Tuesday night was the only full concert conducting appearance at this year’s festival by Oregon Bach Festival Artistic director designate Matthew Halls. It was a doozy. Entitled “A Night at the Opera”, it was a nearly seamless exploration of operatic masterpieces by the three birthday boys of the opera this year: Wagner, Verdi and Britten. With evocative images projected on the rear wall of the stage, the OBF orchestra and a stellar array of vocal soloists presented a succession of operatic gems to the assembled gala crowd.