The work of the New York photographer Helen Levitt, who has died aged 95, is at once unique and typical, born of the flowering of "documentary expressionism" in 1930s America. She combined a passion for in-depth recording of the lives of migrant workers and city slum-dwellers with an artistry - and a particular delight in children - all her own.
It is no coincidence that the writer and film critic James Agee, who - together with Walker Evans - created a milestone in the classic portrait of the American poor, Let Us Now Praise Famous Men, also provided the text for Levitt's seminal 1965 book A Way of Seeing: Photographs of New York. Photobooks which followed include In the Street: Chalk Drawings and Messages, New York City, 1938-48 (1987) and Mexico City (1997). The publication dates, generally some 40 years after the images were taken, suggest the extent of the time-lag between the creative act and its wide recognition.
Levitt was born in Brooklyn, New York, where her Russian-Jewish father ran a wholesale knitwear business. Rather than complete high school, she learned developing and printing in the studio of a commercial portrait photographer. From the beginning of her career, Levitt's work attracted considerable critical attention. She started studying with Evans in 1938, aged 19, and was early on compared with Dorothea Lange and other documentary photographers employed by the Farm Security Administration during the Great Depression.
Yet she was keen to develop her own style and techniques. As soon as she saw an exhibition of Henri Cartier-Bresson's work at the Julien Levy gallery in New York, she decided to move on from the large-view cameras then in favour to Cartier-Bresson's 35mm Leica, with its right-angle sights. (At times, she even resorted to using a prism lens to disguise her focus to her subjects.)
She also favoured working in the midst of city life. Levitt greatly preferred using available light and loved movement; she would harness water, windows, even - memorably, in a group shot of girls blowing soap - bubbles, to serve as prisms refracting both. And she developed the particular skill of using a friendly and unobtrusive manner to persuade children to ignore her or show off. Images of them beating the heat under a spouting street-corner water hydrant, or lined up in outsized masks to go trick-or-treating for Halloween are black-and-white period classics of apparently natural and playful pleasures.
In July 1939, the new photography section of the Museum of Modern Art (Moma) included Levitt's work in its inaugural exhibition and, in 1943, she obtained her first one-woman show there. Yet she had to wait for the 1960s and later for four major shows (two solo, two group), partly on the wave of feminist rediscovery of women's creative achievements. In the 1980s came Sixty Prints by Six Woman Photographers, which again included Lange, as well as Margaret Bourke-White, Tana Hoban, Hazel Larsen and Esther Bubley.
The show toured Europe first in 1982, showing at the Ikona gallery in Venice and (as part of a Photo-Portrait group exhibition) at the Rheinisches Landesmuseum in Bonn, then in 1985 at the Fotografiska gallery in Stockholm. Edited collections of Levitt's work were shown in New York at the Sidney Janis gallery in 1980 and at the Laurence Miller gallery in 1987. In 1991, a first national retrospective was given by the San Francisco Museum of Modern Art.
Yet, despite initial success, the early years were never easy. For much of the 1950s, Levitt worked operating a cine camera and as a film editor. Encouraged by Agee and the painter Janice Loeb (who was for a time married to Levitt's brother Bill), she worked with the least fussy 16mm equipment she could find, which allowed her to hold the camera at waist-height and film on the streets virtually unnoticed.
Her work with Agee and Loeb on the documentary film The Quiet One in 1948 saw her nominated for an Oscar as writer, together with Loeb and Sidney Meyers. The collaboration continued with a short film on New York's Spanish Harlem, In the Street. In 1964 Levitt received a Ford Foundation grant to continue in documentaries, extending, as the photographic historian Naomi Rosenblum put it, "the same fusion of artless innocence and sophisticated vision that had informed the earlier still photographs". Levitt was still only the second woman photographer to obtain a photography fellowship, 18 years after her mentor, Lange. She received prestigious Guggenheim Foundation awards in 1959 and 1960.
In 1959 Levitt began to work in colour, her eye informed both by natural contrasts and unexpected affinities. Given the variability of colour-film processing, she was brave to persist and establish herself as - in the words of Peter Galassi, senior photography curator at Moma - "a pioneer".
From the start, she contributed regularly to Harper's Bazaar, Time and Fortune, the major colour magazines of their day, as well as the New York Post. She had gone beyond the iconography of street photography and no longer focused predominantly on people as her subjects.
Images that spring to mind include two speckled hens marching past two red-and-white speckled chairs on the pavement outside a furnishing store; or the brilliant pinks and greens of a street chariot selling "snowballs" - ice shavings topped with vividly highlighted syrups - surreally situated in front of a tilting phone box and with a disembodied hand extending a luminous ice-cone into the frame of the picture. Unexpected angles, when objects move in and out of the field of vision, are far more characteristic of her work than an enclosed view.
In later years, Levitt, always fiercely defensive of her private life, refrained from attending launches of her work or giving interviews about it - although she did emerge to speak to the New York Times in 2002, and seemed as curious as ever about the world outside. She believed in letting the work speak for itself, which seemed to inspire writers to poetic heights in describing it.
The photographer and curator Van Deren Coke saw her films as filled with "the strange and often poignant spontaneous occurences that take place along New York's crowded streets", while Cecil Beaton referred to "a body of work that demonstrated her uncanny ability to merge strong empathy for her subjects with a sense of moment and formal order".
But perhaps it should be left to her long-term collaborator, Agee, to sum up the work as "the record of an ancient, primitive, transient and immortal civilisation, incomparably superior to our own", and its creator as "one of a handful who have to be described as good artists, not loosely, or arrogantly, or promotively, but simply because no other description will do".
Levitt is survived by her brother.