I got my sheets of 4x5 film back and every 4 sheets shows light leak on them. I realized I may have done that when I first opened the box and put them in the holders while in the changing bag. Dont ask me how. If light got in while the box was open, what are the chances the whole box is fogged? Or if not, how many sheets down should I go before the remaining amount will be okay? I figured a stack of sheets on top of each other might help protect the ones below? What are my chances I still have some good sheets? Its a box of 50 and only 10 or less sheets have been used.