Some photo shows are about fine art; some are about technique; some are about their photos’ subject or a purpose that transcends the medium; and some are about the photographer. If " There Is No Eye, " the collection of 120 photographs (displayed with personal text) by artist/musician/folklorist/filmmaker John Cohen at BU’s Photographic Resource Center, can be classified at all, it falls somewhere between the latter two options. Cohen has crowded the PRC’s walls with disparate sets of casual documentary photographs covering Appalachian musicians, Beat Generation luminaries, rural Peruvians, Greenwich Village urban folkies, and gospel churches.

There is no single subject — except a chronicle of the projects and passions that have defined Cohen’s life. And it’s obvious that each project existed outside the traditional sphere of documentary photography — he wasn’t taking pictures to create a definitive record or even make a powerful statement. These are photographs he took along the way as he immersed himself in traditional American music, Peruvian culture and weaving, and the loft life in 1950s New York. And because the show’s about so much more than photography, it speaks to a wide audience. The PRC reports that this is a record-breaking blockbuster exhibit — drawing niche crowds with interests as diverse as the show’s topics.

But to say there is no single subject to " There Is No Eye " is not to suggest there isn’t a unifying purpose. Cohen — a Yale-trained painter who studied under Josef Albers and later insinuated himself into the nascent Abstract Expressionist scene in New York, and who founded the pioneering roots-revival group the New Lost City Ramblers — has focused his life on creativity (and creative movements) existing outside or on the fringes of commercialism. That the Beat poets half a century later outsell themselves in their salad days or that decades of popular music can be traced back to the way that rural folk traditions were aimed toward the mainstream by Alan Lomax, the Seegers, Woody Guthrie, Bob Dylan, et al. only proves his knack for being drawn to the right place at the right time.

Cohen hung with culturally influential, if sometimes unheralded, crowds — as an observer and as a participant. His New Lost City Ramblers ( " Uncle John’s Band " of Grateful Dead fame) re-created the authentic Americana of the ’20s and ’30s. He’s made 15 documentary films, two of which — 1963’s The High Lonesome Sound, covering the life and music of Kentucky’s rural poor, and 1970’s The End of an Old Song, exploring the ballad tradition in the mountains of North Carolina — will be shown in Morse Auditorium, upstairs from the PRC, this Monday. He worked with photographer/filmmaker Robert Frank on the experimental 1959 film Pull My Daisy, which is narrated by Jack Kerouac and stars Allen Ginsberg, Gregory Corso, and Peter Orlovsky. He photographed Dylan, fresh in from Minnesota, on a Third Avenue rooftop in 1962. He was friends with Reverend Gary Davis. He attended the original dada-esque happenings staged by the Red Grooms/Claes Oldenburg crew.

In terms of the mid-century off-culture elite, John Cohen, now 71, was well connected. And he photographed his associates from the inside. That insider’s perspective — bespoken by both the offhand scenes he recorded and his available-light grab-shot/snapshot/Robert Frank–influenced technique — is what makes " There Is No Eye " different from a collection of standard documentary essays — and something of a disappointment to those who turn up at the PRC expecting polished photographic studies. The show’s an autobiographical retrospective from an influential but low-profile celebrity who was a part of big things. Viewers, many of whom wouldn’t have known John Cohen by name, envy his involvement. This is exciting stuff.

THE EXHIBIT’S TITLE is appropriated from a line from Dylan’s free-wheeling liner notes to 1965’s Highway 61 Revisited: " You are right John Cohen — quazimodo was right — mozart was right . . . I cannot say the word eye anymore . . . when I speak this word eye, it is as if I am speaking of somebody’s eye that I faintly remember . . . there is no eye — there is only a series of mouths — long live the mouths — your rooftop — if you don’t already know — has been demolished . . .  "

The rooftop reference harks to the location where Cohen first photographed Dylan. The " no eye/long live the mouths " conceit is likely some other insider/personal reference or, perhaps, off-the-wall metaphorical inspiration. In the introduction to the exhibit’s companion volume (powerHouse Books, 200 pages, $45), Greil Marcus interprets the Dylan text to support Cohen’s belief that " the picture exists outside the photographer’s intention. " Marcus’s own observations are excellent, but the Dylan-quote connection is a stretch. I suspect that Cohen is less concerned with the integrity or the limitations of the photographic arts than he is with the idea that any medium is an inadequate means of interpreting real things — lives, music, relationships, the creation of art. Still, he offers us these photographs.

In truth, nothing so esoteric as the issue of the medium-imposed distance between the photographer and his subjects — or between the viewer and his subjects — is likely to dog your tour of Cohen’s exhibit. You’ll be having too much fun spotting Dylan as a youthful naïf at New York’s Gaslight club, or chuckling at Red Grooms wheeling a painting across Third Avenue in what looks like a converted baby carriage, or marveling at the uncharacteristic expression on Kerouac’s face as he stains to listen to himself on the radio, or being drawn into the family clusters of Kentucky musicians making down-home music down home, or wondering how much fun it really was to rub elbows with Kerouac and Ginsberg over Chinese food. There’s a lot of cultural nostalgia in this show; there are a lot of " there at the creation " moments. And you shouldn’t hesitate to revel in them.

The High Lonesome Sound and The End of an Old Song screen in Morse Auditorium at 7:30 p.m. this Monday, February 25; there’ll also be an unplugged performance by Cohen and the Dixie Butterhounds. Admission is $15, and reservations are suggested; call (617) 353-1662.