John Lennon pulled no punches about how much he detested the Beatles' 1964 knockout photo shoot with Muhammad Ali ... that's according to the guy who snapped those iconic images.
Famed Beatles photog Harry Benson spilled the tea on the tension between the legends while celebrating 60 years of snapping pics of the band, telling Fox News Digital ... Ali wasted no time throwing shade, telling the singers their music wasn't all that.