite truth.

Johnson’s documentary photographs and Morgan’s photomontages are at opposite ends of a spectrum of photographic truth. Third photographer Lucinda Devlin’s arrestingly beautiful, haunting series “The Omega Suites” is somewhere in between. Using long exposures in the light that is available, Devlin crafts visually stunning, poetic images of the interiors of penitentiaries’ execution rooms. From behind the glass of a witness room, Devlin captures the iconic electric chair or a lethal injection bed. The lethal chambers, empty in Devlin’s photographs, are institutional, sterile and elegiac.

At first, Devlin’s images appear to be objective studies of empty spaces. Like Johnson, Devlin documents what is in front of her, but the subject is not found within the edges of each frame, rather what is absent. Some of the empty spaces echo the hotel room interiors of Stephen Shore, whose photographs appeared in the gallery a year before. Unlike lodging for weary travelers, these empty beds render permanent, irrevocable sentences. Rather than lead her viewer to a conclusion, Devlin merely presents a place, and allows the tension in “The Omega Suites”to exist in the contrast between their tranquil palette and the politically charged nature of her presence.