Theoretically, the area of film around the sprocket holes is completely unexposed, so it should be completely black on the print. When making contact prints, should I just adjust my time just until the sprocket holes become invisible? If the sprocket holes are still visible, is that bad? Is this a useful guide when doing enlargements as well? If I print a 135 frame onto 8x10, I have strips across the long dimension of the paper where I can see the sprocket holes. What can this tell me about my exposure onto the paper? Should the holes always be invisible?