Fink was born in New York City in 1930 and grew up on the West Side of Manhattan.^[3] He was raised an Orthodox Jew but as an adult he was non-observant.^[3] His father and older brother were physicians.^[2] Fink gained an undergraduate degree from Louisiana State University, then served in the army in the early 1950s.^[3] Later he gained a law degree from New York Law School.^[3]

Fink was self-taught in photography, using a 35 mm camera and a home-made darkroom in his small apartment on West 92nd street.^[1]

His first photographs date from 1954, of friends, holidays in Europe, and scenes in New York City.^[2] "His photographs of gay life begin with groups of gay men photographed in Greenwich Village in 1967" and he continued to focus on his own LGBT culture in New York City throughout the 1970s and 1980s.^[2] He photographed many of the annual Pride Marches beginning with the first in 1970—the Christopher Street Liberation Day march;^[4][5][6] the West Village's gay bar culture, especially on West Street;^[2][1][7][8] and in particular the abandoned West Side Hudson River piers, such as Christopher Street Pier. The rundown piers served as a space for gay men to interact and Fink photographed the cruising and sexual encounters, including his own.^[9][10] He made both candid photographs as well as those where his subjects knew they were being photographed.^[1][9] Elsewhere too, he often made self-portraits.^[7][9]

Fink neither published nor exhibited his photographs in his lifetime,^[1][9] sharing them only with close friends.^[3] At the time of his death he had over 5,000 prints^[11] and around 25,000 negatives.^[7]

Little is known about him.^[9][7] Most of his working life was spent as a lawyer for the New York City Transit Authority, where he investigated and defended the city against accident claims.^[2][3] "He lived frugally, spending much of his income on photographic supplies."^[2]

Fink was "well known in the gay scene of the West Village of the early 1980s"^[3] He "was a colorful and ubiquitous character in the Village and at Pride parades, usually appearing on rollerskates in short cut-offs, and a tight t-shirt with cameras always around his neck. He sometimes arrived on a bicycle or a motorcycle."^[2]

He died of complications relating to AIDS.^[2]

His complete photographic archive, consisting of work from 1954 to 1992, is held in the archive of the Lesbian, Gay, Bisexual & Transgender Community Center in New York City.^[7][2][9]

• Leonard Fink: Coming Out: Photographs of gay liberation and the New York waterfront. Biel/Bienne, Switzerland: Clandestin, 2014. Edited by Judith Luks and Thomas Schoenberger. ISBN 9783905297461. With a preface by Rich Wandel and an essay by Jonathan Weinberg ("Leonard Fink: making a scene") and by Schoenberger ("The sexualization of place—the piers between ruin and reoccupation"). Text in English and German. Published on the occasion of an exhibition at the Schwules Museum, Berlin.^[3]

• Leonard Fink Coming Out, Schwules Museum, Berlin, 2014/15^[12][3]
• Out for the Camera: the Self-Portraits of Leonard Fink, Leslie-Lohman Museum of Art, New York City, 2018. Work by Fink juxtaposed with work by Gail Thacker, Tee A. Corinne, Del LaGrace Volcano, Shari Diamond, Stanley Stellar and Frank Hallam.^{[7][8][13][14]} Included hundreds of images "from self-portraits in mirrors to gay bar culture" and Pride marches.^[5][7][8]

• Alvin Baltrop
• Diana Davies (photographer)
• Peter Hujar

• Pier Groups: Art and Sex Along the New York Waterfront. University Park, PA: Penn State University Press, 2019. By Jonathan Weinberg. ISBN 978-0-271-08217-2.

• Fink biography and photographs at Google Arts & Culture
• The artists who had sex and made art in New York City’s derelict piers at Dazed
• In the 1970s, Gay Sex Was Rampant on NYC Piers and in Trucks! Here’s the Story! at Hornet