[. . .] A bit of the mystery is resolved in “Men at Lunch,” a documentary about the photo that’s featured in the currentDOC NYC series at the IFC Center in Greenwich Village. Its director isn’t making any exorbitant claims. “We just muddied the waters a bit,” Sean O Cualain said with a smile during a recent interview in New York. “It was already a complex story full of unknowns. And we added a few more unknowns.”

But “Men at Lunch” does solve some of the puzzle created during a New York autumn when Babe Ruth’s Yankees were winning the World Series and Franklin Delano Roosevelt was winning the presidency. Produced by Mr. O Cualain’s brother, Eamonn, and made on a virtual shoestring, the film establishes the identity of at least two of the long-anonymous workers. Joseph Eckner, third from left, and Joe Curtis, third from right, were cross-referenced with other photos that the O Cualains were shown at Rockefeller Center. While the “Lunch” print itself bears no identifications, Eckner and Curtis were certainly the same men named on other photos taken that day. . .