mdarnton
Well-known
Assuming that your negative stage or carrier is flat and parallel with the neg, the easy way to line things up is put a small mirror there, then adjust the camera so that the image of the reflected lens is in the center. Perfect, quick, and foolproof. As careful as I am, this trick improved my corner resolution and consistency over levels or lining up parallel lines by eye. If you're saying the corners of your lens are bad, that could simply be an alignment problem.