LIFE photographer Gjon Mili (who also directed the classic 1944 short film, Jammin’ the Blues) often hosted jam sessions at his photography studio in New York during the 1940s. These pictures testify to the talent on hand — both musical and photographic — and the pure fun that was had.

Born in Albania, raised in Romania, Mili emigrated to America to study electrical engineering at M.I.T. Inspired, in 1937, by M.I.T.’s Harold Edgerton development of the stroboscopic light, Mili went on to experiment with strobes, film speeds, unusual compositions and subjects — in short, he applied his prodigious technical prowess to finding new ways of seeing. Time, he realized, “could truly be made to stand still. Texture could be retained despite sudden violent movement.”