Cillian Murphy has said that he studied every small detail about J. Robert Oppenheimer in his portrayal of the father of the atomic bomb last summer.In a Q&A on Friday at the Santa Barbra International Film Festival, the actor spoke to festival director Robert Durling about his characterisation in Christopher Nolan’s Oppenheimer, saying he wanted to focus in particular on the small details of his character – especially with the film being shown on IMAX.Durling said he noted the cigarette stains on Murphy’s fingers during one scene, something that delighted Murphy.He explained (via Movie Maker): “I’m so glad you noticed that! Our amazing makeup artist Luisa Abel — we did that every single day and I would get really into the detail.