Soho Photo, a cooperative gallery dedicated to the art of photography, hasn’t been in Soho for more than half a century. The venue got up-and-running in 1971, squared away in a loft at the intersection of Prince Street and West Broadway. This was back when the area south of Houston Street was populated by — no, not high-end hotels, luxury boutiques, and scads of tourists but struggling artists, scrappy galleries, and bars offering bottomless libations that didn’t cost an arm-and-a-leg.