The literary form closest to photography is the Japanese haiku. The rigid 17-syllable haiku format corresponds to the set rectangular frame of the picture; each art consists of the significant juxtaposition of concrete elements, verbal or graphic, and each illustrates a fixed moment in time. By contrast,”The Brown Sisters,” Nicholas Nixon’s series of 31 8-inch-by-10-inch black-and-white pictures currently on view at the Yossi Milo Gallery, aspires to be the photographic equivalent of a novel: It deals with the development of several characters interacting over an extended period.

In 1975, Mr. Nixon took a picture in Hartford, Conn., of his wife and her three sisters. The next year he took another, and it was agreed at that time that every year the women would gather to have one picture taken, always with the same lineup – Heather, Mimi (the youngest), Bebe (the oldest and Mr. Nixon’s wife), and Laurie – and always with them “physically and psychologically present.” Over the years, pictures were taken in 18 different locations in Massachusetts, and in East Greenwich, R.I.; Cincinnati, Ohio; Woodstock, Vt.; and Grantham, N.H.The four are always close together, and since the camera is close to them, only a little background is seen – the shore of a lake, a slice of ocean beach, a few trees, some low hills. The New England locations seem right: The women have handsome Yankee faces – sturdy, intelligent, disciplined – and they have aged gracefully, as things in New England tend to. They are, of course, 30 years older now than when they started.

As with Louisa May Alcott’s “Little Women” series of novels, Mr. Nixon’s fans look forward each year to the next picture of the Brown sisters, wanting to see how the girls are doing. Some years the sisters have their arms affectionately around each other, some years one or another will have her arms folded in front of her (Laurie does this a lot). They don’t wear makeup, but their faces transform and their hair changes.Their clothes are always casual – a bit arty, a bit L.L. Beanish – but the shapes inside the clothes change. Sometimes, for whatever reason, one of the women will be looking away from the camera.

The pictures at Milo are arrayed three deep in chronological order; the viewer starts at the left and reads to the right trying to impose a narrative that accounts for whatever differences show from year to year.You get to know these women the way you know people you have seen around the neighborhood over a long period of time: You feel a relationship to them without really knowing anything much about them.

“The Brown Sisters” is simple in its format, straightforward in its execution, and novelistic in its effects. It is about family, and it is about four individuals; it is about women, but you know there must be men involved, and, given the times, complex relationships. It is about what time does to the sisters, and about their courage in showing up again and again to confront the camera. Seeing the 2005 portrait, you anticipate 2006.

There are selections in “Life and Times” from several other series Mr. Nixon has worked on. “Family Pictures” is about his wife and their growing children. As with “The Brown Sisters,” the use of a large-format view camera transforms what might otherwise be mere snapshots into lovingly detailed investigations of the quotidian, especially in Mr. Nixon’s radical close-ups.”Clementine and Bebe, Cambridge” (1986) is an affectionate examination of baby drool. In “Sam and Clementine, Cambridge” (1986), both children are seen from about waist level, but Clementine is standing on her hands and so is visible from the waist up. Sam is seen from the waist down: His scraped knees, scratched leg, and the delicate blond hairs on his calves amount to a portrait.

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Harry Callahan (1912-99) is a seminal photographer whose work Nicholas Nixon must have studied. Among their similarities is a respect for the formal properties of photographs, an instinctive humanism, and the many pictures each took of his wife.

Callahan was a particularly protean photographer, a man willing to take chances who mastered several styles and camera formats. An exhibition at Danziger Projects of his “Women Lost in Thought,” a series he worked on in 1950, makes clear that he was influenced by the photographs Walker Evans took surreptitiously on New York subways a decade earlier.

Evans’s pictures of introspective Depression-era riders, which were exhibited recently at the Metropolitan Museum of Art, are in many ways more revealing than ones in which the subject acknowledges the presence of the camera. Callahan took his pictures on the sidewalks of Chicago, and like Evans underground, he faced formidable technical challenges. Because the faces of the women Callahan photographed completely fill the picture frame, there is no sense of place; the extremely long developing time his exposures required reduce the tonal scale to harsh blacks and whites, giving many of the faces an expressionistic cast. The resulting portraits have enormous presence.

The pictures are all untitled, so it is difficult to refer to individual ones, but it is interesting that they are so redolent of a particular time, even though the information they contain is minimal. The women’s lipstick, eyebrows, jewelry, and hairstyles set them in mid-century, as do their expressions of deep concern. They are mostly middle class or working class and the economy was good then, so why do they appear to be so burdened? Each seems occupied with some deep puzzle as she passes by on the thoroughfare, concerned not with just personal dilemmas but with vast existential conundrums.

Nixon until January 21 (525 W. 25th Street, between Tenth and Eleventh Avenues, 212-414-0370). Callahan until January 14 (521 W. 26th Street, between Tenth and Eleventh Avenues, 212-629-6778).