This interview with Anton from British Journal Of Photography is such a great read.  Have included a couple of excerpts below including the Rob mention & you can read the interview in full by clicking on the above link.

From what I’ve read, Dennis Stock was an irascible guy. In the later stages of his life they called him ‘Dennis the Menace’ in the Magnum offices.

That’s true. Dennis Stock didn’t take any prisoners, he was no mercy, incredible. He had five ex-wives and a few of them didn’t want to talk to us about him – he didn’t leave them on good terms. We portrayed his relationship with his son at the end of the film as more positive than it was in real life.

Did Robert Pattinson have an interest in photography when you cast him as Dennis Stock?

I don’t think so. We made sure he got a camera months in advance to familiarise himself with that and to get a sense of wanting to take a picture of moments. Of course when you shoot with film you don’t take as many pictures. When I looked at the Magnum contact sheets, the Times Square sequence for example, there are are six shots. You’re much more focused.

You considered shooting the film in black and white but decided it might impinge on Stock’s photography?

I felt like we were not giving him enough credit. Of course there were other voices saying we should do black and white, because of financial reasons, but I’m happy that we didn’t do it.

A lot of photography writing talks about technique. Dennis Stock seemed capable of putting the hours in until James Dean finally relaxed and gave enough of himself so Stock could hold the camera and click the shutter. Do you agree with that?

Obviously a drive and hard work is something that can get you somewhere. Talent is not always the top priority that people associate success with. You have to spend time with someone if you want to take their photograph. I’m not sure if James Dean knew the quality of the pictures. I think Stock saw him and thought: “There’s a guy that wants to do something, he wants to do something outside the studio system.”