By Alison Oldham POETIC, mysterious, transitional moments when the light is right are the trigger for Dorothy Bohm s personal photographs. Her daughter, art historian Monica Bohm-Duchen, says her mother never manipulates images but aims to capture a mome

By Alison Oldham

POETIC, mysterious, transitional moments when the light is right are the trigger for Dorothy Bohm's personal photographs.

Her daughter, art historian Monica Bohm-Duchen, says her mother never manipulates images but aims to "capture a moment that a millisecond later will be gone forever" - an urge driven by losing the world of her childhood at 14 when she fled Nazi-occupied Lithuania for Britain in 1939.

"The photograph fulfils my deep need to stop things from disappearing," Bohm wrote in a memoir in 1994. "It makes transience less painful and retains something of the special magic, which I have looked for and found. I have tried to create order out of chaos, to find stability in flux and beauty in the most unlikely places."

Few photographs in her exhibition Ambiguous Realities at St John's Wood's Ben Uri Gallery come closer to that goal than the one of trains in Liverpool Street Station taken in 1988. The eye is drawn into the depths of the composition by the ever narrowing gap between brightly painted coaches, then upwards into the vaulted roof spaces of the Victorian station.

In her photograph Schoolboys & Teacher, Metro Station, Paris 1994, we are shown a group of schoolboys interacting and people who are more introspective - a pensive child, bare-chested young man in a poster and an elderly passer-by. In the fine catalogue essay, Bohm-Duchen interprets this photograph as "a witty and poignant distillation of the Three Ages of Man", with the female teacher occupying, as women often do in the photographs, an uncomfortable position.

She separates her mother's images into three often overlapping groups. In the first are close-ups of torn posters, graffiti and other urban ephemera, many with disconcerting eyes facing outwards.

In the second are facades of often dilapidated buildings and murals that require a double take to determine what's real and what not, like the giant boot on a shop near Camden Lock.

The third group is less urban and more lyrical - including a photograph of a potter's workshop, where the shapes of vessels, whitewashed walls and sunlight suggest a foreign location. It was actually taken near St Ives and the exoticism perhaps derives from the potter, Jason Wason, having formerly worked with master ceramicist and Orientalist Bernard Leach.

Bohm set up a commercial portrait studio in Manchester in 1945 at the age of 21. By the 1970s, she had won international recognition for her innovative black and white "street" photography.

She belongs to the generation of Humanist photographers that includes Henri Cartier-Bresson and André Kertész, both of whom she knew and admired.

And she has lived in and photographed Hampstead for 50 years. The book Hampstead - London's Hill Town, with more than 130 of these pictures and text by local bookseller Ian Norrie, was published in 1981 - the year she had a retrospective exhibition at Camden Arts Centre.

The possibilities of colour photography began to intrigue her after visiting Kertész in New York in 1980 and seeing his Polaroids.

Colour film enabled her to work in rain and half-light and to respond to different stimuli. "My eye is alerted to bursts of colour where unexpected things emerge."

Newspaper Stand In The Rain, Lisbon 1996, shows what she means, with its bright children's windmills and an opaque sheet of plastic blurring a figure behind.

This enthralling exhibition reveals Bohm's idiosyncratic response to many lands and cultures - grandiose gates above a misty Lake Lugano, a high-angled shot of a road junction in Massachusetts, vignettes of street life in Tokyo and Marrakech. Images linger in the mind's eye.

"Sometimes I want a picture to ask why, and not to be too easily deciphered and decoded, because our lives are like that," she says.

Ambiguous Realities, Colour Photographs by Dorothy Bohm runs until February 25 at the gallery at 108a Boundary Road. Entry is £3 (£2 concessions, free to Friends, NACF members and children).