If interested, there are a bunch of long threads on camera scanners in the DIY forum. In fact those threads were the reason that the DIY forums were made. There's a whole thread on lenses. In short, use a lens optimized for the magnification you're scanning at. 1x is very different than 1/4x. The best value is an older macro (micro in Nikon terminology lens.) These fit on your camera without an adapter. They have fine focusing. The performance is pretty good. To get better, you have to get more complicated and expensive. For example, a 75mm Rodagon D is excellent at 1x. There's also a Rodagon optimized for 2x (or 1/2x). The highest resolving lens I tested was a Nikon 5x measuring microscope lens.....but the number of frames needed to cover even small film is excessive. In my own system, I found that going above 1x didn't help, even with 35mm techpan shot under controlled circumstances. Shooting a test target did show increases in resolution, but I don't make prints from resolution targets. Lenses also tested: Mitutoyo 2x APO, a whole bunch of enlarging lenses, both forward and reversed, Magnagons, Componon-Ms........