Can anyone out there help me? I keep reading that I need a macro lens with a 1:1 magnification ratio if I want to scan negatives with a DSLR. I have a Canon 24-70 2.8L Macro lens with a magnification ratio of 1:3.45. Since the 4x5 negative is so much larger than a 35mm negative, why would I need a 1:1 dedicated macro lens? Since I can fill the frame with a focused 4x5 negative, what else could I hope for? Isn't my 24-70 macro more than enough to get great detail out of a whopping 4x5 negative?