Hm... shouldn`t turning the film around produce problems with sharpness, resp. focusing? If the emulsion side is on the pressure plate now, it is further away from the camera lens so plane of sharpness on the negative should move into close-up range. You focus on 30ft, but sharpness is on 25ft for example.

. At least the RED stuff is actually different, even if it's just wound backwards. 

