A few days ago, I let my niece play with my SLR camera (Canon AE-1). It had no film in it and I made sure she didn't break anything. However, I failed to notice that she changed the ISO to 200. The next day I loaded my camera with 400 film. I've only taken about 4 shots with the ISO set at 200. Is there anyway I can change the film to 400 without ruining the film?