Article Photos: Elton John and Leon Russell: Documentary on their collaboration on “The Union” airs Thursday on HBO 1/1

 The Tribeca Film Festival opens tonight with the world premiere of director Cameron Croweís "The Union." The documentary chronicles the efforts of British pop star Elton John, left, to reconnect with and revive the career of Oklahoma music icon Leon Russell, right, Johnís idol in the early days of his career. PHOTO PROVIDED     ORG XMIT: 1104191602393060