[7] His photographs were published on the inaugural cover of the literary magazine Evergreen Review and in the leftist journal Liberation.

Critics of the period referred to Feinstein as a master of his art, and his work was influential in the development of the New York school of photography.

There he was able to find and photograph a broad range of the human experience, from love to lust, joy to despair, comedy to drama.

Many of Feinstein's students went on to become fine art photographers of note; these included Mary Ellen Mark, Ken Heyman, Mariette Pathy Allen,[5] Wendy Watriss,[11] and Peter Angelo Simon.

[12] Additionally, Feinstein taught at the Annenberg School for Communication at the University of Pennsylvania, Philadelphia Museum School of Art, School of Visual Arts, the University of Massachusetts Amherst, Maryland Institute College of Art, Windham College, and College of the Holy Cross[13] After decades of working primarily in humanistic 35 mm film photography, Feinstein started in 2001 to create work digitally, using a scanner to photograph images of flowers, seashells, butterflies, foliage and botanicals.