Actually, I found a very inexpensive solution a few years ago. I had around 10 thousand slides from my late father's collection that had been hanging around for almost 50 years and had to digitize them before they degraded. I used an Opteka slide copier tht I purchased on Amazon for around $50. This product worked great. I have a dedicated slide scanner (Minolta DiMage Scan Dual 4). The Minolta works great but would have taken ages since I have a so many images to scan. I used the Opteka with a 50mm 1.8 prime lens. The filter thread size on this lens is 52mm like the Opteka. At f9 it works great. It works best with daylight, but do not point it directly towards a bright sun because the image will look very grainy. Possibly due to the matte translucent backing on the unit. The image fills about 70% of the screen with a DX sensor. I ordered a 62-52mm stepdown ring to use it with my 60mm 2.8 Nikor Macro, it did a better job of filling the screen and the picture quality was a little sharper. I'm pretty happy with the speed that I was able to do this and the color is great. NEF should give you even more control of the results. If you have a spare DSLR that you don't mind putting those extra thousands of clicks on, this is a great way to go. I completed this task in a very short time.
D700, D300, D70, SB-900, SB-910, Nikkor 24-70 2.8, Nikon 70-200mm f/2.8G ED VR II AF-S, Nikkor 50mm f/1.8G AF, Nikkor 60mm f/2.8D AF, Nikkor 85mm f/1.8G AF-S, Nikkor 70-300mm f/4-5.6G AF, Nikkor 18-35mm f/3.5-4.5D IF-ED AF, Rokinon 8mm Fisheye