More people noticed this? Multiple times someone lifts a silver camera, takes a shot, and then lowers a black camera afterwards. Or the other way around, but you get the point... Sloppy, in a movie about photographers ;)
I'll have to watch again. Are you sure it's not how the light hits the camera? I'm pretty sure that the actors were each assigned cameras that they always used. I believe they even were allowed to keep them according to an interview with Taylor Kitsch.
“It’s not what a movie is about, it’s how it is about it.” RIP Roger Ebert
But maybe it only happens to Greg, because he buys a new camera, and therefore has two of them. A silver and a black one. Nikkormat, and a FM2 I think.
The best example is just around the 27th minute where Greg takes a picture of Kevin. There is no doubt there that it is not correct in this scene.